This commit will switch blender to use tangent space generated within

the two files mikktspace.h and mikktspace.c. These are standalone files
which can be redistributed into any other application and regenerate the
same tangent spaces. The implementation is independent of the ordering
of faces and the vertex ordering of faces.

8 files changed, 2249 insertions, 74 deletions

diff --git a/source/blender/blenkernel/BKE_DerivedMesh.h b/source/blender/blenkernel/BKE_DerivedMesh.h
index 79e9b11d4db..1f56c164fcc 100644
--- a/source/blender/blenkernel/BKE_DerivedMesh.h
+++ b/source/blender/blenkernel/BKE_DerivedMesh.h
@@ -533,7 +533,7 @@ typedef struct DMVertexAttribs {
 	} mcol[MAX_MCOL];
 
 	struct {
-		float (*array)[3];
+		float (*array)[4];
 		int emOffset, glIndex;
 	} tang;
 
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 5f5b413ecd8..ae724234459 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -106,6 +106,7 @@ set(SRC
 	intern/mball.c
 	intern/mesh.c
 	intern/mesh_validate.c
+	intern/mikktspace.c
 	intern/modifier.c
 	intern/multires.c
 	intern/nla.c
@@ -222,6 +223,7 @@ set(SRC
 	BKE_writeffmpeg.h
 	BKE_writeframeserver.h
 	depsgraph_private.h
+	mikktspace.h
 	intern/CCGSubSurf.h
 	intern/bmesh_private.h
 	nla_private.h
diff --git a/source/blender/blenkernel/intern/DerivedMesh.c b/source/blender/blenkernel/intern/DerivedMesh.c
index eedc2636991..79e23b77306 100644
--- a/source/blender/blenkernel/intern/DerivedMesh.c
+++ b/source/blender/blenkernel/intern/DerivedMesh.c
@@ -948,7 +948,7 @@ static void emDM_drawMappedFacesGLSL(DerivedMesh *dm,
 	}																			\
 	if(attribs.tottang) {														\
 		float *tang = attribs.tang.array[i*4 + vert];							\
-		glVertexAttrib3fvARB(attribs.tang.glIndex, tang);						\
+		glVertexAttrib4fvARB(attribs.tang.glIndex, tang);						\
 	}																			\
 }
 
@@ -2481,6 +2481,111 @@ float *mesh_get_mapped_verts_nors(Scene *scene, Object *ob)
 
 /* ******************* GLSL ******************** */
 
+typedef struct
+{
+	float * precomputedFaceNormals;
+	MTFace * mtface;	// texture coordinates
+	MFace * mface;		// indices
+	MVert * mvert;		// vertices & normals
+	float (*orco)[3];
+	float (*tangent)[4];	// destination
+	int numFaces;
+
+} SGLSLMeshToTangent;
+
+// interface
+#include "mikktspace.h"
+
+static int GetNumFaces(const SMikkTSpaceContext * pContext)
+{
+	SGLSLMeshToTangent * pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+	return pMesh->numFaces;
+}
+
+static int GetNumVertsOfFace(const SMikkTSpaceContext * pContext, const int face_num)
+{
+	SGLSLMeshToTangent * pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+	return pMesh->mface[face_num].v4!=0 ? 4 : 3;
+}
+
+static void GetPosition(const SMikkTSpaceContext * pContext, float fPos[], const int face_num, const int vert_index)
+{
+	//assert(vert_index>=0 && vert_index<4);
+	SGLSLMeshToTangent * pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+	unsigned int indices[] = {	pMesh->mface[face_num].v1, pMesh->mface[face_num].v2,
+								pMesh->mface[face_num].v3, pMesh->mface[face_num].v4 };
+	VECCOPY(fPos, pMesh->mvert[indices[vert_index]].co);
+}
+
+static void GetTextureCoordinate(const SMikkTSpaceContext * pContext, float fUV[], const int face_num, const int vert_index)
+{
+	//assert(vert_index>=0 && vert_index<4);
+	SGLSLMeshToTangent * pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+
+	if(pMesh->mtface!=NULL)
+	{
+		float * uv = pMesh->mtface[face_num].uv[vert_index];
+		fUV[0]=uv[0]; fUV[1]=uv[1];
+	}
+	else
+	{
+		unsigned int indices[] = {	pMesh->mface[face_num].v1, pMesh->mface[face_num].v2,
+									pMesh->mface[face_num].v3, pMesh->mface[face_num].v4 };
+
+		map_to_sphere( &fUV[0], &fUV[1],pMesh->orco[indices[vert_index]][0], pMesh->orco[indices[vert_index]][1], pMesh->orco[indices[vert_index]][2]);
+	}
+}
+
+static void GetNormal(const SMikkTSpaceContext * pContext, float fNorm[], const int face_num, const int vert_index)
+{
+	//assert(vert_index>=0 && vert_index<4);
+	SGLSLMeshToTangent * pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+	unsigned int indices[] = {	pMesh->mface[face_num].v1, pMesh->mface[face_num].v2,
+								pMesh->mface[face_num].v3, pMesh->mface[face_num].v4 };
+
+	const int smoothnormal = (pMesh->mface[face_num].flag & ME_SMOOTH);
+	if(!smoothnormal)	// flat
+	{
+		if(pMesh->precomputedFaceNormals)
+		{
+			VECCOPY(fNorm, &pMesh->precomputedFaceNormals[3*face_num]);
+		}
+		else
+		{
+			float nor[3];
+			float * p0, * p1, * p2;
+			const int iGetNrVerts = pMesh->mface[face_num].v4!=0 ? 4 : 3;
+			p0 = pMesh->mvert[indices[0]].co; p1 = pMesh->mvert[indices[1]].co; p2 = pMesh->mvert[indices[2]].co;
+			if(iGetNrVerts==4)
+			{
+				float * p3 = pMesh->mvert[indices[3]].co;
+				normal_quad_v3( nor, p0, p1, p2, p3);
+			}
+			else {
+				normal_tri_v3(nor, p0, p1, p2);
+			}
+			VECCOPY(fNorm, nor);
+		}
+	}
+	else
+	{
+		int i=0;
+		short * no = pMesh->mvert[indices[vert_index]].no;
+		for(i=0; i<3; i++)
+			fNorm[i]=no[i]/32767.0f;
+		normalize_v3(fNorm);
+	}
+}
+static void SetTSpace(const SMikkTSpaceContext * pContext, const float fvTangent[], const float fSign, const int face_num, const int iVert)
+{
+	//assert(vert_index>=0 && vert_index<4);
+	SGLSLMeshToTangent * pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+	float * pRes = pMesh->tangent[4*face_num+iVert];
+	VECCOPY(pRes, fvTangent);
+	pRes[3]=fSign;
+}
+
+
 void DM_add_tangent_layer(DerivedMesh *dm)
 {
 	/* mesh vars */
@@ -2489,14 +2594,17 @@ void DM_add_tangent_layer(DerivedMesh *dm)
 	MVert *mvert, *v1, *v2, *v3, *v4;
 	MemArena *arena= NULL;
 	VertexTangent **vtangents= NULL;
-	float (*orco)[3]= NULL, (*tangent)[3];
+	float (*orco)[3]= NULL, (*tangent)[4];
 	float *uv1, *uv2, *uv3, *uv4, *vtang;
 	float fno[3], tang[3], uv[4][2];
-	int i, j, len, mf_vi[4], totvert, totface;
+	int i, j, len, mf_vi[4], totvert, totface, iCalcNewMethod;
+	float *nors;
 
 	if(CustomData_get_layer_index(&dm->faceData, CD_TANGENT) != -1)
 		return;
 
+	nors = dm->getFaceDataArray(dm, CD_NORMAL);
+
 	/* check we have all the needed layers */
 	totvert= dm->getNumVerts(dm);
 	totface= dm->getNumFaces(dm);
@@ -2519,72 +2627,108 @@ void DM_add_tangent_layer(DerivedMesh *dm)
 	arena= BLI_memarena_new(BLI_MEMARENA_STD_BUFSIZE, "tangent layer arena");
 	BLI_memarena_use_calloc(arena);
 	vtangents= MEM_callocN(sizeof(VertexTangent*)*totvert, "VertexTangent");
-	
-	/* sum tangents at connected vertices */
-	for(i=0, tf=mtface, mf=mface; i < totface; mf++, tf++, i++) {
-		v1= &mvert[mf->v1];
-		v2= &mvert[mf->v2];
-		v3= &mvert[mf->v3];
-
-		if (mf->v4) {
-			v4= &mvert[mf->v4];
-			normal_quad_v3( fno,v4->co, v3->co, v2->co, v1->co);
-		}
-		else {
-			v4= NULL;
-			normal_tri_v3( fno,v3->co, v2->co, v1->co);
-		}
-		
-		if(mtface) {
-			uv1= tf->uv[0];
-			uv2= tf->uv[1];
-			uv3= tf->uv[2];
-			uv4= tf->uv[3];
-		}
-		else {
-			uv1= uv[0]; uv2= uv[1]; uv3= uv[2]; uv4= uv[3];
-			map_to_sphere( &uv[0][0], &uv[0][1],orco[mf->v1][0], orco[mf->v1][1], orco[mf->v1][2]);
-			map_to_sphere( &uv[1][0], &uv[1][1],orco[mf->v2][0], orco[mf->v2][1], orco[mf->v2][2]);
-			map_to_sphere( &uv[2][0], &uv[2][1],orco[mf->v3][0], orco[mf->v3][1], orco[mf->v3][2]);
-			if(v4)
-				map_to_sphere( &uv[3][0], &uv[3][1],orco[mf->v4][0], orco[mf->v4][1], orco[mf->v4][2]);
-		}
+
+	// new computation method
+	iCalcNewMethod = 1;
+	if(iCalcNewMethod!=0)
+	{
+		SGLSLMeshToTangent mesh2tangent;
+		SMikkTSpaceContext sContext;
+		SMikkTSpaceInterface sInterface;
+		memset(&mesh2tangent, 0, sizeof(SGLSLMeshToTangent));
+		memset(&sContext, 0, sizeof(SMikkTSpaceContext));
+		memset(&sInterface, 0, sizeof(SMikkTSpaceInterface));
+
+		mesh2tangent.precomputedFaceNormals = nors;
+		mesh2tangent.mtface = mtface;
+		mesh2tangent.mface = mface;
+		mesh2tangent.mvert = mvert;
+		mesh2tangent.orco = orco;
+		mesh2tangent.tangent = tangent;
+		mesh2tangent.numFaces = totface;
+
+		sContext.m_pUserData = &mesh2tangent;
+		sContext.m_pInterface = &sInterface;
+		sInterface.m_getNumFaces = GetNumFaces;
+		sInterface.m_getNumVerticesOfFace = GetNumVertsOfFace;
+		sInterface.m_getPosition = GetPosition;
+		sInterface.m_getTexCoord = GetTextureCoordinate;
+		sInterface.m_getNormal = GetNormal;
+		sInterface.m_setTSpaceBasic = SetTSpace;
+
+		// 0 if failed
+		iCalcNewMethod = genTangSpaceDefault(&sContext);
+	}
+
+	if(!iCalcNewMethod)
+	{
+		/* sum tangents at connected vertices */
+		for(i=0, tf=mtface, mf=mface; i < totface; mf++, tf++, i++) {
+			v1= &mvert[mf->v1];
+			v2= &mvert[mf->v2];
+			v3= &mvert[mf->v3];
+
+			if (mf->v4) {
+				v4= &mvert[mf->v4];
+				normal_quad_v3( fno,v4->co, v3->co, v2->co, v1->co);
+			}
+			else {
+				v4= NULL;
+				normal_tri_v3( fno,v3->co, v2->co, v1->co);
+			}
 		
-		tangent_from_uv(uv1, uv2, uv3, v1->co, v2->co, v3->co, fno, tang);
-		sum_or_add_vertex_tangent(arena, &vtangents[mf->v1], tang, uv1);
-		sum_or_add_vertex_tangent(arena, &vtangents[mf->v2], tang, uv2);
-		sum_or_add_vertex_tangent(arena, &vtangents[mf->v3], tang, uv3);
+			if(mtface) {
+				uv1= tf->uv[0];
+				uv2= tf->uv[1];
+				uv3= tf->uv[2];
+				uv4= tf->uv[3];
+			}
+			else {
+				uv1= uv[0]; uv2= uv[1]; uv3= uv[2]; uv4= uv[3];
+				map_to_sphere( &uv[0][0], &uv[0][1],orco[mf->v1][0], orco[mf->v1][1], orco[mf->v1][2]);
+				map_to_sphere( &uv[1][0], &uv[1][1],orco[mf->v2][0], orco[mf->v2][1], orco[mf->v2][2]);
+				map_to_sphere( &uv[2][0], &uv[2][1],orco[mf->v3][0], orco[mf->v3][1], orco[mf->v3][2]);
+				if(v4)
+					map_to_sphere( &uv[3][0], &uv[3][1],orco[mf->v4][0], orco[mf->v4][1], orco[mf->v4][2]);
+			}
 		
-		if(mf->v4) {
-			v4= &mvert[mf->v4];
-			
-			tangent_from_uv(uv1, uv3, uv4, v1->co, v3->co, v4->co, fno, tang);
+			tangent_from_uv(uv1, uv2, uv3, v1->co, v2->co, v3->co, fno, tang);
 			sum_or_add_vertex_tangent(arena, &vtangents[mf->v1], tang, uv1);
+			sum_or_add_vertex_tangent(arena, &vtangents[mf->v2], tang, uv2);
 			sum_or_add_vertex_tangent(arena, &vtangents[mf->v3], tang, uv3);
-			sum_or_add_vertex_tangent(arena, &vtangents[mf->v4], tang, uv4);
+		
+			if(mf->v4) {
+				v4= &mvert[mf->v4];
+			
+				tangent_from_uv(uv1, uv3, uv4, v1->co, v3->co, v4->co, fno, tang);
+				sum_or_add_vertex_tangent(arena, &vtangents[mf->v1], tang, uv1);
+				sum_or_add_vertex_tangent(arena, &vtangents[mf->v3], tang, uv3);
+				sum_or_add_vertex_tangent(arena, &vtangents[mf->v4], tang, uv4);
+			}
 		}
-	}
 	
-	/* write tangent to layer */
-	for(i=0, tf=mtface, mf=mface; i < totface; mf++, tf++, i++, tangent+=4) {
-		len= (mf->v4)? 4 : 3; 
-
-		if(mtface == NULL) {
-			map_to_sphere( &uv[0][0], &uv[0][1],orco[mf->v1][0], orco[mf->v1][1], orco[mf->v1][2]);
-			map_to_sphere( &uv[1][0], &uv[1][1],orco[mf->v2][0], orco[mf->v2][1], orco[mf->v2][2]);
-			map_to_sphere( &uv[2][0], &uv[2][1],orco[mf->v3][0], orco[mf->v3][1], orco[mf->v3][2]);
-			if(len==4)
-				map_to_sphere( &uv[3][0], &uv[3][1],orco[mf->v4][0], orco[mf->v4][1], orco[mf->v4][2]);
-		}
+		/* write tangent to layer */
+		for(i=0, tf=mtface, mf=mface; i < totface; mf++, tf++, i++, tangent+=4) {
+			len= (mf->v4)? 4 : 3; 
+
+			if(mtface == NULL) {
+				map_to_sphere( &uv[0][0], &uv[0][1],orco[mf->v1][0], orco[mf->v1][1], orco[mf->v1][2]);
+				map_to_sphere( &uv[1][0], &uv[1][1],orco[mf->v2][0], orco[mf->v2][1], orco[mf->v2][2]);
+				map_to_sphere( &uv[2][0], &uv[2][1],orco[mf->v3][0], orco[mf->v3][1], orco[mf->v3][2]);
+				if(len==4)
+					map_to_sphere( &uv[3][0], &uv[3][1],orco[mf->v4][0], orco[mf->v4][1], orco[mf->v4][2]);
+			}
 		
-		mf_vi[0]= mf->v1;
-		mf_vi[1]= mf->v2;
-		mf_vi[2]= mf->v3;
-		mf_vi[3]= mf->v4;
+			mf_vi[0]= mf->v1;
+			mf_vi[1]= mf->v2;
+			mf_vi[2]= mf->v3;
+			mf_vi[3]= mf->v4;
 		
-		for(j=0; j<len; j++) {
-			vtang= find_vertex_tangent(vtangents[mf_vi[j]], mtface ? tf->uv[j] : uv[j]);
-			normalize_v3_v3(tangent[j], vtang);
+			for(j=0; j<len; j++) {
+				vtang= find_vertex_tangent(vtangents[mf_vi[j]], mtface ? tf->uv[j] : uv[j]);
+				normalize_v3_v3(tangent[j], vtang);
+				((float *) tangent[j])[3]=1.0f;
+			}
 		}
 	}
 	
diff --git a/source/blender/blenkernel/intern/cdderivedmesh.c b/source/blender/blenkernel/intern/cdderivedmesh.c
index abf2257877b..9a04c75db07 100644
--- a/source/blender/blenkernel/intern/cdderivedmesh.c
+++ b/source/blender/blenkernel/intern/cdderivedmesh.c
@@ -1066,7 +1066,7 @@ static void cdDM_drawMappedFacesGLSL(DerivedMesh *dm, int (*setMaterial)(int, vo
 		}																			\
 		if(attribs.tottang) {														\
 			float *tang = attribs.tang.array[a*4 + vert];							\
-			glVertexAttrib3fvARB(attribs.tang.glIndex, tang);						\
+			glVertexAttrib4fvARB(attribs.tang.glIndex, tang);						\
 		}																			\
 		if(smoothnormal)															\
 			glNormal3sv(mvert[index].no);											\
@@ -1158,7 +1158,7 @@ static void cdDM_drawMappedFacesGLSL(DerivedMesh *dm, int (*setMaterial)(int, vo
 						}	
 						if(attribs.tottang) {
 							datatypes[numdata].index = attribs.tang.glIndex;
-							datatypes[numdata].size = 3;
+							datatypes[numdata].size = 4;
 							datatypes[numdata].type = GL_FLOAT;
 							numdata++;
 						}
@@ -1248,12 +1248,12 @@ static void cdDM_drawMappedFacesGLSL(DerivedMesh *dm, int (*setMaterial)(int, vo
 					}	
 					if(attribs.tottang) {
 						float *tang = attribs.tang.array[a*4 + 0];
-						VECCOPY((float *)&varray[elementsize*curface*3+offset], tang);
+						QUATCOPY((float *)&varray[elementsize*curface*3+offset], tang);
 						tang = attribs.tang.array[a*4 + 1];
-						VECCOPY((float *)&varray[elementsize*curface*3+offset+elementsize], tang);
+						QUATCOPY((float *)&varray[elementsize*curface*3+offset+elementsize], tang);
 						tang = attribs.tang.array[a*4 + 2];
-						VECCOPY((float *)&varray[elementsize*curface*3+offset+elementsize*2], tang);
-						offset += sizeof(float)*3;
+						QUATCOPY((float *)&varray[elementsize*curface*3+offset+elementsize*2], tang);
+						offset += sizeof(float)*4;
 					}
 				}
 				curface++;
@@ -1288,12 +1288,12 @@ static void cdDM_drawMappedFacesGLSL(DerivedMesh *dm, int (*setMaterial)(int, vo
 						}	
 						if(attribs.tottang) {
 							float *tang = attribs.tang.array[a*4 + 2];
-							VECCOPY((float *)&varray[elementsize*curface*3+offset], tang);
+							QUATCOPY((float *)&varray[elementsize*curface*3+offset], tang);
 							tang = attribs.tang.array[a*4 + 3];
-							VECCOPY((float *)&varray[elementsize*curface*3+offset+elementsize], tang);
+							QUATCOPY((float *)&varray[elementsize*curface*3+offset+elementsize], tang);
 							tang = attribs.tang.array[a*4 + 0];
-							VECCOPY((float *)&varray[elementsize*curface*3+offset+elementsize*2], tang);
-							offset += sizeof(float)*3;
+							QUATCOPY((float *)&varray[elementsize*curface*3+offset+elementsize*2], tang);
+							offset += sizeof(float)*4;
 						}
 					}
 					curface++;
diff --git a/source/blender/blenkernel/intern/customdata.c b/source/blender/blenkernel/intern/customdata.c
index 7788f9f28a2..87fe545644a 100644
--- a/source/blender/blenkernel/intern/customdata.c
+++ b/source/blender/blenkernel/intern/customdata.c
@@ -829,7 +829,7 @@ static const LayerTypeInfo LAYERTYPEINFO[CD_NUMTYPES] = {
 	{sizeof(MTexPoly), "MTexPoly", 1, "Face Texture", NULL, NULL, NULL, NULL, NULL},
 	{sizeof(MLoopUV), "MLoopUV", 1, "UV coord", NULL, NULL, layerInterp_mloopuv, NULL, NULL},
 	{sizeof(MLoopCol), "MLoopCol", 1, "Col", NULL, NULL, layerInterp_mloopcol, NULL, layerDefault_mloopcol},
-	{sizeof(float)*3*4, "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
+	{sizeof(float)*4*4, "", 0, NULL, NULL, NULL, NULL, NULL, NULL},
 	{sizeof(MDisps), "MDisps", 1, NULL, layerCopy_mdisps,
 	 layerFree_mdisps, layerInterp_mdisps, layerSwap_mdisps, NULL, layerRead_mdisps, layerWrite_mdisps,
 	 layerFilesize_mdisps, layerValidate_mdisps},
diff --git a/source/blender/blenkernel/intern/mikktspace.c b/source/blender/blenkernel/intern/mikktspace.c
new file mode 100644
index 00000000000..83623a13db8
--- /dev/null
+++ b/source/blender/blenkernel/intern/mikktspace.c
@@ -0,0 +1,1886 @@
+/**
+ *  Copyright (C) 2011 by Morten S. Mikkelsen
+ *
+ *  This software is provided 'as-is', without any express or implied
+ *  warranty.  In no event will the authors be held liable for any damages
+ *  arising from the use of this software.
+ *
+ *  Permission is granted to anyone to use this software for any purpose,
+ *  including commercial applications, and to alter it and redistribute it
+ *  freely, subject to the following restrictions:
+ *
+ *  1. The origin of this software must not be misrepresented; you must not
+ *     claim that you wrote the original software. If you use this software
+ *     in a product, an acknowledgment in the product documentation would be
+ *     appreciated but is not required.
+ *  2. Altered source versions must be plainly marked as such, and must not be
+ *     misrepresented as being the original software.
+ *  3. This notice may not be removed or altered from any source distribution.
+ */
+
+#include <assert.h>
+#include <stdio.h>
+#include <math.h>
+#include <string.h>
+#include <float.h>
+#include <malloc.h>
+#include "mikktspace.h"
+
+#define TFALSE		0
+#define TTRUE		1
+
+#ifndef M_PI
+#define M_PI	3.1415926535897932384626433832795
+#endif
+
+#define INTERNAL_RND_SORT_SEED		39871946
+
+// internal structure
+typedef struct
+{
+	float x, y, z;
+} SVec3;
+
+tbool			veq( const SVec3 v1, const SVec3 v2 )
+{
+	return (v1.x == v2.x) && (v1.y == v2.y) && (v1.z == v2.z);
+}
+
+const SVec3		vadd( const SVec3 v1, const SVec3 v2 )
+{
+	SVec3 vRes;
+
+	vRes.x = v1.x + v2.x;
+	vRes.y = v1.y + v2.y;
+	vRes.z = v1.z + v2.z;
+
+	return vRes;
+}
+
+
+const SVec3		vsub( const SVec3 v1, const SVec3 v2 )
+{
+	SVec3 vRes;
+
+	vRes.x = v1.x - v2.x;
+	vRes.y = v1.y - v2.y;
+	vRes.z = v1.z - v2.z;
+
+	return vRes;
+}
+
+const SVec3		vscale(const float fS, const SVec3 v)
+{
+	SVec3 vRes;
+
+	vRes.x = fS * v.x;
+	vRes.y = fS * v.y;
+	vRes.z = fS * v.z;
+
+	return vRes;
+}
+
+float			LengthSquared( const SVec3 v )
+{
+	return v.x*v.x + v.y*v.y + v.z*v.z;
+}
+
+float			Length( const SVec3 v )
+{
+	return sqrtf(LengthSquared(v));
+}
+
+const SVec3		Normalize( const SVec3 v )
+{
+	return vscale(1 / Length(v), v);
+}
+
+const float		vdot( const SVec3 v1, const SVec3 v2)
+{
+	return v1.x*v2.x + v1.y*v2.y + v1.z*v2.z;
+}
+
+
+tbool NotZero(const float fX)
+{
+	// could possibly use FLT_EPSILON instead
+	return fabsf(fX) > FLT_MIN;
+}
+
+tbool VNotZero(const SVec3 v)
+{
+	// might change this to an epsilon based test
+	return NotZero(v.x) || NotZero(v.y) || NotZero(v.z);
+}
+
+
+
+typedef struct
+{
+	int iNrFaces;
+	int * pTriMembers;
+} SSubGroup;
+
+typedef struct
+{
+	int iNrFaces;
+	int * pFaceIndices;
+	int iVertexRepresentitive;
+	tbool bOrientPreservering;
+} SGroup;
+
+// 
+#define MARK_DEGENERATE				1
+#define QUAD_ONE_DEGEN_TRI			2
+#define GROUP_WITH_ANY				4
+#define ORIENT_PRESERVING			8
+
+
+
+typedef struct
+{
+	int FaceNeighbors[3];
+	SGroup * AssignedGroup[3];
+	
+	// normalized first order face derivatives
+	SVec3 vOs, vOt;
+	float fMagS, fMagT;	// original magnitudes
+
+	// determines if the current and the next triangle are a quad.
+	int iOrgFaceNumber;
+	int iFlag, iTSpacesOffs;
+	unsigned char vert_num[4];
+} STriInfo;
+
+typedef struct
+{
+	SVec3 vOs;
+	float fMagS;
+	SVec3 vOt;
+	float fMagT;
+	int iCounter;	// this is to average back into quads.
+	tbool bOrient;
+} STSpace;
+
+int GenerateInitialVerticesIndexList(STriInfo pTriInfos[], int piTriList_out[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn);
+void GenerateSharedVerticesIndexList(int piTriList_in_and_out[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn);
+void InitTriInfo(STriInfo pTriInfos[], const int piTriListIn[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn);
+int Build4RuleGroups(STriInfo pTriInfos[], SGroup pGroups[], int piGroupTrianglesBuffer[], const int piTriListIn[], const int iNrTrianglesIn);
+tbool GenerateTSpaces(STSpace psTspace[], const STriInfo pTriInfos[], const SGroup pGroups[],
+					 const int iNrActiveGroups, const int piTriListIn[], const float fThresCos,
+					 const SMikkTSpaceContext * pContext);
+
+int MakeIndex(const int iFace, const int iVert)
+{
+	assert(iVert>=0 && iVert<4 && iFace>=0);
+	return (iFace<<2) | (iVert&0x3);
+}
+
+void IndexToData(int * piFace, int * piVert, const int iIndexIn)
+{
+	piVert[0] = iIndexIn&0x3;
+	piFace[0] = iIndexIn>>2;
+}
+
+const STSpace AvgTSpace(const STSpace * pTS0, const STSpace * pTS1)
+{
+	STSpace ts_res;
+
+	// this if is important. Due to floating point precision
+	// averaging when ts0==ts1 will cause a slight difference
+	// which results in tangent space splits later on
+	if(pTS0->fMagS==pTS1->fMagS && pTS0->fMagT==pTS1->fMagT &&
+	   veq(pTS0->vOs,pTS1->vOs)	&& veq(pTS0->vOt, pTS1->vOt))
+	{
+		ts_res.fMagS = pTS0->fMagS;
+		ts_res.fMagT = pTS0->fMagT;
+		ts_res.vOs = pTS0->vOs;
+		ts_res.vOt = pTS0->vOt;
+	}
+	else
+	{
+		ts_res.fMagS = 0.5f*(pTS0->fMagS+pTS1->fMagS);
+		ts_res.fMagT = 0.5f*(pTS0->fMagT+pTS1->fMagT);
+		ts_res.vOs = vadd(pTS0->vOs,pTS1->vOs);
+		ts_res.vOt = vadd(pTS0->vOt,pTS1->vOt);
+		if( VNotZero(ts_res.vOs) ) ts_res.vOs = Normalize(ts_res.vOs);
+		if( VNotZero(ts_res.vOt) ) ts_res.vOt = Normalize(ts_res.vOt);
+	}
+
+	return ts_res;
+}
+
+
+
+const SVec3 GetPosition(const SMikkTSpaceContext * pContext, const int index);
+const SVec3 GetNormal(const SMikkTSpaceContext * pContext, const int index);
+const SVec3 GetTexCoord(const SMikkTSpaceContext * pContext, const int index);
+
+
+// degen triangles
+void DegenPrologue(STriInfo pTriInfos[], int piTriList_out[], const int iNrTrianglesIn, const int iTotTris);
+void DegenEpilogue(STSpace psTspace[], STriInfo pTriInfos[], int piTriListIn[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn, const int iTotTris);
+
+
+tbool genTangSpaceDefault(const SMikkTSpaceContext * pContext)
+{
+	return genTangSpace(pContext, 180.0f);
+}
+
+tbool genTangSpace(const SMikkTSpaceContext * pContext, const float fAngularThreshold)
+{
+	// count nr_triangles
+	int * piTriListIn = NULL, * piGroupTrianglesBuffer = NULL;
+	STriInfo * pTriInfos = NULL;
+	SGroup * pGroups = NULL;
+	STSpace * psTspace = NULL;
+	int iNrTrianglesIn = 0, f=0, t=0, i=0;
+	int iNrTSPaces = 0, iTotTris = 0, iDegenTriangles = 0, iNrMaxGroups = 0;
+	int iNrActiveGroups = 0, index = 0;
+	const int iNrFaces = pContext->m_pInterface->m_getNumFaces(pContext);
+	tbool bRes = TFALSE;
+	const float fThresCos = (const float) cos((fAngularThreshold*M_PI)/180);
+
+	// verify all call-backs have been set
+	if( pContext->m_pInterface->m_getNumFaces==NULL ||
+		pContext->m_pInterface->m_getNumVerticesOfFace==NULL ||
+		pContext->m_pInterface->m_getPosition==NULL ||
+		pContext->m_pInterface->m_getNormal==NULL ||
+		pContext->m_pInterface->m_getTexCoord==NULL )
+		return TFALSE;
+
+	// count triangles on supported faces
+	for(f=0; f<iNrFaces; f++)
+	{
+		const int verts = pContext->m_pInterface->m_getNumVerticesOfFace(pContext, f);
+		if(verts==3) ++iNrTrianglesIn;
+		else if(verts==4) iNrTrianglesIn += 2;
+	}
+	if(iNrTrianglesIn<=0) return TFALSE;
+
+	// allocate memory for an index list
+	piTriListIn = (int *) malloc(sizeof(int)*3*iNrTrianglesIn);
+	pTriInfos = (STriInfo *) malloc(sizeof(STriInfo)*iNrTrianglesIn);
+	if(piTriListIn==NULL || pTriInfos==NULL)
+	{
+		if(piTriListIn!=NULL) free(piTriListIn);
+		if(pTriInfos!=NULL) free(pTriInfos);
+		return TFALSE;
+	}
+
+	// make an initial triangle --> face index list
+	iNrTSPaces = GenerateInitialVerticesIndexList(pTriInfos, piTriListIn, pContext, iNrTrianglesIn);
+
+	// make a welded index list of identical positions and attributes (pos, norm, texc)
+	//printf("gen welded index list begin\n");
+	GenerateSharedVerticesIndexList(piTriListIn, pContext, iNrTrianglesIn);
+	//printf("gen welded index list end\n");
+
+	// Mark all degenerate triangles
+	iTotTris = iNrTrianglesIn;
+	iNrTrianglesIn = 0;
+	iDegenTriangles = 0;
+	for(t=0; t<iTotTris; t++)
+	{
+		const int i0 = piTriListIn[t*3+0];
+		const int i1 = piTriListIn[t*3+1];
+		const int i2 = piTriListIn[t*3+2];
+		const SVec3 p0 = GetPosition(pContext, i0);
+		const SVec3 p1 = GetPosition(pContext, i1);
+		const SVec3 p2 = GetPosition(pContext, i2);
+		if(veq(p0,p1) || veq(p0,p2) || veq(p1,p2))	// degenerate
+		{
+			pTriInfos[t].iFlag |= MARK_DEGENERATE;
+			++iDegenTriangles;
+		}
+	}
+	iNrTrianglesIn = iTotTris - iDegenTriangles;
+
+	// mark all triangle pairs that belong to a quad with only one
+	// good triangle. These need special treatment in DegenEpilogue().
+	// Additionally, move all good triangles to the start of
+	// pTriInfos[] and piTriListIn[] without changing order and
+	// put the degenerate triangles last.
+	DegenPrologue(pTriInfos, piTriListIn, iNrTrianglesIn, iTotTris);
+
+	
+	// evaluate triangle level attributes and neighbor list
+	//printf("gen neighbors list begin\n");
+	InitTriInfo(pTriInfos, piTriListIn, pContext, iNrTrianglesIn);
+	//printf("gen neighbors list end\n");
+
+	
+	// based on the 4 rules, identify groups based on connectivity
+	iNrMaxGroups = iNrTrianglesIn*3;
+	pGroups = (SGroup *) malloc(sizeof(SGroup)*iNrMaxGroups);
+	piGroupTrianglesBuffer = (int *) malloc(sizeof(int)*iNrTrianglesIn*3);
+	if(pGroups==NULL || piGroupTrianglesBuffer==NULL)
+	{
+		if(pGroups!=NULL) free(pGroups);
+		if(piGroupTrianglesBuffer!=NULL) free(piGroupTrianglesBuffer);
+		free(piTriListIn);
+		free(pTriInfos);
+		return TFALSE;
+	}
+	//printf("gen 4rule groups begin\n");
+	iNrActiveGroups =
+		Build4RuleGroups(pTriInfos, pGroups, piGroupTrianglesBuffer, piTriListIn, iNrTrianglesIn);
+	//printf("gen 4rule groups end\n");
+
+	//
+
+	psTspace = (STSpace *) malloc(sizeof(STSpace)*iNrTSPaces);
+	if(psTspace==NULL)
+	{
+		free(piTriListIn);
+		free(pTriInfos);
+		free(pGroups);
+		free(piGroupTrianglesBuffer);
+		return TFALSE;
+	}
+	memset(psTspace, 0, sizeof(STSpace)*iNrTSPaces);
+	for(t=0; t<iNrTSPaces; t++)
+	{
+		psTspace[t].vOs.x=1.0f; psTspace[t].vOs.y=0.0f; psTspace[t].vOs.z=0.0f; psTspace[t].fMagS = 1.0f;
+		psTspace[t].vOt.x=0.0f; psTspace[t].vOt.y=1.0f; psTspace[t].vOt.z=0.0f; psTspace[t].fMagT = 1.0f;
+	}
+
+	// make tspaces, each group is split up into subgroups if necessary
+	// based on fAngularThreshold. Finally a tangent space is made for
+	// every resulting subgroup
+	//printf("gen tspaces begin\n");
+	bRes = GenerateTSpaces(psTspace, pTriInfos, pGroups, iNrActiveGroups, piTriListIn, fThresCos, pContext);
+	//printf("gen tspaces end\n");
+	
+	// clean up
+	free(pGroups);
+	free(piGroupTrianglesBuffer);
+
+	if(!bRes)	// if an allocation in GenerateTSpaces() failed
+	{
+		// clean up and return false
+		free(pTriInfos); free(piTriListIn); free(psTspace);
+		return TFALSE;
+	}
+
+
+	// degenerate quads with one good triangle will be fixed by copying a space from
+	// the good triangle to the coinciding vertex.
+	// all other degenerate triangles will just copy a space from any good triangle
+	// with the same welded index in piTriListIn[].
+	DegenEpilogue(psTspace, pTriInfos, piTriListIn, pContext, iNrTrianglesIn, iTotTris);
+
+	free(pTriInfos); free(piTriListIn);
+
+	index = 0;
+	for(f=0; f<iNrFaces; f++)
+	{
+		const int verts = pContext->m_pInterface->m_getNumVerticesOfFace(pContext, f);
+		if(verts!=3 && verts!=4) continue;
+		
+
+		// I've decided to let degenerate triangles and group-with-anythings
+		// vary between left/right hand coordinate systems at the vertices.
+		// All healthy triangles on the other hand are built to always be either or.
+
+		/*// force the coordinate system orientation to be uniform for every face.
+		// (this is already the case for good triangles but not for
+		// degenerate ones and those with bGroupWithAnything==true)
+		bool bOrient = psTspace[index].bOrient;
+		if(psTspace[index].iCounter == 0)	// tspace was not derived from a group
+		{
+			// look for a space created in GenerateTSpaces() by iCounter>0
+			bool bNotFound = true;
+			int i=1;
+			while(i<verts && bNotFound)
+			{
+				if(psTspace[index+i].iCounter > 0) bNotFound=false;
+				else ++i;
+			}
+			if(!bNotFound) bOrient = psTspace[index+i].bOrient;
+		}*/
+
+		// set data
+		for(i=0; i<verts; i++)
+		{
+			const STSpace * pTSpace = &psTspace[index];
+			float tang[] = {pTSpace->vOs.x, pTSpace->vOs.y, pTSpace->vOs.z};
+			float bitang[] = {pTSpace->vOt.x, pTSpace->vOt.y, pTSpace->vOt.z};
+			if(pContext->m_pInterface->m_setTSpace!=NULL)
+				pContext->m_pInterface->m_setTSpace(pContext, tang, bitang, pTSpace->fMagS, pTSpace->fMagT, pTSpace->bOrient, f, i);
+			if(pContext->m_pInterface->m_setTSpaceBasic!=NULL)
+				pContext->m_pInterface->m_setTSpaceBasic(pContext, tang, pTSpace->bOrient==TTRUE ? 1.0f : (-1.0f), f, i);
+
+			++index;
+		}
+	}
+
+	free(psTspace);
+
+	
+	return TTRUE;
+}
+
+///////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+typedef struct
+{
+	float vert[3];
+	int index;
+} STmpVert;
+
+const int g_iCells = 2048;
+
+// it is IMPORTANT that this function is called to evaluate the hash since
+// inlining could potentially reorder instructions and generate different
+// results for the same effective input value fVal.
+volatile int FindGridCell(const float fMin, const float fMax, const float fVal)
+{
+	const float fIndex = (g_iCells-1) * ((fVal-fMin)/(fMax-fMin));
+	const int iIndex = fIndex<0?0:((int) (fIndex+0.5f));
+	return iIndex<g_iCells?iIndex:(g_iCells-1);
+}
+
+void MergeVertsFast(int piTriList_in_and_out[], STmpVert pTmpVert[], const SMikkTSpaceContext * pContext, const int iL_in, const int iR_in);
+void MergeVertsSlow(int piTriList_in_and_out[], const SMikkTSpaceContext * pContext, const int pTable[], const int iEntries);
+void GenerateSharedVerticesIndexListSlow(int piTriList_in_and_out[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn);
+
+void GenerateSharedVerticesIndexList(int piTriList_in_and_out[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn)
+{
+
+	// Generate bounding box
+	int * piHashTable=NULL, * piHashCount=NULL, * piHashOffsets=NULL, * piHashCount2=NULL;
+	STmpVert * pTmpVert = NULL;
+	int i=0, iChannel=0, k=0, e=0;
+	int iMaxCount=0;
+	SVec3 vMin = GetPosition(pContext, 0), vMax = vMin, vDim;
+	float fMin, fMax;
+	for(i=1; i<(iNrTrianglesIn*3); i++)
+	{
+		const int index = piTriList_in_and_out[i];
+
+		const SVec3 vP = GetPosition(pContext, index);
+		if(vMin.x > vP.x) vMin.x = vP.x;
+		else if(vMax.x < vP.x) vMax.x = vP.x;
+		if(vMin.y > vP.y) vMin.y = vP.y;
+		else if(vMax.y < vP.y) vMax.y = vP.y;
+		if(vMin.z > vP.z) vMin.z = vP.z;
+		else if(vMax.z < vP.z) vMax.z = vP.z;
+	}
+
+	vDim = vsub(vMax,vMin);
+	iChannel = 0;
+	fMin = vMin.x; fMax=vMax.x;
+	if(vDim.y>vDim.x && vDim.y>vDim.z)
+	{
+		iChannel=1;
+		fMin = vMin.y, fMax=vMax.y;
+	}
+	else if(vDim.z>vDim.x)
+	{
+		iChannel=2;
+		fMin = vMin.z, fMax=vMax.z;
+	}
+
+	// make allocations
+	piHashTable = (int *) malloc(sizeof(int)*iNrTrianglesIn*3);
+	piHashCount = (int *) malloc(sizeof(int)*g_iCells);
+	piHashOffsets = (int *) malloc(sizeof(int)*g_iCells);
+	piHashCount2 = (int *) malloc(sizeof(int)*g_iCells);
+
+	if(piHashTable==NULL || piHashCount==NULL || piHashOffsets==NULL || piHashCount2==NULL)
+	{
+		if(piHashTable!=NULL) free(piHashTable);
+		if(piHashCount!=NULL) free(piHashCount);
+		if(piHashOffsets!=NULL) free(piHashOffsets);
+		if(piHashCount2!=NULL) free(piHashCount2);
+		GenerateSharedVerticesIndexListSlow(piTriList_in_and_out, pContext, iNrTrianglesIn);
+		return;
+	}
+	memset(piHashCount, 0, sizeof(int)*g_iCells);
+	memset(piHashCount2, 0, sizeof(int)*g_iCells);
+
+	// count amount of elements in each cell unit
+	for(i=0; i<(iNrTrianglesIn*3); i++)
+	{
+		const int index = piTriList_in_and_out[i];
+		const SVec3 vP = GetPosition(pContext, index);
+		const float fVal = iChannel==0 ? vP.x : (iChannel==1 ? vP.y : vP.z);
+		const int iCell = FindGridCell(fMin, fMax, fVal);
+		++piHashCount[iCell];
+	}
+
+	// evaluate start index of each cell.
+	piHashOffsets[0]=0;
+	for(k=1; k<g_iCells; k++)
+		piHashOffsets[k]=piHashOffsets[k-1]+piHashCount[k-1];
+
+	// insert vertices
+	for(i=0; i<(iNrTrianglesIn*3); i++)
+	{
+		const int index = piTriList_in_and_out[i];
+		const SVec3 vP = GetPosition(pContext, index);
+		const float fVal = iChannel==0 ? vP.x : (iChannel==1 ? vP.y : vP.z);
+		const int iCell = FindGridCell(fMin, fMax, fVal);
+		int * pTable = NULL;
+
+		assert(piHashCount2[iCell]<piHashCount[iCell]);
+		pTable = &piHashTable[piHashOffsets[iCell]];
+		pTable[piHashCount2[iCell]] = i;	// vertex i has been inserted.
+		++piHashCount2[iCell];
+	}
+	for(k=0; k<g_iCells; k++)
+		assert(piHashCount2[k] == piHashCount[k]);	// verify the count
+	free(piHashCount2);
+
+	// find maximum amount of entries in any hash entry
+	iMaxCount = piHashCount[0];
+	for(k=1; k<g_iCells; k++)
+		if(iMaxCount<piHashCount[k])
+			iMaxCount=piHashCount[k];
+	pTmpVert = (STmpVert *) malloc(sizeof(STmpVert)*iMaxCount);
+	
+
+	// complete the merge
+	for(k=0; k<g_iCells; k++)
+	{
+		// extract table of cell k and amount of entries in it
+		int * pTable = &piHashTable[piHashOffsets[k]];
+		const int iEntries = piHashCount[k];
+		if(iEntries < 2) continue;
+
+		if(pTmpVert!=NULL)
+		{
+			for(e=0; e<iEntries; e++)
+			{
+				int i = pTable[e];
+				const SVec3 vP = GetPosition(pContext, piTriList_in_and_out[i]);
+				pTmpVert[e].vert[0] = vP.x; pTmpVert[e].vert[1] = vP.y;
+				pTmpVert[e].vert[2] = vP.z; pTmpVert[e].index = i;
+			}
+			MergeVertsFast(piTriList_in_and_out, pTmpVert, pContext, 0, iEntries-1);
+		}
+		else
+			MergeVertsSlow(piTriList_in_and_out, pContext, pTable, iEntries);
+	}
+
+	if(pTmpVert!=NULL) { free(pTmpVert); }
+	free(piHashTable);
+	free(piHashCount);
+	free(piHashOffsets);
+}
+
+void MergeVertsFast(int piTriList_in_and_out[], STmpVert pTmpVert[], const SMikkTSpaceContext * pContext, const int iL_in, const int iR_in)
+{
+	// make bbox
+	int c=0, l=0, channel=0;
+	float fvMin[3], fvMax[3];
+	float dx=0, dy=0, dz=0, fSep=0;
+	for(c=0; c<3; c++)
+	{	fvMin[c]=pTmpVert[iL_in].vert[c]; fvMax[c]=fvMin[c];	}
+	for(l=(iL_in+1); l<=iR_in; l++)
+		for(c=0; c<3; c++)
+			if(fvMin[c]>pTmpVert[l].vert[c]) fvMin[c]=pTmpVert[l].vert[c];
+			else if(fvMax[c]<pTmpVert[l].vert[c]) fvMax[c]=pTmpVert[l].vert[c];
+
+	dx = fvMax[0]-fvMin[0];
+	dy = fvMax[1]-fvMin[1];
+	dz = fvMax[2]-fvMin[2];
+
+	channel = 0;
+	if(dy>dx && dy>dz) channel=1;
+	else if(dz>dx) channel=2;
+
+	fSep = 0.5f*(fvMax[channel]+fvMin[channel]);
+
+	// terminate recursion when the separation/average value
+	// is no longer strictly between fMin and fMax values.
+	if(fSep>=fvMax[channel] || fSep<=fvMin[channel])
+	{
+		// complete the weld
+		for(l=iL_in; l<=iR_in; l++)
+		{
+			int i = pTmpVert[l].index;
+			const int index = piTriList_in_and_out[i];
+			const SVec3 vP = GetPosition(pContext, index);
+			const SVec3 vN = GetNormal(pContext, index);
+			const SVec3 vT = GetTexCoord(pContext, index);
+
+			tbool bNotFound = TTRUE;
+			int l2=iL_in, i2rec=-1;
+			while(l2<l && bNotFound)
+			{
+				const int i2 = pTmpVert[l2].index;
+				const int index2 = piTriList_in_and_out[i2];
+				const SVec3 vP2 = GetPosition(pContext, index2);
+				const SVec3 vN2 = GetNormal(pContext, index2);
+				const SVec3 vT2 = GetTexCoord(pContext, index2);
+				i2rec=i2;
+
+				//if(vP==vP2 && vN==vN2 && vT==vT2)
+				if(vP.x==vP2.x && vP.y==vP2.y && vP.z==vP2.z &&
+					vN.x==vN2.x && vN.y==vN2.y && vN.z==vN2.z &&
+					vT.x==vT2.x && vT.y==vT2.y && vT.z==vT2.z)
+					bNotFound = TFALSE;
+				else
+					++l2;
+			}
+			
+			// merge if previously found
+			if(!bNotFound)
+				piTriList_in_and_out[i] = piTriList_in_and_out[i2rec];
+		}
+	}
+	else
+	{
+		int iL=iL_in, iR=iR_in;
+		assert((iR_in-iL_in)>0);	// at least 2 entries
+
+		// seperate (by fSep) all points between iL_in and iR_in in pTmpVert[]
+		while(iL < iR)
+		{
+			tbool bReadyLeftSwap = TFALSE, bReadyRightSwap = TFALSE;
+			while((!bReadyLeftSwap) && iL<iR)
+			{
+				assert(iL>=iL_in && iL<=iR_in);
+				bReadyLeftSwap = !(pTmpVert[iL].vert[channel]<fSep);
+				if(!bReadyLeftSwap) ++iL;
+			}
+			while((!bReadyRightSwap) && iL<iR)
+			{
+				assert(iR>=iL_in && iR<=iR_in);
+				bReadyRightSwap = pTmpVert[iR].vert[channel]<fSep;
+				if(!bReadyRightSwap) --iR;
+			}
+			assert( (iL<iR) || !(bReadyLeftSwap && bReadyRightSwap) );
+
+			if(bReadyLeftSwap && bReadyRightSwap)
+			{
+				const STmpVert sTmp = pTmpVert[iL];
+				assert(iL<iR);
+				pTmpVert[iL] = pTmpVert[iR];
+				pTmpVert[iR] = sTmp;
+				++iL; --iR;
+			}
+		}
+
+		assert(iL==(iR+1) || (iL==iR));
+		if(iL==iR)
+		{
+			const tbool bReadyRightSwap = pTmpVert[iR].vert[channel]<fSep;
+			if(bReadyRightSwap) ++iL;
+			else --iR;
+		}
+
+		// only need to weld when there is more than 1 instance of the (x,y,z)
+		if(iL_in < iR)
+			MergeVertsFast(piTriList_in_and_out, pTmpVert, pContext, iL_in, iR);	// weld all left of fSep
+		if(iL < iR_in)
+			MergeVertsFast(piTriList_in_and_out, pTmpVert, pContext, iL, iR_in);	// weld all right of (or equal to) fSep
+	}
+}
+
+void MergeVertsSlow(int piTriList_in_and_out[], const SMikkTSpaceContext * pContext, const int pTable[], const int iEntries)
+{
+	// this can be optimized further using a tree structure or more hashing.
+	int e=0;
+	for(e=0; e<iEntries; e++)
+	{
+		int i = pTable[e];
+		const int index = piTriList_in_and_out[i];
+		const SVec3 vP = GetPosition(pContext, index);
+		const SVec3 vN = GetNormal(pContext, index);
+		const SVec3 vT = GetTexCoord(pContext, index);
+
+		tbool bNotFound = TTRUE;
+		int e2=0, i2rec=-1;
+		while(e2<e && bNotFound)
+		{
+			const int i2 = pTable[e2];
+			const int index2 = piTriList_in_and_out[i2];
+			const SVec3 vP2 = GetPosition(pContext, index2);
+			const SVec3 vN2 = GetNormal(pContext, index2);
+			const SVec3 vT2 = GetTexCoord(pContext, index2);
+			i2rec = i2;
+
+			if(veq(vP,vP2) && veq(vN,vN2) && veq(vT,vT2))
+				bNotFound = TFALSE;
+			else
+				++e2;
+		}
+		
+		// merge if previously found
+		if(!bNotFound)
+			piTriList_in_and_out[i] = piTriList_in_and_out[i2rec];
+	}
+}
+
+void GenerateSharedVerticesIndexListSlow(int piTriList_in_and_out[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn)
+{
+	int iNumUniqueVerts = 0, t=0, i=0;
+	for(t=0; t<iNrTrianglesIn; t++)
+	{
+		for(i=0; i<3; i++)
+		{
+			const int offs = t*3 + i;
+			const int index = piTriList_in_and_out[offs];
+
+			const SVec3 vP = GetPosition(pContext, index);
+			const SVec3 vN = GetNormal(pContext, index);
+			const SVec3 vT = GetTexCoord(pContext, index);
+
+			tbool bFound = TFALSE;
+			int t2=0, index2rec=-1;
+			while(!bFound && t2<=t)
+			{
+				int j=0;
+				while(!bFound && j<3)
+				{
+					const int index2 = piTriList_in_and_out[t2*3 + j];
+					const SVec3 vP2 = GetPosition(pContext, index2);
+					const SVec3 vN2 = GetNormal(pContext, index2);
+					const SVec3 vT2 = GetTexCoord(pContext, index2);
+					
+					if(veq(vP,vP2) && veq(vN,vN2) && veq(vT,vT2))
+						bFound = TTRUE;
+					else
+						++j;
+				}
+				if(!bFound) ++t2;
+			}
+
+			assert(bFound);
+			// if we found our own
+			if(index2rec == index) { ++iNumUniqueVerts; }
+
+			piTriList_in_and_out[offs] = index2rec;
+		}
+	}
+}
+
+int GenerateInitialVerticesIndexList(STriInfo pTriInfos[], int piTriList_out[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn)
+{
+	int iTSpacesOffs = 0, f=0, t=0;
+	int iDstTriIndex = 0;
+	for(f=0; f<pContext->m_pInterface->m_getNumFaces(pContext); f++)
+	{
+		const int verts = pContext->m_pInterface->m_getNumVerticesOfFace(pContext, f);
+		if(verts!=3 && verts!=4) continue;
+
+		pTriInfos[iDstTriIndex].iOrgFaceNumber = f;
+		pTriInfos[iDstTriIndex].iTSpacesOffs = iTSpacesOffs;
+
+		if(verts==3)
+		{
+			unsigned char * pVerts = pTriInfos[iDstTriIndex].vert_num;
+			pVerts[0]=0; pVerts[1]=1; pVerts[2]=2;
+			piTriList_out[iDstTriIndex*3+0] = MakeIndex(f, 0);
+			piTriList_out[iDstTriIndex*3+1] = MakeIndex(f, 1);
+			piTriList_out[iDstTriIndex*3+2] = MakeIndex(f, 2);
+			++iDstTriIndex;	// next
+		}
+		else
+		{
+			{
+				pTriInfos[iDstTriIndex+1].iOrgFaceNumber = f;
+				pTriInfos[iDstTriIndex+1].iTSpacesOffs = iTSpacesOffs;
+			}
+
+			{
+				// need an order independent way to evaluate
+				// tspace on quads. This is done by splitting
+				// along the shortest diagonal.
+				const int i0 = MakeIndex(f, 0);
+				const int i1 = MakeIndex(f, 1);
+				const int i2 = MakeIndex(f, 2);
+				const int i3 = MakeIndex(f, 3);
+				const SVec3 T0 = GetTexCoord(pContext, i0);
+				const SVec3 T1 = GetTexCoord(pContext, i1);
+				const SVec3 T2 = GetTexCoord(pContext, i2);
+				const SVec3 T3 = GetTexCoord(pContext, i3);
+				const float distSQ_02 = LengthSquared(vsub(T2,T0));
+				const float distSQ_13 = LengthSquared(vsub(T3,T1));
+				tbool bQuadDiagIs_02;
+				if(distSQ_02<distSQ_13)
+					bQuadDiagIs_02 = TTRUE;
+				else if(distSQ_13<distSQ_02)
+					bQuadDiagIs_02 = TFALSE;
+				else
+				{
+					const SVec3 P0 = GetPosition(pContext, i0);
+					const SVec3 P1 = GetPosition(pContext, i1);
+					const SVec3 P2 = GetPosition(pContext, i2);
+					const SVec3 P3 = GetPosition(pContext, i3);
+					const float distSQ_02 = LengthSquared(vsub(P2,P0));
+					const float distSQ_13 = LengthSquared(vsub(P3,P1));
+
+					bQuadDiagIs_02 = distSQ_13<distSQ_02 ? TFALSE : TTRUE;
+				}
+
+				if(bQuadDiagIs_02)
+				{
+					{
+						unsigned char * pVerts_A = pTriInfos[iDstTriIndex].vert_num;
+						pVerts_A[0]=0; pVerts_A[1]=1; pVerts_A[2]=2;
+					}
+					piTriList_out[iDstTriIndex*3+0] = i0;
+					piTriList_out[iDstTriIndex*3+1] = i1;
+					piTriList_out[iDstTriIndex*3+2] = i2;
+					++iDstTriIndex;	// next
+					{
+						unsigned char * pVerts_B = pTriInfos[iDstTriIndex].vert_num;
+						pVerts_B[0]=0; pVerts_B[1]=2; pVerts_B[2]=3;
+					}
+					piTriList_out[iDstTriIndex*3+0] = i0;
+					piTriList_out[iDstTriIndex*3+1] = i2;
+					piTriList_out[iDstTriIndex*3+2] = i3;
+					++iDstTriIndex;	// next
+				}
+				else
+				{
+					{
+						unsigned char * pVerts_A = pTriInfos[iDstTriIndex].vert_num;
+						pVerts_A[0]=0; pVerts_A[1]=1; pVerts_A[2]=3;
+					}
+					piTriList_out[iDstTriIndex*3+0] = i0;
+					piTriList_out[iDstTriIndex*3+1] = i1;
+					piTriList_out[iDstTriIndex*3+2] = i3;
+					++iDstTriIndex;	// next
+					{
+						unsigned char * pVerts_B = pTriInfos[iDstTriIndex].vert_num;
+						pVerts_B[0]=1; pVerts_B[1]=2; pVerts_B[2]=3;
+					}
+					piTriList_out[iDstTriIndex*3+0] = i1;
+					piTriList_out[iDstTriIndex*3+1] = i2;
+					piTriList_out[iDstTriIndex*3+2] = i3;
+					++iDstTriIndex;	// next
+				}
+			}
+		}
+
+		iTSpacesOffs += verts;
+		assert(iDstTriIndex<=iNrTrianglesIn);
+	}
+
+	for(t=0; t<iNrTrianglesIn; t++)
+		pTriInfos[t].iFlag = 0;
+
+	// return total amount of tspaces
+	return iTSpacesOffs;
+}
+
+const SVec3 GetPosition(const SMikkTSpaceContext * pContext, const int index)
+{
+	int iF, iI;
+	SVec3 res; float pos[3];
+	IndexToData(&iF, &iI, index);
+	pContext->m_pInterface->m_getPosition(pContext, pos, iF, iI);
+	res.x=pos[0]; res.y=pos[1]; res.z=pos[2];
+	return res;
+}
+
+const SVec3 GetNormal(const SMikkTSpaceContext * pContext, const int index)
+{
+	int iF, iI;
+	SVec3 res; float norm[3];
+	IndexToData(&iF, &iI, index);
+	pContext->m_pInterface->m_getNormal(pContext, norm, iF, iI);
+	res.x=norm[0]; res.y=norm[1]; res.z=norm[2];
+	return res;
+}
+
+const SVec3 GetTexCoord(const SMikkTSpaceContext * pContext, const int index)
+{
+	int iF, iI;
+	SVec3 res; float texc[2];
+	IndexToData(&iF, &iI, index);
+	pContext->m_pInterface->m_getTexCoord(pContext, texc, iF, iI);
+	res.x=texc[0]; res.y=texc[1]; res.z=1.0f;
+	return res;
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+
+typedef union
+{
+	struct
+	{
+		int i0, i1, f;
+	};
+	int array[3];
+} SEdge;
+
+void BuildNeighborsFast(STriInfo pTriInfos[], SEdge * pEdges, const int piTriListIn[], const int iNrTrianglesIn);
+void BuildNeighborsSlow(STriInfo pTriInfos[], const int piTriListIn[], const int iNrTrianglesIn);
+
+// returns the texture area times 2
+float CalcTexArea(const SMikkTSpaceContext * pContext, const int indices[])
+{
+	const SVec3 t1 = GetTexCoord(pContext, indices[0]);
+	const SVec3 t2 = GetTexCoord(pContext, indices[1]);
+	const SVec3 t3 = GetTexCoord(pContext, indices[2]);
+
+	const float t21x = t2.x-t1.x;
+	const float t21y = t2.y-t1.y;
+	const float t31x = t3.x-t1.x;
+	const float t31y = t3.y-t1.y;
+
+	const float fSignedAreaSTx2 = t21x*t31y - t21y*t31x;
+
+	return fSignedAreaSTx2<0 ? (-fSignedAreaSTx2) : fSignedAreaSTx2;
+}
+
+void InitTriInfo(STriInfo pTriInfos[], const int piTriListIn[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn)
+{
+	int f=0, i=0, t=0;
+	// pTriInfos[f].iFlag is cleared in GenerateInitialVerticesIndexList() which is called before this function.
+
+	// generate neighbor info list
+	for(f=0; f<iNrTrianglesIn; f++)
+		for(i=0; i<3; i++)
+		{
+			pTriInfos[f].FaceNeighbors[i] = -1;
+			pTriInfos[f].AssignedGroup[i] = NULL;
+
+			pTriInfos[f].vOs.x=0.0f; pTriInfos[f].vOs.y=0.0f; pTriInfos[f].vOs.z=0.0f;
+			pTriInfos[f].vOt.x=0.0f; pTriInfos[f].vOt.y=0.0f; pTriInfos[f].vOt.z=0.0f;
+			pTriInfos[f].fMagS = 0;
+			pTriInfos[f].fMagT = 0;
+
+			// assumed bad
+			pTriInfos[f].iFlag |= GROUP_WITH_ANY;
+		}
+
+	// evaluate first order derivatives
+	for(f=0; f<iNrTrianglesIn; f++)
+	{
+		// initial values
+		const SVec3 v1 = GetPosition(pContext, piTriListIn[f*3+0]);
+		const SVec3 v2 = GetPosition(pContext, piTriListIn[f*3+1]);
+		const SVec3 v3 = GetPosition(pContext, piTriListIn[f*3+2]);
+		const SVec3 t1 = GetTexCoord(pContext, piTriListIn[f*3+0]);
+		const SVec3 t2 = GetTexCoord(pContext, piTriListIn[f*3+1]);
+		const SVec3 t3 = GetTexCoord(pContext, piTriListIn[f*3+2]);
+
+		const float t21x = t2.x-t1.x;
+		const float t21y = t2.y-t1.y;
+		const float t31x = t3.x-t1.x;
+		const float t31y = t3.y-t1.y;
+		const SVec3 d1 = vsub(v2,v1);
+		const SVec3 d2 = vsub(v3,v1);
+
+		const float fSignedAreaSTx2 = t21x*t31y - t21y*t31x;
+		//assert(fSignedAreaSTx2!=0);
+		SVec3 vOs = vsub(vscale(t31y,d1), vscale(t21y,d2));	// eq 18
+		SVec3 vOt = vadd(vscale(-t31x,d1), vscale(t21x,d2)); // eq 19
+
+		pTriInfos[f].iFlag |= (fSignedAreaSTx2>0 ? ORIENT_PRESERVING : 0);
+
+		if( NotZero(fSignedAreaSTx2) )
+		{
+			const float fAbsArea = fabsf(fSignedAreaSTx2);
+			const float fLenOs = Length(vOs);
+			const float fLenOt = Length(vOt);
+			const float fS = (pTriInfos[f].iFlag&ORIENT_PRESERVING)==0 ? (-1.0f) : 1.0f;
+			if( NotZero(fLenOs) ) pTriInfos[f].vOs = vscale(fS/fLenOs, vOs);
+			if( NotZero(fLenOt) ) pTriInfos[f].vOt = vscale(fS/fLenOt, vOt);
+
+			// evaluate magnitudes prior to normalization of vOs and vOt
+			pTriInfos[f].fMagS = fLenOs / fAbsArea;
+			pTriInfos[f].fMagT = fLenOt / fAbsArea;
+
+			// if this is a good triangle
+			if( NotZero(pTriInfos[f].fMagS) && NotZero(pTriInfos[f].fMagT))
+				pTriInfos[f].iFlag &= (~GROUP_WITH_ANY);
+		}
+	}
+
+	// force otherwise healthy quads to a fixed orientation
+	while(t<(iNrTrianglesIn-1))
+	{
+		const int iFO_a = pTriInfos[t].iOrgFaceNumber;
+		const int iFO_b = pTriInfos[t+1].iOrgFaceNumber;
+		if(iFO_a==iFO_b)	// this is a quad
+		{
+			const tbool bIsDeg_a = (pTriInfos[t].iFlag&MARK_DEGENERATE)!=0 ? TTRUE : TFALSE;
+			const tbool bIsDeg_b = (pTriInfos[t+1].iFlag&MARK_DEGENERATE)!=0 ? TTRUE : TFALSE;
+			
+			// bad triangles should already have been removed by
+			// DegenPrologue(), but just in case check bIsDeg_a and bIsDeg_a are false
+			if((bIsDeg_a||bIsDeg_b)==TFALSE)
+			{
+				const tbool bOrientA = (pTriInfos[t].iFlag&ORIENT_PRESERVING)!=0 ? TTRUE : TFALSE;
+				const tbool bOrientB = (pTriInfos[t+1].iFlag&ORIENT_PRESERVING)!=0 ? TTRUE : TFALSE;
+				// if this happens the quad has extremely bad mapping!!
+				if(bOrientA!=bOrientB)
+				{
+					//printf("found quad with bad mapping\n");
+					tbool bChooseOrientFirstTri = TFALSE;
+					if((pTriInfos[t+1].iFlag&GROUP_WITH_ANY)!=0) bChooseOrientFirstTri = TTRUE;
+					else if( CalcTexArea(pContext, &piTriListIn[t*3+0]) >= CalcTexArea(pContext, &piTriListIn[(t+1)*3+0]) )
+						bChooseOrientFirstTri = TTRUE;
+
+					// force match
+					{
+						const int t0 = bChooseOrientFirstTri ? t : (t+1);
+						const int t1 = bChooseOrientFirstTri ? (t+1) : t;
+						pTriInfos[t1].iFlag &= (~ORIENT_PRESERVING);	// clear first
+						pTriInfos[t1].iFlag |= (pTriInfos[t0].iFlag&ORIENT_PRESERVING);	// copy bit
+					}
+				}
+			}
+			t += 2;
+		}
+		else
+			++t;
+	}
+	
+	// match up edge pairs
+	{
+		SEdge * pEdges = (SEdge *) malloc(sizeof(SEdge)*iNrTrianglesIn*3);
+		if(pEdges==NULL)
+			BuildNeighborsSlow(pTriInfos, piTriListIn, iNrTrianglesIn);
+		else
+		{
+			BuildNeighborsFast(pTriInfos, pEdges, piTriListIn, iNrTrianglesIn);
+	
+			free(pEdges);
+		}
+	}
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+
+tbool AssignRecur(const int piTriListIn[], STriInfo psTriInfos[], const int iMyTriIndex, SGroup * pGroup);
+void AddTriToGroup(SGroup * pGroup, const int iTriIndex);
+
+int Build4RuleGroups(STriInfo pTriInfos[], SGroup pGroups[], int piGroupTrianglesBuffer[], const int piTriListIn[], const int iNrTrianglesIn)
+{
+	const int iNrMaxGroups = iNrTrianglesIn*3;
+	int iNrActiveGroups = 0;
+	int iOffset = 0, f=0, i=0;
+	for(f=0; f<iNrTrianglesIn; f++)
+	{
+		for(i=0; i<3; i++)
+		{
+			// if not assigned to a group
+			if((pTriInfos[f].iFlag&GROUP_WITH_ANY)==0 && pTriInfos[f].AssignedGroup[i]==NULL)
+			{
+				tbool bOrPre;
+				int neigh_indexL, neigh_indexR;
+				const int vert_index = piTriListIn[f*3+i];
+				assert(iNrActiveGroups<iNrMaxGroups);
+				pTriInfos[f].AssignedGroup[i] = &pGroups[iNrActiveGroups];
+				pTriInfos[f].AssignedGroup[i]->iVertexRepresentitive = vert_index;
+				pTriInfos[f].AssignedGroup[i]->bOrientPreservering = (pTriInfos[f].iFlag&ORIENT_PRESERVING)!=0;
+				pTriInfos[f].AssignedGroup[i]->iNrFaces = 0;
+				pTriInfos[f].AssignedGroup[i]->pFaceIndices = &piGroupTrianglesBuffer[iOffset];
+				++iNrActiveGroups;
+
+				AddTriToGroup(pTriInfos[f].AssignedGroup[i], f);
+				bOrPre = (pTriInfos[f].iFlag&ORIENT_PRESERVING)!=0 ? TTRUE : TFALSE;
+				neigh_indexL = pTriInfos[f].FaceNeighbors[i];
+				neigh_indexR = pTriInfos[f].FaceNeighbors[i>0?(i-1):2];
+				if(neigh_indexL>=0) // neighbor
+				{
+					const tbool bAnswer =
+						AssignRecur(piTriListIn, pTriInfos, neigh_indexL,
+									pTriInfos[f].AssignedGroup[i] );
+					
+					const tbool bOrPre2 = (pTriInfos[neigh_indexL].iFlag&ORIENT_PRESERVING)!=0 ? TTRUE : TFALSE;
+					const tbool bDiff = bOrPre!=bOrPre2 ? TTRUE : TFALSE;
+					assert(bAnswer || bDiff);
+				}
+				if(neigh_indexR>=0) // neighbor
+				{
+					const tbool bAnswer =
+						AssignRecur(piTriListIn, pTriInfos, neigh_indexR,
+									pTriInfos[f].AssignedGroup[i] );
+
+					const tbool bOrPre2 = (pTriInfos[neigh_indexR].iFlag&ORIENT_PRESERVING)!=0 ? TTRUE : TFALSE;
+					const tbool bDiff = bOrPre!=bOrPre2 ? TTRUE : TFALSE;
+					assert(bAnswer || bDiff);
+				}
+
+				// update offset
+				iOffset += pTriInfos[f].AssignedGroup[i]->iNrFaces;
+				// since the groups are disjoint a triangle can never
+				// belong to more than 3 groups. Subsequently something
+				// is completely screwed if this assertion ever hits.
+				assert(iOffset <= iNrMaxGroups);
+			}
+		}
+	}
+
+	return iNrActiveGroups;
+}
+
+void AddTriToGroup(SGroup * pGroup, const int iTriIndex)
+{
+	pGroup->pFaceIndices[pGroup->iNrFaces] = iTriIndex;
+	++pGroup->iNrFaces;
+}
+
+tbool AssignRecur(const int piTriListIn[], STriInfo psTriInfos[],
+				 const int iMyTriIndex, SGroup * pGroup)
+{
+	STriInfo * pMyTriInfo = &psTriInfos[iMyTriIndex];
+
+	// track down vertex
+	const int iVertRep = pGroup->iVertexRepresentitive;
+	const int * pVerts = &piTriListIn[3*iMyTriIndex+0];
+	int i=-1;
+	if(pVerts[0]==iVertRep) i=0;
+	else if(pVerts[1]==iVertRep) i=1;
+	else if(pVerts[2]==iVertRep) i=2;
+	assert(i>=0 && i<3);
+
+	// early out
+	if(pMyTriInfo->AssignedGroup[i] == pGroup) return TTRUE;
+	else if(pMyTriInfo->AssignedGroup[i]!=NULL) return TFALSE;
+	if((pMyTriInfo->iFlag&GROUP_WITH_ANY)!=0)
+	{
+		// first to group with a group-with-anything triangle
+		// determines it's orientation.
+		// This is the only existing order dependency in the code!!
+		if( pMyTriInfo->AssignedGroup[0] == NULL &&
+			pMyTriInfo->AssignedGroup[1] == NULL &&
+			pMyTriInfo->AssignedGroup[2] == NULL )
+		{
+			pMyTriInfo->iFlag &= (~ORIENT_PRESERVING);
+			pMyTriInfo->iFlag |= (pGroup->bOrientPreservering ? ORIENT_PRESERVING : 0);
+		}
+	}
+	{
+		const tbool bOrient = (pMyTriInfo->iFlag&ORIENT_PRESERVING)!=0 ? TTRUE : TFALSE;
+		if(bOrient != pGroup->bOrientPreservering) return TFALSE;
+	}
+
+	AddTriToGroup(pGroup, iMyTriIndex);
+	pMyTriInfo->AssignedGroup[i] = pGroup;
+
+	{
+		const int neigh_indexL = pMyTriInfo->FaceNeighbors[i];
+		const int neigh_indexR = pMyTriInfo->FaceNeighbors[i>0?(i-1):2];
+		if(neigh_indexL>=0)
+			AssignRecur(piTriListIn, psTriInfos, neigh_indexL, pGroup);
+		if(neigh_indexR>=0)
+			AssignRecur(piTriListIn, psTriInfos, neigh_indexR, pGroup);
+	}
+
+
+
+	return TTRUE;
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////////////////////////////////
+
+tbool CompareSubGroups(const SSubGroup * pg1, const SSubGroup * pg2);
+void QuickSort(int* pSortBuffer, int iLeft, int iRight, unsigned int uSeed);
+STSpace EvalTspace(int face_indices[], const int iFaces, const int piTriListIn[], const STriInfo pTriInfos[], const SMikkTSpaceContext * pContext, const int iVertexRepresentitive);
+
+tbool GenerateTSpaces(STSpace psTspace[], const STriInfo pTriInfos[], const SGroup pGroups[],
+					 const int iNrActiveGroups, const int piTriListIn[], const float fThresCos,
+					 const SMikkTSpaceContext * pContext)
+{
+	STSpace * pSubGroupTspace = NULL;
+	SSubGroup * pUniSubGroups = NULL;
+	int * pTmpMembers = NULL;
+	int iMaxNrFaces=0, iUniqueTspaces=0, g=0, i=0;
+	for(g=0; g<iNrActiveGroups; g++)
+		if(iMaxNrFaces < pGroups[g].iNrFaces)
+			iMaxNrFaces = pGroups[g].iNrFaces;
+
+	if(iMaxNrFaces == 0) return TTRUE;
+
+	// make initial allocations
+	pSubGroupTspace = (STSpace *) malloc(sizeof(STSpace)*iMaxNrFaces);
+	pUniSubGroups = (SSubGroup *) malloc(sizeof(SSubGroup)*iMaxNrFaces);
+	pTmpMembers = (int *) malloc(sizeof(int)*iMaxNrFaces);
+	if(pSubGroupTspace==NULL || pUniSubGroups==NULL || pTmpMembers==NULL)
+	{
+		if(pSubGroupTspace!=NULL) free(pSubGroupTspace);	
+		if(pUniSubGroups!=NULL) free(pUniSubGroups);	
+		if(pTmpMembers!=NULL) free(pTmpMembers);	
+		return TFALSE;
+	}
+
+
+	iUniqueTspaces = 0;
+	for(g=0; g<iNrActiveGroups; g++)
+	{
+		const SGroup * pGroup = &pGroups[g];
+		int iUniqueSubGroups = 0, s=0;
+
+		for(i=0; i<pGroup->iNrFaces; i++)	// triangles
+		{
+			const int f = pGroup->pFaceIndices[i];	// triangle number
+			int index=-1, iVertIndex=-1, iOF_1=-1, iMembers=0, j=0, l=0;
+			SSubGroup tmp_group;
+			tbool bFound;
+			SVec3 n, vOs, vOt;
+			if(pTriInfos[f].AssignedGroup[0]==pGroup) index=0;
+			else if(pTriInfos[f].AssignedGroup[1]==pGroup) index=1;
+			else if(pTriInfos[f].AssignedGroup[2]==pGroup) index=2;
+			assert(index>=0 && index<3);
+
+			iVertIndex = piTriListIn[f*3+index];
+			assert(iVertIndex==pGroup->iVertexRepresentitive);
+
+			// is normalized already
+			n = GetNormal(pContext, iVertIndex);
+			
+			// project
+			vOs = vsub(pTriInfos[f].vOs, vscale(vdot(n,pTriInfos[f].vOs), n));
+			vOt = vsub(pTriInfos[f].vOt, vscale(vdot(n,pTriInfos[f].vOt), n));
+			if( VNotZero(vOs) ) vOs = Normalize(vOs);
+			if( VNotZero(vOt) ) vOt = Normalize(vOt);
+
+			// original face number
+			iOF_1 = pTriInfos[f].iOrgFaceNumber;
+			
+			iMembers = 0;
+			for(j=0; j<pGroup->iNrFaces; j++)
+			{
+				const int t = pGroup->pFaceIndices[j];	// triangle number
+				const int iOF_2 = pTriInfos[t].iOrgFaceNumber;
+
+				// project
+				SVec3 vOs2 = vsub(pTriInfos[t].vOs, vscale(vdot(n,pTriInfos[t].vOs), n));
+				SVec3 vOt2 = vsub(pTriInfos[t].vOt, vscale(vdot(n,pTriInfos[t].vOt), n));
+				if( VNotZero(vOs2) ) vOs2 = Normalize(vOs2);
+				if( VNotZero(vOt2) ) vOt2 = Normalize(vOt2);
+
+				{
+					const tbool bAny = ( (pTriInfos[f].iFlag | pTriInfos[t].iFlag) & GROUP_WITH_ANY )!=0 ? TTRUE : TFALSE;
+					// make sure triangles which belong to the same quad are joined.
+					const tbool bSameOrgFace = iOF_1==iOF_2 ? TTRUE : TFALSE;
+
+					const float fCosS = vdot(vOs,vOs2);
+					const float fCosT = vdot(vOt,vOt2);
+
+					assert(f!=t || bSameOrgFace);	// sanity check
+					if(bAny || bSameOrgFace || (fCosS>fThresCos && fCosT>fThresCos))
+						pTmpMembers[iMembers++] = t;
+				}
+			}
+
+			// sort pTmpMembers
+			tmp_group.iNrFaces = iMembers;
+			tmp_group.pTriMembers = pTmpMembers;
+			if(iMembers>1)
+			{
+				unsigned int uSeed = INTERNAL_RND_SORT_SEED;	// could replace with a random seed?
+				QuickSort(pTmpMembers, 0, iMembers-1, uSeed);
+			}
+
+			// look for an existing match
+			bFound = TFALSE;
+			l=0;
+			while(l<iUniqueSubGroups && !bFound)
+			{
+				bFound = CompareSubGroups(&tmp_group, &pUniSubGroups[l]);
+				if(!bFound) ++l;
+			}
+			
+			// assign tangent space index
+			assert(bFound || l==iUniqueSubGroups);
+			//piTempTangIndices[f*3+index] = iUniqueTspaces+l;
+
+			// if no match was found we allocate a new subgroup
+			if(!bFound)
+			{
+				// insert new subgroup
+				int * pIndices = (int *) malloc(sizeof(int)*iMembers);
+				if(pIndices==NULL)
+				{
+					// clean up and return false
+					int s=0;
+					for(s=0; s<iUniqueSubGroups; s++)
+						free(pUniSubGroups[s].pTriMembers);
+					free(pUniSubGroups);
+					free(pTmpMembers);
+					free(pSubGroupTspace);
+					return TFALSE;
+				}
+				pUniSubGroups[iUniqueSubGroups].iNrFaces = iMembers;
+				pUniSubGroups[iUniqueSubGroups].pTriMembers = pIndices;
+				memcpy(pIndices, tmp_group.pTriMembers, iMembers*sizeof(int));
+				pSubGroupTspace[iUniqueSubGroups] =
+					EvalTspace(tmp_group.pTriMembers, iMembers, piTriListIn, pTriInfos, pContext, pGroup->iVertexRepresentitive);
+				++iUniqueSubGroups;
+			}
+
+			// output tspace
+			{
+				const int iOffs = pTriInfos[f].iTSpacesOffs;
+				const int iVert = pTriInfos[f].vert_num[index];
+				STSpace * pTS_out = &psTspace[iOffs+iVert];
+				assert(pTS_out->iCounter<2);
+				assert(((pTriInfos[f].iFlag&ORIENT_PRESERVING)!=0) == pGroup->bOrientPreservering);
+				if(pTS_out->iCounter==1)
+				{
+					*pTS_out = AvgTSpace(pTS_out, &pSubGroupTspace[l]);
+					pTS_out->iCounter = 2;	// update counter
+					pTS_out->bOrient = pGroup->bOrientPreservering;
+				}
+				else
+				{
+					assert(pTS_out->iCounter==0);
+					*pTS_out = pSubGroupTspace[l];
+					pTS_out->iCounter = 1;	// update counter
+					pTS_out->bOrient = pGroup->bOrientPreservering;
+				}
+			}
+		}
+
+		// clean up and offset iUniqueTspaces
+		for(s=0; s<iUniqueSubGroups; s++)
+			free(pUniSubGroups[s].pTriMembers);
+		iUniqueTspaces += iUniqueSubGroups;
+		iUniqueSubGroups = 0;
+	}
+
+	// clean up
+	free(pUniSubGroups);
+	free(pTmpMembers);
+	free(pSubGroupTspace);
+
+	return TTRUE;
+}
+
+STSpace EvalTspace(int face_indices[], const int iFaces, const int piTriListIn[], const STriInfo pTriInfos[],
+				   const SMikkTSpaceContext * pContext, const int iVertexRepresentitive)
+{
+	STSpace res;
+	float fAngleSum = 0;
+	int face=0;
+	res.vOs.x=0.0f; res.vOs.y=0.0f; res.vOs.z=0.0f;
+	res.vOt.x=0.0f; res.vOt.y=0.0f; res.vOt.z=0.0f;
+	res.fMagS = 0; res.fMagT = 0;
+
+	for(face=0; face<iFaces; face++)
+	{
+		const int f = face_indices[face];
+
+		// only valid triangles get to add their contribution
+		if( (pTriInfos[f].iFlag&GROUP_WITH_ANY)==0 )
+		{
+			SVec3 n, vOs, vOt, p0, p1, p2, v1, v2;
+			float fCos, fAngle, fMagS, fMagT;
+			int i=-1, index=-1, i0=-1, i1=-1, i2=-1;
+			if(piTriListIn[3*f+0]==iVertexRepresentitive) i=0;
+			else if(piTriListIn[3*f+1]==iVertexRepresentitive) i=1;
+			else if(piTriListIn[3*f+2]==iVertexRepresentitive) i=2;
+			assert(i>=0 && i<3);
+
+			// project
+			index = piTriListIn[3*f+i];
+			n = GetNormal(pContext, index);
+			vOs = vsub(pTriInfos[f].vOs, vscale(vdot(n,pTriInfos[f].vOs), n));
+			vOt = vsub(pTriInfos[f].vOt, vscale(vdot(n,pTriInfos[f].vOt), n));
+			if( VNotZero(vOs) ) vOs = Normalize(vOs);
+			if( VNotZero(vOt) ) vOt = Normalize(vOt);
+
+			i2 = piTriListIn[3*f + (i<2?(i+1):0)];
+			i1 = piTriListIn[3*f + i];
+			i0 = piTriListIn[3*f + (i>0?(i-1):2)];
+
+			p0 = GetPosition(pContext, i0);
+			p1 = GetPosition(pContext, i1);
+			p2 = GetPosition(pContext, i2);
+			v1 = vsub(p0,p1);
+			v2 = vsub(p2,p1);
+
+			// project
+			v1 = vsub(v1, vscale(vdot(n,v1),n)); if( VNotZero(v1) ) v1 = Normalize(v1);
+			v2 = vsub(v2, vscale(vdot(n,v2),n)); if( VNotZero(v2) ) v2 = Normalize(v2);
+
+			// weight contribution by the angle
+			// between the two edge vectors
+			fCos = vdot(v1,v2); fCos=fCos>1?1:(fCos<(-1) ? (-1) : fCos);
+			fAngle = (const float) acos(fCos);
+			fMagS = pTriInfos[f].fMagS;
+			fMagT = pTriInfos[f].fMagT;
+
+			res.vOs=vadd(res.vOs, vscale(fAngle,vOs));
+			res.vOt=vadd(res.vOt,vscale(fAngle,vOt));
+			res.fMagS+=(fAngle*fMagS);
+			res.fMagT+=(fAngle*fMagT);
+			fAngleSum += fAngle;
+		}
+	}
+
+	// normalize
+	if( VNotZero(res.vOs) ) res.vOs = Normalize(res.vOs);
+	if( VNotZero(res.vOt) ) res.vOt = Normalize(res.vOt);
+	if(fAngleSum>0)
+	{
+		res.fMagS /= fAngleSum;
+		res.fMagT /= fAngleSum;
+	}
+
+	return res;
+}
+
+tbool CompareSubGroups(const SSubGroup * pg1, const SSubGroup * pg2)
+{
+	tbool bStillSame=TTRUE;
+	int i=0;
+	if(pg1->iNrFaces!=pg2->iNrFaces) return TFALSE;
+	while(i<pg1->iNrFaces && bStillSame)
+	{
+		bStillSame = pg1->pTriMembers[i]==pg2->pTriMembers[i] ? TTRUE : TFALSE;
+		if(bStillSame) ++i;
+	}
+	return bStillSame;
+}
+
+void QuickSort(int* pSortBuffer, int iLeft, int iRight, unsigned int uSeed)
+{
+	int iL, iR, n, index, iMid, iTmp;
+
+	// Random
+	unsigned int t=uSeed&31;
+	t=(uSeed<<t)|(uSeed>>(32-t));
+	uSeed=uSeed+t+3;
+	// Random end
+
+	iL=iLeft; iR=iRight;
+	n = (iR-iL)+1;
+	assert(n>=0);
+	index = (int) (uSeed%n);
+
+	iMid=pSortBuffer[index + iL];
+	iTmp;
+
+	do
+	{
+		while(pSortBuffer[iL] < iMid)
+			++iL;
+		while(pSortBuffer[iR] > iMid)
+			--iR;
+
+		if(iL <= iR)
+		{
+			iTmp = pSortBuffer[iL];
+			pSortBuffer[iL] = pSortBuffer[iR];
+			pSortBuffer[iR] = iTmp;
+			++iL; --iR;
+		}
+	}
+	while(iL <= iR);
+
+	if(iLeft < iR)
+		QuickSort(pSortBuffer, iLeft, iR, uSeed);
+	if(iL < iRight)
+		QuickSort(pSortBuffer, iL, iRight, uSeed);
+}
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+/////////////////////////////////////////////////////////////////////////////////////////////
+
+void QuickSortEdges(SEdge * pSortBuffer, int iLeft, int iRight, const int channel, unsigned int uSeed);
+void GetEdge(int * i0_out, int * i1_out, int * edgenum_out, const int indices[], const int i0_in, const int i1_in);
+
+void BuildNeighborsFast(STriInfo pTriInfos[], SEdge * pEdges, const int piTriListIn[], const int iNrTrianglesIn)
+{
+	// build array of edges
+	unsigned int uSeed = INTERNAL_RND_SORT_SEED;				// could replace with a random seed?
+	int iEntries=0, iCurStartIndex=-1, f=0, i=0;
+	for(f=0; f<iNrTrianglesIn; f++)
+		for(i=0; i<3; i++)
+		{
+			const int i0 = piTriListIn[f*3+i];
+			const int i1 = piTriListIn[f*3+(i<2?(i+1):0)];
+			pEdges[f*3+i].i0 = i0 < i1 ? i0 : i1;			// put minimum index in i0
+			pEdges[f*3+i].i1 = !(i0 < i1) ? i0 : i1;		// put maximum index in i1
+			pEdges[f*3+i].f = f;							// record face number
+		}
+
+	// sort over all edges by i0, this is the pricy one.
+	QuickSortEdges(pEdges, 0, iNrTrianglesIn*3-1, 0, uSeed);	// sort channel 0 which is i0
+
+	// sub sort over i1, should be fast.
+	// could replace this with a 64 bit int sort over (i0,i1)
+	// with i0 as msb in the quicksort call above.
+	iEntries = iNrTrianglesIn*3;
+	iCurStartIndex = 0;
+	for(i=1; i<iEntries; i++)
+	{
+		if(pEdges[iCurStartIndex].i0 != pEdges[i].i0)
+		{
+			const int iL = iCurStartIndex;
+			const int iR = i-1;
+			//const int iElems = i-iL;
+			iCurStartIndex = i;
+			QuickSortEdges(pEdges, iL, iR, 1, uSeed);	// sort channel 1 which is i1
+		}
+	}
+
+	// sub sort over f, which should be fast.
+	// this step is to remain compliant with BuildNeighborsSlow() when
+	// more than 2 triangles use the same edge (such as a butterfly topology).
+	iCurStartIndex = 0;
+	for(i=1; i<iEntries; i++)
+	{
+		if(pEdges[iCurStartIndex].i0 != pEdges[i].i0 || pEdges[iCurStartIndex].i1 != pEdges[i].i1)
+		{
+			const int iL = iCurStartIndex;
+			const int iR = i-1;
+			//const int iElems = i-iL;
+			iCurStartIndex = i;
+			QuickSortEdges(pEdges, iL, iR, 2, uSeed);	// sort channel 2 which is f
+		}
+	}
+
+	// pair up, adjacent triangles
+	for(i=0; i<iEntries; i++)
+	{
+		const int i0=pEdges[i].i0;
+		const int i1=pEdges[i].i1;
+		const int f = pEdges[i].f;
+		tbool bUnassigned_A;
+
+		int i0_A, i1_A;
+		int edgenum_A, edgenum_B=0;	// 0,1 or 2
+		GetEdge(&i0_A, &i1_A, &edgenum_A, &piTriListIn[f*3], i0, i1);	// resolve index ordering and edge_num
+		bUnassigned_A = pTriInfos[f].FaceNeighbors[edgenum_A] == -1 ? TTRUE : TFALSE;
+
+		if(bUnassigned_A)
+		{
+			// get true index ordering
+			int j=i+1, t;
+			tbool bNotFound = TTRUE;
+			while(j<iEntries && i0==pEdges[j].i0 && i1==pEdges[j].i1 && bNotFound)
+			{
+				tbool bUnassigned_B;
+				int i0_B, i1_B;
+				t = pEdges[j].f;
+				// flip i0_B and i1_B
+				GetEdge(&i1_B, &i0_B, &edgenum_B, &piTriListIn[t*3], pEdges[j].i0, pEdges[j].i1);	// resolve index ordering and edge_num
+				//assert(!(i0_A==i1_B && i1_A==i0_B));
+				bUnassigned_B =  pTriInfos[t].FaceNeighbors[edgenum_B]==-1 ? TTRUE : TFALSE;
+				if(i0_A==i0_B && i1_A==i1_B && bUnassigned_B)
+					bNotFound = TFALSE;
+				else
+					++j;
+			}
+
+			if(!bNotFound)
+			{
+				int t = pEdges[j].f;
+				pTriInfos[f].FaceNeighbors[edgenum_A] = t;
+				//assert(pTriInfos[t].FaceNeighbors[edgenum_B]==-1);
+				pTriInfos[t].FaceNeighbors[edgenum_B] = f;
+			}
+		}
+	}
+}
+
+void BuildNeighborsSlow(STriInfo pTriInfos[], const int piTriListIn[], const int iNrTrianglesIn)
+{
+	int f=0, i=0;
+	for(f=0; f<iNrTrianglesIn; f++)
+	{
+		for(i=0; i<3; i++)
+		{
+			// if unassigned
+			if(pTriInfos[f].FaceNeighbors[i] == -1)
+			{
+				const int i0_A = piTriListIn[f*3+i];
+				const int i1_A = piTriListIn[f*3+(i<2?(i+1):0)];
+
+				// search for a neighbor
+				tbool bFound = TFALSE;
+				int t=0, j=0;
+				while(!bFound && t<iNrTrianglesIn)
+				{
+					if(t!=f)
+					{
+						j=0;
+						while(!bFound && j<3)
+						{
+							// in rev order
+							const int i1_B = piTriListIn[t*3+j];
+							const int i0_B = piTriListIn[t*3+(j<2?(j+1):0)];
+							//assert(!(i0_A==i1_B && i1_A==i0_B));
+							if(i0_A==i0_B && i1_A==i1_B)
+								bFound = TTRUE;
+							else
+								++j;
+						}
+					}
+					
+					if(!bFound) ++t;
+				}
+
+				// assign neighbors
+				if(bFound)
+				{
+					pTriInfos[f].FaceNeighbors[i] = t;
+					//assert(pTriInfos[t].FaceNeighbors[j]==-1);
+					pTriInfos[t].FaceNeighbors[j] = f;
+				}
+			}
+		}
+	}
+}
+
+void QuickSortEdges(SEdge * pSortBuffer, int iLeft, int iRight, const int channel, unsigned int uSeed)
+{
+	unsigned int t;
+	int iL, iR, n, index, iMid;
+
+	// early out
+	SEdge sTmp;
+	const int iElems = iRight-iLeft+1;
+	if(iElems<2) return;
+	else if(iElems==2)
+	{
+		if(pSortBuffer[iLeft].array[channel] > pSortBuffer[iRight].array[channel])
+		{
+			sTmp = pSortBuffer[iLeft];
+			pSortBuffer[iLeft] = pSortBuffer[iRight];
+			pSortBuffer[iRight] = sTmp;
+		}
+		return;
+	}
+
+	// Random
+	t=uSeed&31;
+	t=(uSeed<<t)|(uSeed>>(32-t));
+	uSeed=uSeed+t+3;
+	// Random end
+
+	iL=iLeft, iR=iRight;
+	n = (iR-iL)+1;
+	assert(n>=0);
+	index = (int) (uSeed%n);
+
+	iMid=pSortBuffer[index + iL].array[channel];
+
+	do
+	{
+		while(pSortBuffer[iL].array[channel] < iMid)
+			++iL;
+		while(pSortBuffer[iR].array[channel] > iMid)
+			--iR;
+
+		if(iL <= iR)
+		{
+			sTmp = pSortBuffer[iL];
+			pSortBuffer[iL] = pSortBuffer[iR];
+			pSortBuffer[iR] = sTmp;
+			++iL; --iR;
+		}
+	}
+	while(iL <= iR);
+
+	if(iLeft < iR)
+		QuickSortEdges(pSortBuffer, iLeft, iR, channel, uSeed);
+	if(iL < iRight)
+		QuickSortEdges(pSortBuffer, iL, iRight, channel, uSeed);
+}
+
+// resolve ordering and edge number
+void GetEdge(int * i0_out, int * i1_out, int * edgenum_out, const int indices[], const int i0_in, const int i1_in)
+{
+	*edgenum_out = -1;
+	
+	// test if first index is on the edge
+	if(indices[0]==i0_in || indices[0]==i1_in)
+	{
+		// test if second index is on the edge
+		if(indices[1]==i0_in || indices[1]==i1_in)
+		{
+			edgenum_out[0]=0;	// first edge
+			i0_out[0]=indices[0];
+			i1_out[0]=indices[1];
+		}
+		else
+		{
+			edgenum_out[0]=2;	// third edge
+			i0_out[0]=indices[2];
+			i1_out[0]=indices[0];
+		}
+	}
+	else
+	{
+		// only second and third index is on the edge
+		edgenum_out[0]=1;	// second edge
+		i0_out[0]=indices[1];
+		i1_out[0]=indices[2];
+	}
+}
+
+
+/////////////////////////////////////////////////////////////////////////////////////////////
+/////////////////////////////////// Degenerate triangles ////////////////////////////////////
+
+void DegenPrologue(STriInfo pTriInfos[], int piTriList_out[], const int iNrTrianglesIn, const int iTotTris)
+{
+	int iNextGoodTriangleSearchIndex=-1;
+	tbool bStillFindingGoodOnes;
+
+	// locate quads with only one good triangle
+	int t=0;
+	while(t<(iTotTris-1))
+	{
+		const int iFO_a = pTriInfos[t].iOrgFaceNumber;
+		const int iFO_b = pTriInfos[t+1].iOrgFaceNumber;
+		if(iFO_a==iFO_b)	// this is a quad
+		{
+			const tbool bIsDeg_a = (pTriInfos[t].iFlag&MARK_DEGENERATE)!=0 ? TTRUE : TFALSE;
+			const tbool bIsDeg_b = (pTriInfos[t+1].iFlag&MARK_DEGENERATE)!=0 ? TTRUE : TFALSE;
+			if((bIsDeg_a^bIsDeg_b)!=0)
+			{
+				pTriInfos[t].iFlag |= QUAD_ONE_DEGEN_TRI;
+				pTriInfos[t+1].iFlag |= QUAD_ONE_DEGEN_TRI;
+			}
+			t += 2;
+		}
+		else
+			++t;
+	}
+
+	// reorder list so all degen triangles are moved to the back
+	// without reordering the good triangles
+	iNextGoodTriangleSearchIndex = 1;
+	t=0;
+	bStillFindingGoodOnes = TTRUE;
+	while(t<iNrTrianglesIn && bStillFindingGoodOnes)
+	{
+		const tbool bIsGood = (pTriInfos[t].iFlag&MARK_DEGENERATE)==0 ? TTRUE : TFALSE;
+		if(bIsGood)
+		{
+			if(iNextGoodTriangleSearchIndex < (t+2))
+				iNextGoodTriangleSearchIndex = t+2;
+		}
+		else
+		{
+			int t0, t1;
+			// search for the first good triangle.
+			tbool bJustADegenerate = TTRUE;
+			while(bJustADegenerate && iNextGoodTriangleSearchIndex<iTotTris)
+			{
+				const tbool bIsGood = (pTriInfos[iNextGoodTriangleSearchIndex].iFlag&MARK_DEGENERATE)==0 ? TTRUE : TFALSE;
+				if(bIsGood) bJustADegenerate=TFALSE;
+				else ++iNextGoodTriangleSearchIndex;
+			}
+
+			t0 = t;
+			t1 = iNextGoodTriangleSearchIndex;
+			++iNextGoodTriangleSearchIndex;
+			assert(iNextGoodTriangleSearchIndex > (t+1));
+
+			// swap triangle t0 and t1
+			if(!bJustADegenerate)
+			{
+				int i=0;
+				for(i=0; i<3; i++)
+				{
+					const int index = piTriList_out[t0*3+i];
+					piTriList_out[t0*3+i] = piTriList_out[t1*3+i];
+					piTriList_out[t1*3+i] = index;
+				}
+				{
+					const STriInfo tri_info = pTriInfos[t0];
+					pTriInfos[t0] = pTriInfos[t1];
+					pTriInfos[t1] = tri_info;
+				}
+			}
+			else
+				bStillFindingGoodOnes = TFALSE;	// this is not supposed to happen
+		}
+
+		if(bStillFindingGoodOnes) ++t;
+	}
+
+	assert(bStillFindingGoodOnes);	// code will still work.
+	assert(iNrTrianglesIn == t);
+}
+
+void DegenEpilogue(STSpace psTspace[], STriInfo pTriInfos[], int piTriListIn[], const SMikkTSpaceContext * pContext, const int iNrTrianglesIn, const int iTotTris)
+{
+	int t=0, i=0;
+	// deal with degenerate triangles
+	// punishment for degenerate triangles is O(N^2)
+	for(t=iNrTrianglesIn; t<iTotTris; t++)
+	{
+		// degenerate triangles on a quad with one good triangle are skipped
+		// here but processed in the next loop
+		const tbool bSkip = (pTriInfos[t].iFlag&QUAD_ONE_DEGEN_TRI)!=0 ? TTRUE : TFALSE;
+
+		if(!bSkip)
+		{
+			for(i=0; i<3; i++)
+			{
+				const int index1 = piTriListIn[t*3+i];
+				// search through the good triangles
+				tbool bNotFound = TTRUE;
+				int j=0;
+				while(bNotFound && j<(3*iNrTrianglesIn))
+				{
+					const int index2 = piTriListIn[j];
+					if(index1==index2) bNotFound=TFALSE;
+					else ++j;
+				}
+
+				if(!bNotFound)
+				{
+					const int iTri = j/3;
+					const int iVert = j%3;
+					const int iSrcVert=pTriInfos[iTri].vert_num[iVert];
+					const int iSrcOffs=pTriInfos[iTri].iTSpacesOffs;
+					const int iDstVert=pTriInfos[t].vert_num[i];
+					const int iDstOffs=pTriInfos[t].iTSpacesOffs;
+					
+					// copy tspace
+					psTspace[iDstOffs+iDstVert] = psTspace[iSrcOffs+iSrcVert];
+				}
+			}
+		}
+	}
+
+	// deal with degenerate quads with one good triangle
+	for(t=0; t<iNrTrianglesIn; t++)
+	{
+		// this triangle belongs to a quad where the
+		// other triangle is degenerate
+		if( (pTriInfos[t].iFlag&QUAD_ONE_DEGEN_TRI)!=0 )
+		{
+			SVec3 vDstP;
+			int iOrgF=-1, i=0;
+			tbool bNotFound;
+			unsigned char * pV = pTriInfos[t].vert_num;
+			int iFlag = (1<<pV[0]) | (1<<pV[1]) | (1<<pV[2]);
+			int iMissingIndex = 0;
+			if((iFlag&2)==0) iMissingIndex=1;
+			else if((iFlag&4)==0) iMissingIndex=2;
+			else if((iFlag&8)==0) iMissingIndex=3;
+
+			iOrgF = pTriInfos[t].iOrgFaceNumber;
+			vDstP = GetPosition(pContext, MakeIndex(iOrgF, iMissingIndex));
+			bNotFound = TTRUE;
+			i=0;
+			while(bNotFound && i<3)
+			{
+				const int iVert = pV[i];
+				const SVec3 vSrcP = GetPosition(pContext, MakeIndex(iOrgF, iVert));
+				if(veq(vSrcP, vDstP)==TTRUE)
+				{
+					const int iOffs = pTriInfos[t].iTSpacesOffs;
+					psTspace[iOffs+iMissingIndex] = psTspace[iOffs+iVert];
+					bNotFound=TFALSE;
+				}
+				else
+					++i;
+			}
+			assert(!bNotFound);
+		}
+	}
+}
diff --git a/source/blender/blenkernel/intern/subsurf_ccg.c b/source/blender/blenkernel/intern/subsurf_ccg.c
index a2d3016099d..0889f490e79 100644
--- a/source/blender/blenkernel/intern/subsurf_ccg.c
+++ b/source/blender/blenkernel/intern/subsurf_ccg.c
@@ -1392,7 +1392,7 @@ static void ccgDM_drawMappedFacesGLSL(DerivedMesh *dm, int (*setMaterial)(int, v
 	}																			\
 	if(attribs.tottang) {														\
 		float *tang = attribs.tang.array[a*4 + vert];							\
-		glVertexAttrib3fvARB(attribs.tang.glIndex, tang);						\
+		glVertexAttrib4fvARB(attribs.tang.glIndex, tang);						\
 	}																			\
 }
 
diff --git a/source/blender/blenkernel/mikktspace.h b/source/blender/blenkernel/mikktspace.h
new file mode 100644
index 00000000000..7775667b527
--- /dev/null
+++ b/source/blender/blenkernel/mikktspace.h
@@ -0,0 +1,143 @@
+/**
+ *  Copyright (C) 2011 by Morten S. Mikkelsen
+ *
+ *  This software is provided 'as-is', without any express or implied
+ *  warranty.  In no event will the authors be held liable for any damages
+ *  arising from the use of this software.
+ *
+ *  Permission is granted to anyone to use this software for any purpose,
+ *  including commercial applications, and to alter it and redistribute it
+ *  freely, subject to the following restrictions:
+ *
+ *  1. The origin of this software must not be misrepresented; you must not
+ *     claim that you wrote the original software. If you use this software
+ *     in a product, an acknowledgment in the product documentation would be
+ *     appreciated but is not required.
+ *  2. Altered source versions must be plainly marked as such, and must not be
+ *     misrepresented as being the original software.
+ *  3. This notice may not be removed or altered from any source distribution.
+ */
+
+#ifndef __MIKKTSPACE_H__
+#define __MIKKTSPACE_H__
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Author: Morten S. Mikkelsen
+ * Version: 1.0
+ *
+ * The files mikktspace.h and mikktspace.c are designed to be
+ * stand-alone files and it is important that they are kept this way.
+ * Not having dependencies on structures/classes/libraries specific
+ * to the program, in which they are used, allows them to be copied
+ * and used as is into any tool, program or plugin.
+ * The code is designed to consistently generate the same
+ * tangent spaces, for a given mesh, in any tool in which it is used.
+ * This is done by performing an internal welding step and subsequently an order-independent evaluation
+ * of tangent space for meshes consisting of triangles and quads.
+ * This means faces can be received in any order and the same is true for
+ * the order of vertices of each face. The generated result will not be affected
+ * by such reordering. Additionally, whether degenerate (vertices or texture coordinates)
+ * primitives are present or not will not affect the generated results either.
+ * Once tangent space calculation is done the vertices of degenerate primitives will simply
+ * inherit tangent space from neighboring non degenerate primitives.
+ * The analysis behind this implementation can be found in my master's thesis
+ * which is available for download --> http://image.diku.dk/projects/media/morten.mikkelsen.08.pdf
+ * Note that though the tangent spaces at the vertices are generated in an order-independent way,
+ * by this implementation, the interpolated tangent space is still affected by which diagonal is
+ * chosen to split each quad. A sensible solution is to have your tools pipeline always
+ * split quads by the shortest diagonal. This choice is order-independent and works with mirroring.
+ * If these have the same length then compare the diagonals defined by the texture coordinates.
+ * XNormal which is a tool for baking normal maps allows you to write your own tangent space plugin
+ * and also quad triangulator plugin.
+ */
+
+
+typedef int tbool;
+typedef struct SMikkTSpaceContext SMikkTSpaceContext;
+
+typedef struct
+{
+	// Returns the number of faces (triangles/quads) on the mesh to be processed.
+	int (*m_getNumFaces)(const SMikkTSpaceContext * pContext);
+
+	// Returns the number of vertices on face number iFace
+	// iFace is a number in the range {0, 1, ..., getNumFaces()-1}
+	int (*m_getNumVerticesOfFace)(const SMikkTSpaceContext * pContext, const int iFace);
+
+	// returns the position/normal/texcoord of the referenced face of vertex number iVert.
+	// iVert is in the range {0,1,2} for triangles and {0,1,2,3} for quads.
+	void (*m_getPosition)(const SMikkTSpaceContext * pContext, float fvPosOut[], const int iFace, const int iVert);
+	void (*m_getNormal)(const SMikkTSpaceContext * pContext, float fvNormOut[], const int iFace, const int iVert);
+	void (*m_getTexCoord)(const SMikkTSpaceContext * pContext, float fvTexcOut[], const int iFace, const int iVert);
+
+	// either (or both) of the two setTSpace callbacks can be set.
+	// The call-back m_setTSpaceBasic() is sufficient for basic normal mapping.
+
+	// This function is used to return the tangent and fSign to the application.
+	// fvTangent is a unit length vector.
+	// For normal maps it is sufficient to use the following simplified version of the bitangent which is generated at pixel/vertex level.
+	// bitangent = fSign * cross(vN, tangent);
+	// Note that the results are returned unindexed. It is possible to generate a new index list
+	// But averaging/overwriting tangent spaces by using an already existing index list WILL produce INCRORRECT results.
+	// DO NOT! use an already existing index list.
+	void (*m_setTSpaceBasic)(const SMikkTSpaceContext * pContext, const float fvTangent[], const float fSign, const int iFace, const int iVert);
+
+	// This function is used to return tangent space results to the application.
+	// fvTangent and fvBiTangent are unit length vectors and fMagS and fMagT are their
+	// true magnitudes which can be used for relief mapping effects.
+	// fvBiTangent is the "real" bitangent and thus may not be perpendicular to fvTangent.
+	// However, both are perpendicular to the vertex normal.
+	// For normal maps it is sufficient to use the following simplified version of the bitangent which is generated at pixel/vertex level.
+	// fSign = bIsOrientationPreserving ? 1.0f : (-1.0f);
+	// bitangent = fSign * cross(vN, tangent);
+	// Note that the results are returned unindexed. It is possible to generate a new index list
+	// But averaging/overwriting tangent spaces by using an already existing index list WILL produce INCRORRECT results.
+	// DO NOT! use an already existing index list.
+	void (*m_setTSpace)(const SMikkTSpaceContext * pContext, const float fvTangent[], const float fvBiTangent[], const float fMagS, const float fMagT,
+						const tbool bIsOrientationPreserving, const int iFace, const int iVert);
+} SMikkTSpaceInterface;
+
+struct SMikkTSpaceContext
+{
+	SMikkTSpaceInterface * m_pInterface;	// initialized with callback functions
+	void * m_pUserData;						// pointer to client side mesh data etc. (passed as the first parameter with every interface call)
+};
+
+// these are both thread safe!
+tbool genTangSpaceDefault(const SMikkTSpaceContext * pContext);	// Default (recommended) fAngularThreshold is 180 degrees (which means threshold disabled)
+tbool genTangSpace(const SMikkTSpaceContext * pContext, const float fAngularThreshold);
+
+
+// To avoid visual errors (distortions/unwanted hard edges in lighting), when using sampled normal maps, the
+// normal map sampler must use the exact inverse of the pixel shader transformation.
+// The most efficient transformation we can possibly do in the pixel shader is
+// achieved by using, directly, the "unnormalized" interpolated tangent, bitangent and vertex normal: vT, vB and vN.
+// pixel shader (fast transform out)
+// vNout = normalize( vNt.x * vT + vNt.y * vB + vNt.z * vN );
+// where vNt is the tangent space normal. The normal map sampler must likewise use the
+// interpolated and "unnormalized" tangent, bitangent and vertex normal to be compliant with the pixel shader.
+// sampler does (exact inverse of pixel shader):
+// float3 row0 = cross(vB, vN);
+// float3 row1 = cross(vN, vT);
+// float3 row2 = cross(vT, vB);
+// float fSign = dot(vT, row0)<0 ? -1 : 1;
+// vNt = normalize( fSign * float3(dot(vNout,row0), dot(vNout,row1), dot(vNout,row2)) );
+// where vNout is the sampled normal in some chosen 3D space.
+//
+// Should you choose to reconstruct the bitangent in the pixel shader instead
+// of the vertex shader, as explained earlier, then be sure to do this in the normal map sampler also.
+// Finally, beware of quad triangulations. If the normal map sampler doesn't use the same triangulation of
+// quads as your renderer then problems will occur since the interpolated tangent spaces will differ
+// eventhough the vertex level tangent spaces match. This can be solved either by triangulating before
+// sampling/exporting or by using the order-independent choice of diagonal for splitting quads suggested earlier.
+// However, this must be used both by the sampler and your tools/rendering pipeline.
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif