Fix T51561: Normal maps fail w/ quad + eevee

Generalize derived-mesh tangent calculation so
it can be used by Batch cache creation too.

11 files changed, 818 insertions, 635 deletions

diff --git a/source/blender/blenkernel/BKE_DerivedMesh.h b/source/blender/blenkernel/BKE_DerivedMesh.h
index c7bcf036f5b..1ac1fd10da6 100644
--- a/source/blender/blenkernel/BKE_DerivedMesh.h
+++ b/source/blender/blenkernel/BKE_DerivedMesh.h
@@ -785,17 +785,11 @@ void DM_draw_attrib_vertex_uniforms(const DMVertexAttribs *attribs);
 void DM_calc_tangents_names_from_gpu(
         const struct GPUVertexAttribs *gattribs,
         char (*tangent_names)[MAX_NAME], int *tangent_names_count);
-void DM_add_named_tangent_layer_for_uv(
-        CustomData *uv_data, CustomData *tan_data, int numLoopData,
-        const char *layer_name);
-void DM_calc_loop_tangents_step_0(
-        const CustomData *loopData, bool calc_active_tangent,
-        const char (*tangent_names)[MAX_NAME], int tangent_names_count,
-        bool *rcalc_act, bool *rcalc_ren, int *ract_uv_n, int *rren_uv_n,
-        char *ract_uv_name, char *rren_uv_name, char *rtangent_mask);
+
 void DM_calc_loop_tangents(
         DerivedMesh *dm, bool calc_active_tangent, const char (*tangent_names)[MAX_NAME],
         int tangent_names_count);
+
 void DM_calc_auto_bump_scale(DerivedMesh *dm);
 
 /** Set object's bounding box based on DerivedMesh min/max data */
diff --git a/source/blender/blenkernel/BKE_mesh.h b/source/blender/blenkernel/BKE_mesh.h
index e0f62cfd894..64f71f0ade5 100644
--- a/source/blender/blenkernel/BKE_mesh.h
+++ b/source/blender/blenkernel/BKE_mesh.h
@@ -186,13 +186,6 @@ void BKE_mesh_calc_normals_looptri(
         const struct MLoop *mloop,
         const struct MLoopTri *looptri, int looptri_num,
         float (*r_tri_nors)[3]);
-void BKE_mesh_loop_tangents_ex(
-        const struct MVert *mverts, const int numVerts, const struct MLoop *mloops,
-        float (*r_looptangent)[4], float (*loopnors)[3], const struct MLoopUV *loopuv,
-        const int numLoops, const struct MPoly *mpolys, const int numPolys,
-        struct ReportList *reports);
-void BKE_mesh_loop_tangents(
-        struct Mesh *mesh, const char *uvmap, float (*r_looptangents)[4], struct ReportList *reports);
 
 /**
  * References a contiguous loop-fan with normal offset vars.
diff --git a/source/blender/blenkernel/BKE_mesh_tangent.h b/source/blender/blenkernel/BKE_mesh_tangent.h
new file mode 100644
index 00000000000..66b8a26e35b
--- /dev/null
+++ b/source/blender/blenkernel/BKE_mesh_tangent.h
@@ -0,0 +1,59 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+#ifndef __BKE_MESH_TANGENT_H__
+#define __BKE_MESH_TANGENT_H__
+
+void BKE_mesh_calc_loop_tangent_single_ex(
+        const struct MVert *mverts, const int numVerts, const struct MLoop *mloops,
+        float (*r_looptangent)[4], float (*loopnors)[3], const struct MLoopUV *loopuv,
+        const int numLoops, const struct MPoly *mpolys, const int numPolys,
+        struct ReportList *reports);
+void BKE_mesh_calc_loop_tangent_single(
+        struct Mesh *mesh, const char *uvmap, float (*r_looptangents)[4], struct ReportList *reports);
+
+void BKE_mesh_calc_loop_tangent_ex(
+        const struct MVert *mvert,
+        const struct MPoly *mpoly, const uint mpoly_len,
+        const struct MLoop *mloop,
+        const struct MLoopTri *looptri, const uint looptri_len,
+
+        struct CustomData *loopdata,
+        bool calc_active_tangent,
+        const char (*tangent_names)[64], int tangent_names_len,
+        const float (*poly_normals)[3],
+        const float (*loop_normals)[3],
+        const float (*vert_orco)[3],
+        /* result */
+        struct CustomData *loopdata_out,
+        const uint  loopdata_out_len,
+        char *tangent_mask_curr_p);
+
+/* Helpers */
+void BKE_mesh_add_loop_tangent_named_layer_for_uv(
+        struct CustomData *uv_data, struct CustomData *tan_data, int numLoopData,
+        const char *layer_name);
+void BKE_mesh_calc_loop_tangent_step_0(
+        const struct CustomData *loopData, bool calc_active_tangent,
+        const char (*tangent_names)[64], int tangent_names_count,
+        bool *rcalc_act, bool *rcalc_ren, int *ract_uv_n, int *rren_uv_n,
+        char *ract_uv_name, char *rren_uv_name, char *rtangent_mask);
+
+#endif /* __BKE_MESH_TANGENT_H__ */
+
diff --git a/source/blender/blenkernel/CMakeLists.txt b/source/blender/blenkernel/CMakeLists.txt
index 1acc45c9f00..7af0b5d092a 100644
--- a/source/blender/blenkernel/CMakeLists.txt
+++ b/source/blender/blenkernel/CMakeLists.txt
@@ -136,6 +136,7 @@ set(SRC
 	intern/mesh_evaluate.c
 	intern/mesh_mapping.c
 	intern/mesh_remap.c
+	intern/mesh_tangent.c
 	intern/mesh_validate.c
 	intern/modifier.c
 	intern/modifiers_bmesh.c
@@ -263,6 +264,7 @@ set(SRC
 	BKE_mesh.h
 	BKE_mesh_mapping.h
 	BKE_mesh_remap.h
+	BKE_mesh_tangent.h
 	BKE_modifier.h
 	BKE_movieclip.h
 	BKE_multires.h
diff --git a/source/blender/blenkernel/intern/DerivedMesh.c b/source/blender/blenkernel/intern/DerivedMesh.c
index 150a919bf6b..a6b9a048763 100644
--- a/source/blender/blenkernel/intern/DerivedMesh.c
+++ b/source/blender/blenkernel/intern/DerivedMesh.c
@@ -60,6 +60,7 @@
 #include "BKE_modifier.h"
 #include "BKE_mesh.h"
 #include "BKE_mesh_mapping.h"
+#include "BKE_mesh_tangent.h"
 #include "BKE_object.h"
 #include "BKE_object_deform.h"
 #include "BKE_paint.h"
@@ -3038,234 +3039,6 @@ void mesh_get_mapped_verts_coords(DerivedMesh *dm, float (*r_cos)[3], const int
 
 /* ******************* GLSL ******************** */
 
-/** \name Tangent Space Calculation
- * \{ */
-
-/* Necessary complexity to handle looptri's as quads for correct tangents */
-#define USE_LOOPTRI_DETECT_QUADS
-
-typedef struct {
-	float (*precomputedFaceNormals)[3];
-	float (*precomputedLoopNormals)[3];
-	const MLoopTri *looptri;
-	MLoopUV *mloopuv;   /* texture coordinates */
-	MPoly *mpoly;       /* indices */
-	MLoop *mloop;       /* indices */
-	MVert *mvert;       /* vertices & normals */
-	float (*orco)[3];
-	float (*tangent)[4];    /* destination */
-	int numTessFaces;
-
-#ifdef USE_LOOPTRI_DETECT_QUADS
-	/* map from 'fake' face index to looptri,
-	 * quads will point to the first looptri of the quad */
-	const int    *face_as_quad_map;
-	int       num_face_as_quad_map;
-#endif
-
-} SGLSLMeshToTangent;
-
-/* interface */
-#include "mikktspace.h"
-
-static int dm_ts_GetNumFaces(const SMikkTSpaceContext *pContext)
-{
-	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
-
-#ifdef USE_LOOPTRI_DETECT_QUADS
-	return pMesh->num_face_as_quad_map;
-#else
-	return pMesh->numTessFaces;
-#endif
-}
-
-static int dm_ts_GetNumVertsOfFace(const SMikkTSpaceContext *pContext, const int face_num)
-{
-#ifdef USE_LOOPTRI_DETECT_QUADS
-	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
-	if (pMesh->face_as_quad_map) {
-		const MLoopTri *lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
-		const MPoly *mp = &pMesh->mpoly[lt->poly];
-		if (mp->totloop == 4) {
-			return 4;
-		}
-	}
-	return 3;
-#else
-	UNUSED_VARS(pContext, face_num);
-	return 3;
-#endif
-}
-
-static void dm_ts_GetPosition(
-        const SMikkTSpaceContext *pContext, float r_co[3],
-        const int face_num, const int vert_index)
-{
-	//assert(vert_index >= 0 && vert_index < 4);
-	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
-	const MLoopTri *lt;
-	int loop_index;
-	const float *co;
-
-#ifdef USE_LOOPTRI_DETECT_QUADS
-	if (pMesh->face_as_quad_map) {
-		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
-		const MPoly *mp = &pMesh->mpoly[lt->poly];
-		if (mp->totloop == 4) {
-			loop_index = mp->loopstart + vert_index;
-			goto finally;
-		}
-		/* fall through to regular triangle */
-	}
-	else {
-		lt = &pMesh->looptri[face_num];
-	}
-#else
-	lt = &pMesh->looptri[face_num];
-#endif
-	loop_index = lt->tri[vert_index];
-
-finally:
-	co = pMesh->mvert[pMesh->mloop[loop_index].v].co;
-	copy_v3_v3(r_co, co);
-}
-
-static void dm_ts_GetTextureCoordinate(
-        const SMikkTSpaceContext *pContext, float r_uv[2],
-        const int face_num, const int vert_index)
-{
-	//assert(vert_index >= 0 && vert_index < 4);
-	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
-	const MLoopTri *lt;
-	int loop_index;
-
-#ifdef USE_LOOPTRI_DETECT_QUADS
-	if (pMesh->face_as_quad_map) {
-		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
-		const MPoly *mp = &pMesh->mpoly[lt->poly];
-		if (mp->totloop == 4) {
-			loop_index = mp->loopstart + vert_index;
-			goto finally;
-		}
-		/* fall through to regular triangle */
-	}
-	else {
-		lt = &pMesh->looptri[face_num];
-	}
-#else
-	lt = &pMesh->looptri[face_num];
-#endif
-	loop_index = lt->tri[vert_index];
-
-finally:
-	if (pMesh->mloopuv != NULL) {
-		const float *uv = pMesh->mloopuv[loop_index].uv;
-		copy_v2_v2(r_uv, uv);
-	}
-	else {
-		const float *orco = pMesh->orco[pMesh->mloop[loop_index].v];
-		map_to_sphere(&r_uv[0], &r_uv[1], orco[0], orco[1], orco[2]);
-	}
-}
-
-static void dm_ts_GetNormal(
-        const SMikkTSpaceContext *pContext, float r_no[3],
-        const int face_num, const int vert_index)
-{
-	//assert(vert_index >= 0 && vert_index < 4);
-	SGLSLMeshToTangent *pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
-	const MLoopTri *lt;
-	int loop_index;
-
-#ifdef USE_LOOPTRI_DETECT_QUADS
-	if (pMesh->face_as_quad_map) {
-		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
-		const MPoly *mp = &pMesh->mpoly[lt->poly];
-		if (mp->totloop == 4) {
-			loop_index = mp->loopstart + vert_index;
-			goto finally;
-		}
-		/* fall through to regular triangle */
-	}
-	else {
-		lt = &pMesh->looptri[face_num];
-	}
-#else
-	lt = &pMesh->looptri[face_num];
-#endif
-	loop_index = lt->tri[vert_index];
-
-finally:
-	if (pMesh->precomputedLoopNormals) {
-		copy_v3_v3(r_no, pMesh->precomputedLoopNormals[loop_index]);
-	}
-	else if ((pMesh->mpoly[lt->poly].flag & ME_SMOOTH) == 0) {  /* flat */
-		if (pMesh->precomputedFaceNormals) {
-			copy_v3_v3(r_no, pMesh->precomputedFaceNormals[lt->poly]);
-		}
-		else {
-#ifdef USE_LOOPTRI_DETECT_QUADS
-			const MPoly *mp = &pMesh->mpoly[lt->poly];
-			if (mp->totloop == 4) {
-				normal_quad_v3(
-				        r_no,
-				        pMesh->mvert[pMesh->mloop[mp->loopstart + 0].v].co,
-				        pMesh->mvert[pMesh->mloop[mp->loopstart + 1].v].co,
-				        pMesh->mvert[pMesh->mloop[mp->loopstart + 2].v].co,
-				        pMesh->mvert[pMesh->mloop[mp->loopstart + 3].v].co);
-			}
-			else
-#endif
-			{
-				normal_tri_v3(
-				        r_no,
-				        pMesh->mvert[pMesh->mloop[lt->tri[0]].v].co,
-				        pMesh->mvert[pMesh->mloop[lt->tri[1]].v].co,
-				        pMesh->mvert[pMesh->mloop[lt->tri[2]].v].co);
-			}
-		}
-	}
-	else {
-		const short *no = pMesh->mvert[pMesh->mloop[loop_index].v].no;
-		normal_short_to_float_v3(r_no, no);
-	}
-}
-
-static void dm_ts_SetTSpace(
-        const SMikkTSpaceContext *pContext, const float fvTangent[3], const float fSign,
-        const int face_num, const int vert_index)
-{
-	//assert(vert_index >= 0 && vert_index < 4);
-	SGLSLMeshToTangent *pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
-	const MLoopTri *lt;
-	int loop_index;
-
-#ifdef USE_LOOPTRI_DETECT_QUADS
-	if (pMesh->face_as_quad_map) {
-		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
-		const MPoly *mp = &pMesh->mpoly[lt->poly];
-		if (mp->totloop == 4) {
-			loop_index = mp->loopstart + vert_index;
-			goto finally;
-		}
-		/* fall through to regular triangle */
-	}
-	else {
-		lt = &pMesh->looptri[face_num];
-	}
-#else
-	lt = &pMesh->looptri[face_num];
-#endif
-	loop_index = lt->tri[vert_index];
-
-	float *pRes;
-
-finally:
-	pRes = pMesh->tangent[loop_index];
-	copy_v3_v3(pRes, fvTangent);
-	pRes[3] = fSign;
-}
-
 void DM_calc_tangents_names_from_gpu(
         const GPUVertexAttribs *gattribs,
         char (*tangent_names)[MAX_NAME], int *r_tangent_names_count)
@@ -3279,240 +3052,29 @@ void DM_calc_tangents_names_from_gpu(
 	*r_tangent_names_count = count;
 }
 
-static void DM_calc_loop_tangents_thread(TaskPool * __restrict UNUSED(pool), void *taskdata, int UNUSED(threadid))
-{
-	struct SGLSLMeshToTangent *mesh2tangent = taskdata;
-	/* new computation method */
-	{
-		SMikkTSpaceContext sContext = {NULL};
-		SMikkTSpaceInterface sInterface = {NULL};
-
-		sContext.m_pUserData = mesh2tangent;
-		sContext.m_pInterface = &sInterface;
-		sInterface.m_getNumFaces = dm_ts_GetNumFaces;
-		sInterface.m_getNumVerticesOfFace = dm_ts_GetNumVertsOfFace;
-		sInterface.m_getPosition = dm_ts_GetPosition;
-		sInterface.m_getTexCoord = dm_ts_GetTextureCoordinate;
-		sInterface.m_getNormal = dm_ts_GetNormal;
-		sInterface.m_setTSpaceBasic = dm_ts_SetTSpace;
-
-		/* 0 if failed */
-		genTangSpaceDefault(&sContext);
-	}
-}
-
-void DM_add_named_tangent_layer_for_uv(
-        CustomData *uv_data, CustomData *tan_data, int numLoopData,
-        const char *layer_name)
-{
-	if (CustomData_get_named_layer_index(tan_data, CD_TANGENT, layer_name) == -1 &&
-	    CustomData_get_named_layer_index(uv_data, CD_MLOOPUV, layer_name) != -1)
-	{
-		CustomData_add_layer_named(
-		        tan_data, CD_TANGENT, CD_CALLOC, NULL,
-		        numLoopData, layer_name);
-	}
-}
-
-/**
- * Here we get some useful information such as active uv layer name and search if it is already in tangent_names.
- * Also, we calculate tangent_mask that works as a descriptor of tangents state.
- * If tangent_mask has changed, then recalculate tangents.
- */
-void DM_calc_loop_tangents_step_0(
-        const CustomData *loopData, bool calc_active_tangent,
-        const char (*tangent_names)[MAX_NAME], int tangent_names_count,
-        bool *rcalc_act, bool *rcalc_ren, int *ract_uv_n, int *rren_uv_n,
-        char *ract_uv_name, char *rren_uv_name, char *rtangent_mask) {
-	/* Active uv in viewport */
-	int layer_index = CustomData_get_layer_index(loopData, CD_MLOOPUV);
-	*ract_uv_n = CustomData_get_active_layer(loopData, CD_MLOOPUV);
-	ract_uv_name[0] = 0;
-	if (*ract_uv_n != -1) {
-		strcpy(ract_uv_name, loopData->layers[*ract_uv_n + layer_index].name);
-	}
-
-	/* Active tangent in render */
-	*rren_uv_n = CustomData_get_render_layer(loopData, CD_MLOOPUV);
-	rren_uv_name[0] = 0;
-	if (*rren_uv_n != -1) {
-		strcpy(rren_uv_name, loopData->layers[*rren_uv_n + layer_index].name);
-	}
-
-	/* If active tangent not in tangent_names we take it into account */
-	*rcalc_act = false;
-	*rcalc_ren = false;
-	for (int i = 0; i < tangent_names_count; i++) {
-		if (tangent_names[i][0] == 0) {
-			calc_active_tangent = true;
-		}
-	}
-	if (calc_active_tangent) {
-		*rcalc_act = true;
-		*rcalc_ren = true;
-		for (int i = 0; i < tangent_names_count; i++) {
-			if (STREQ(ract_uv_name, tangent_names[i]))
-				*rcalc_act = false;
-			if (STREQ(rren_uv_name, tangent_names[i]))
-				*rcalc_ren = false;
-		}
-	}
-	*rtangent_mask = 0;
-
-	const int uv_layer_num = CustomData_number_of_layers(loopData, CD_MLOOPUV);
-	for (int n = 0; n < uv_layer_num; n++) {
-		const char *name = CustomData_get_layer_name(loopData, CD_MLOOPUV, n);
-		bool add = false;
-		for (int i = 0; i < tangent_names_count; i++) {
-			if (tangent_names[i][0] && STREQ(tangent_names[i], name)) {
-				add = true;
-				break;
-			}
-		}
-		if ((*rcalc_act && ract_uv_name[0] && STREQ(ract_uv_name, name)) ||
-		    (*rcalc_ren && rren_uv_name[0] && STREQ(rren_uv_name, name)))
-		{
-			add = true;
-		}
-		if (add)
-			*rtangent_mask |= 1 << n;
-	}
-}
-
 void DM_calc_loop_tangents(
         DerivedMesh *dm, bool calc_active_tangent,
-        const char (*tangent_names)[MAX_NAME], int tangent_names_count)
+        const char (*tangent_names)[MAX_NAME], int tangent_names_len)
 {
-	if (CustomData_number_of_layers(&dm->loopData, CD_MLOOPUV) == 0)
+	if (CustomData_number_of_layers(&dm->loopData, CD_MLOOPUV) == 0) {
 		return;
-	int act_uv_n = -1;
-	int ren_uv_n = -1;
-	bool calc_act = false;
-	bool calc_ren = false;
-	char act_uv_name[MAX_NAME];
-	char ren_uv_name[MAX_NAME];
-	char tangent_mask = 0;
-	DM_calc_loop_tangents_step_0(
-	        &dm->loopData, calc_active_tangent, tangent_names, tangent_names_count,
-	        &calc_act, &calc_ren, &act_uv_n, &ren_uv_n, act_uv_name, ren_uv_name, &tangent_mask);
-	if ((dm->tangent_mask | tangent_mask) != dm->tangent_mask) {
-		/* Check we have all the needed layers */
-		MPoly *mpoly = dm->getPolyArray(dm);
-		const MLoopTri *looptri = dm->getLoopTriArray(dm);
-		int totface = dm->getNumLoopTri(dm);
-		/* Allocate needed tangent layers */
-		for (int i = 0; i < tangent_names_count; i++)
-			if (tangent_names[i][0])
-				DM_add_named_tangent_layer_for_uv(&dm->loopData, &dm->loopData, dm->numLoopData, tangent_names[i]);
-		if (calc_act && act_uv_name[0])
-			DM_add_named_tangent_layer_for_uv(&dm->loopData, &dm->loopData, dm->numLoopData, act_uv_name);
-		if (calc_ren && ren_uv_name[0])
-			DM_add_named_tangent_layer_for_uv(&dm->loopData, &dm->loopData, dm->numLoopData, ren_uv_name);
-
-#ifdef USE_LOOPTRI_DETECT_QUADS
-		int num_face_as_quad_map;
-		int *face_as_quad_map = NULL;
-
-		/* map faces to quads */
-		if (totface != dm->getNumPolys(dm)) {
-			/* over alloc, since we dont know how many ngon or quads we have */
-
-			/* map fake face index to looptri */
-			face_as_quad_map = MEM_mallocN(sizeof(int) * totface, __func__);
-			int k, j;
-			for (k = 0, j = 0; j < totface; k++, j++) {
-				face_as_quad_map[k] = j;
-				/* step over all quads */
-				if (mpoly[looptri[j].poly].totloop == 4) {
-					j++;  /* skips the nest looptri */
-				}
-			}
-			num_face_as_quad_map = k;
-		}
-		else {
-			num_face_as_quad_map = totface;
-		}
-#endif
-
-		/* Calculation */
-		{
-			TaskScheduler *scheduler = BLI_task_scheduler_get();
-			TaskPool *task_pool;
-			task_pool = BLI_task_pool_create(scheduler, NULL);
-
-			dm->tangent_mask = 0;
-			/* Calculate tangent layers */
-			SGLSLMeshToTangent data_array[MAX_MTFACE];
-			const int tangent_layer_num = CustomData_number_of_layers(&dm->loopData, CD_TANGENT);
-			for (int n = 0; n < tangent_layer_num; n++) {
-				int index = CustomData_get_layer_index_n(&dm->loopData, CD_TANGENT, n);
-				BLI_assert(n < MAX_MTFACE);
-				SGLSLMeshToTangent *mesh2tangent = &data_array[n];
-				mesh2tangent->numTessFaces = totface;
-#ifdef USE_LOOPTRI_DETECT_QUADS
-				mesh2tangent->face_as_quad_map = face_as_quad_map;
-				mesh2tangent->num_face_as_quad_map = num_face_as_quad_map;
-#endif
-				mesh2tangent->mvert = dm->getVertArray(dm);
-				mesh2tangent->mpoly = dm->getPolyArray(dm);
-				mesh2tangent->mloop = dm->getLoopArray(dm);
-				mesh2tangent->looptri = dm->getLoopTriArray(dm);
-				/* Note, we assume we do have tessellated loop normals at this point (in case it is object-enabled),
-				 * have to check this is valid...
-				 */
-				mesh2tangent->precomputedLoopNormals = dm->getLoopDataArray(dm, CD_NORMAL);
-				mesh2tangent->precomputedFaceNormals = CustomData_get_layer(&dm->polyData, CD_NORMAL);
-
-				mesh2tangent->orco = NULL;
-				mesh2tangent->mloopuv = CustomData_get_layer_named(&dm->loopData, CD_MLOOPUV, dm->loopData.layers[index].name);
-				if (!mesh2tangent->mloopuv) {
-					mesh2tangent->orco = dm->getVertDataArray(dm, CD_ORCO);
-					if (!mesh2tangent->orco)
-						continue;
-				}
-				mesh2tangent->tangent = dm->loopData.layers[index].data;
-
-				/* Fill the resulting tangent_mask */
-				int uv_ind = CustomData_get_named_layer_index(&dm->loopData, CD_MLOOPUV, dm->loopData.layers[index].name);
-				int uv_start = CustomData_get_layer_index(&dm->loopData, CD_MLOOPUV);
-				BLI_assert(uv_ind != -1 && uv_start != -1);
-				BLI_assert(uv_ind - uv_start < MAX_MTFACE);
-				dm->tangent_mask |= 1 << (uv_ind - uv_start);
-				BLI_task_pool_push(task_pool, DM_calc_loop_tangents_thread, mesh2tangent, false, TASK_PRIORITY_LOW);
-			}
-
-			BLI_assert(dm->tangent_mask == tangent_mask);
-			BLI_task_pool_work_and_wait(task_pool);
-			BLI_task_pool_free(task_pool);
-		}
-#ifdef USE_LOOPTRI_DETECT_QUADS
-		if (face_as_quad_map) {
-			MEM_freeN(face_as_quad_map);
-		}
-#undef USE_LOOPTRI_DETECT_QUADS
-
-#endif
-
-		int uv_index, tan_index;
-
-		/* Update active layer index */
-		uv_index = CustomData_get_layer_index_n(&dm->loopData, CD_MLOOPUV, act_uv_n);
-		if (uv_index != -1) {
-			tan_index = CustomData_get_named_layer_index(&dm->loopData, CD_TANGENT, dm->loopData.layers[uv_index].name);
-			CustomData_set_layer_active_index(&dm->loopData, CD_TANGENT, tan_index);
-		}
-
-		/* Update render layer index */
-		uv_index = CustomData_get_layer_index_n(&dm->loopData, CD_MLOOPUV, ren_uv_n);
-		if (uv_index != -1) {
-			tan_index = CustomData_get_named_layer_index(&dm->loopData, CD_TANGENT, dm->loopData.layers[uv_index].name);
-			CustomData_set_layer_render_index(&dm->loopData, CD_TANGENT, tan_index);
-		}
 	}
-}
-
-/** \} */
 
+	BKE_mesh_calc_loop_tangent_ex(
+	        dm->getVertArray(dm),
+	        dm->getPolyArray(dm), dm->getNumPolys(dm),
+	        dm->getLoopArray(dm),
+	        dm->getLoopTriArray(dm), dm->getNumLoopTri(dm),
+	        &dm->loopData,
+	        calc_active_tangent,
+	        tangent_names, tangent_names_len,
+	        CustomData_get_layer(&dm->polyData, CD_NORMAL),
+	        dm->getLoopDataArray(dm, CD_NORMAL),
+	        dm->getVertDataArray(dm, CD_ORCO),  /* may be NULL */
+	        /* result */
+	        &dm->loopData, dm->getNumLoops(dm),
+	        &dm->tangent_mask);
+}
 
 void DM_calc_auto_bump_scale(DerivedMesh *dm)
 {
diff --git a/source/blender/blenkernel/intern/editderivedmesh.c b/source/blender/blenkernel/intern/editderivedmesh.c
index 320299d1933..74cc260836a 100644
--- a/source/blender/blenkernel/intern/editderivedmesh.c
+++ b/source/blender/blenkernel/intern/editderivedmesh.c
@@ -245,6 +245,11 @@ static void emDM_calc_loop_tangents(
 {
 	EditDerivedBMesh *bmdm = (EditDerivedBMesh *)dm;
 	BMEditMesh *em = bmdm->em;
+
+	if (CustomData_number_of_layers(&em->bm->ldata, CD_MLOOPUV) == 0) {
+		return;
+	}
+
 	const float (*poly_normals)[3] = bmdm->polyNos;
 	const float (*loop_normals)[3] = CustomData_get_layer(&dm->loopData, CD_NORMAL);
 	const float (*vert_orco)[3] = dm->getVertDataArray(dm, CD_ORCO);  /* can be NULL */
diff --git a/source/blender/blenkernel/intern/editmesh_tangent.c b/source/blender/blenkernel/intern/editmesh_tangent.c
index 501ddb10d4f..b04fc753f7a 100644
--- a/source/blender/blenkernel/intern/editmesh_tangent.c
+++ b/source/blender/blenkernel/intern/editmesh_tangent.c
@@ -28,6 +28,7 @@
 #include "BKE_DerivedMesh.h"
 
 #include "BKE_mesh.h"
+#include "BKE_mesh_tangent.h"  /* for utility functions */
 #include "BKE_editmesh.h"
 #include "BKE_editmesh_tangent.h"
 
@@ -268,7 +269,7 @@ static void emDM_calc_loop_tangents_thread(TaskPool * __restrict UNUSED(pool), v
 }
 
 /**
- * \see #DM_calc_loop_tangents, same logic but used arrays instead of #BMesh data.
+ * \see #BKE_mesh_calc_loop_tangent, same logic but used arrays instead of #BMesh data.
  *
  * \note This function is not so normal, its using `bm->ldata` as input, but output's to `dm->loopData`.
  * This is done because #CD_TANGENT is cache data used only for drawing.
@@ -285,8 +286,8 @@ void BKE_editmesh_loop_tangent_calc(
         char *tangent_mask_curr_p)
 {
 	BMesh *bm = em->bm;
-	if (CustomData_number_of_layers(&bm->ldata, CD_MLOOPUV) == 0)
-		return;
+
+	BLI_assert(CustomData_number_of_layers(&bm->ldata, CD_MLOOPUV) != 0);
 
 	int act_uv_n = -1;
 	int ren_uv_n = -1;
@@ -297,18 +298,18 @@ void BKE_editmesh_loop_tangent_calc(
 	char tangent_mask = 0;
 	char tangent_mask_curr = *tangent_mask_curr_p;
 
-	DM_calc_loop_tangents_step_0(
+	BKE_mesh_calc_loop_tangent_step_0(
 	        &bm->ldata, calc_active_tangent, tangent_names, tangent_names_len,
 	        &calc_act, &calc_ren, &act_uv_n, &ren_uv_n, act_uv_name, ren_uv_name, &tangent_mask);
 
 	if ((tangent_mask_curr | tangent_mask) != tangent_mask_curr) {
 		for (int i = 0; i < tangent_names_len; i++)
 			if (tangent_names[i][0])
-				DM_add_named_tangent_layer_for_uv(&bm->ldata, loopdata_out, loopdata_out_len, tangent_names[i]);
+				BKE_mesh_add_loop_tangent_named_layer_for_uv(&bm->ldata, loopdata_out, loopdata_out_len, tangent_names[i]);
 		if (calc_act && act_uv_name[0])
-			DM_add_named_tangent_layer_for_uv(&bm->ldata, loopdata_out, loopdata_out_len, act_uv_name);
+			BKE_mesh_add_loop_tangent_named_layer_for_uv(&bm->ldata, loopdata_out, loopdata_out_len, act_uv_name);
 		if (calc_ren && ren_uv_name[0])
-			DM_add_named_tangent_layer_for_uv(&bm->ldata, loopdata_out, loopdata_out_len, ren_uv_name);
+			BKE_mesh_add_loop_tangent_named_layer_for_uv(&bm->ldata, loopdata_out, loopdata_out_len, ren_uv_name);
 		int totface = em->tottri;
 #ifdef USE_LOOPTRI_DETECT_QUADS
 		int num_face_as_quad_map;
diff --git a/source/blender/blenkernel/intern/mesh_evaluate.c b/source/blender/blenkernel/intern/mesh_evaluate.c
index 37f4477febf..7e3791acc26 100644
--- a/source/blender/blenkernel/intern/mesh_evaluate.c
+++ b/source/blender/blenkernel/intern/mesh_evaluate.c
@@ -1665,152 +1665,6 @@ void BKE_mesh_normals_loop_to_vertex(
 
 /* -------------------------------------------------------------------- */
 
-/** \name Mesh Tangent Calculations
- * \{ */
-
-/* Tangent space utils. */
-
-/* User data. */
-typedef struct {
-	const MPoly *mpolys;   /* faces */
-	const MLoop *mloops;   /* faces's vertices */
-	const MVert *mverts;   /* vertices */
-	const MLoopUV *luvs;   /* texture coordinates */
-	float (*lnors)[3];     /* loops' normals */
-	float (*tangents)[4];  /* output tangents */
-	int num_polys;         /* number of polygons */
-} BKEMeshToTangent;
-
-/* Mikktspace's API */
-static int get_num_faces(const SMikkTSpaceContext *pContext)
-{
-	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
-	return p_mesh->num_polys;
-}
-
-static int get_num_verts_of_face(const SMikkTSpaceContext *pContext, const int face_idx)
-{
-	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
-	return p_mesh->mpolys[face_idx].totloop;
-}
-
-static void get_position(const SMikkTSpaceContext *pContext, float r_co[3], const int face_idx, const int vert_idx)
-{
-	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
-	const int loop_idx = p_mesh->mpolys[face_idx].loopstart + vert_idx;
-	copy_v3_v3(r_co, p_mesh->mverts[p_mesh->mloops[loop_idx].v].co);
-}
-
-static void get_texture_coordinate(const SMikkTSpaceContext *pContext, float r_uv[2], const int face_idx,
-                                   const int vert_idx)
-{
-	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
-	copy_v2_v2(r_uv, p_mesh->luvs[p_mesh->mpolys[face_idx].loopstart + vert_idx].uv);
-}
-
-static void get_normal(const SMikkTSpaceContext *pContext, float r_no[3], const int face_idx, const int vert_idx)
-{
-	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
-	copy_v3_v3(r_no, p_mesh->lnors[p_mesh->mpolys[face_idx].loopstart + vert_idx]);
-}
-
-static void set_tspace(const SMikkTSpaceContext *pContext, const float fv_tangent[3], const float face_sign,
-                       const int face_idx, const int vert_idx)
-{
-	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
-	float *p_res = p_mesh->tangents[p_mesh->mpolys[face_idx].loopstart + vert_idx];
-	copy_v3_v3(p_res, fv_tangent);
-	p_res[3] = face_sign;
-}
-
-/**
- * Compute simplified tangent space normals, i.e. tangent vector + sign of bi-tangent one, which combined with
- * split normals can be used to recreate the full tangent space.
- * Note: * The mesh should be made of only tris and quads!
- */
-void BKE_mesh_loop_tangents_ex(
-        const MVert *mverts, const int UNUSED(numVerts), const MLoop *mloops,
-        float (*r_looptangent)[4], float (*loopnors)[3], const MLoopUV *loopuvs,
-        const int UNUSED(numLoops), const MPoly *mpolys, const int numPolys,
-        ReportList *reports)
-{
-	BKEMeshToTangent mesh_to_tangent = {NULL};
-	SMikkTSpaceContext s_context = {NULL};
-	SMikkTSpaceInterface s_interface = {NULL};
-
-	const MPoly *mp;
-	int mp_index;
-
-	/* First check we do have a tris/quads only mesh. */
-	for (mp = mpolys, mp_index = 0; mp_index < numPolys; mp++, mp_index++) {
-		if (mp->totloop > 4) {
-			BKE_report(reports, RPT_ERROR, "Tangent space can only be computed for tris/quads, aborting");
-			return;
-		}
-	}
-
-	/* Compute Mikktspace's tangent normals. */
-	mesh_to_tangent.mpolys = mpolys;
-	mesh_to_tangent.mloops = mloops;
-	mesh_to_tangent.mverts = mverts;
-	mesh_to_tangent.luvs = loopuvs;
-	mesh_to_tangent.lnors = loopnors;
-	mesh_to_tangent.tangents = r_looptangent;
-	mesh_to_tangent.num_polys = numPolys;
-
-	s_context.m_pUserData = &mesh_to_tangent;
-	s_context.m_pInterface = &s_interface;
-	s_interface.m_getNumFaces = get_num_faces;
-	s_interface.m_getNumVerticesOfFace = get_num_verts_of_face;
-	s_interface.m_getPosition = get_position;
-	s_interface.m_getTexCoord = get_texture_coordinate;
-	s_interface.m_getNormal = get_normal;
-	s_interface.m_setTSpaceBasic = set_tspace;
-
-	/* 0 if failed */
-	if (genTangSpaceDefault(&s_context) == false) {
-		BKE_report(reports, RPT_ERROR, "Mikktspace failed to generate tangents for this mesh!");
-	}
-}
-
-/**
- * Wrapper around BKE_mesh_loop_tangents_ex, which takes care of most boiling code.
- * \note
- * - There must be a valid loop's CD_NORMALS available.
- * - The mesh should be made of only tris and quads!
- */
-void BKE_mesh_loop_tangents(Mesh *mesh, const char *uvmap, float (*r_looptangents)[4], ReportList *reports)
-{
-	MLoopUV *loopuvs;
-	float (*loopnors)[3];
-
-	/* Check we have valid texture coordinates first! */
-	if (uvmap) {
-		loopuvs = CustomData_get_layer_named(&mesh->ldata, CD_MLOOPUV, uvmap);
-	}
-	else {
-		loopuvs = CustomData_get_layer(&mesh->ldata, CD_MLOOPUV);
-	}
-	if (!loopuvs) {
-		BKE_reportf(reports, RPT_ERROR, "Tangent space computation needs an UVMap, \"%s\" not found, aborting", uvmap);
-		return;
-	}
-
-	loopnors = CustomData_get_layer(&mesh->ldata, CD_NORMAL);
-	if (!loopnors) {
-		BKE_report(reports, RPT_ERROR, "Tangent space computation needs loop normals, none found, aborting");
-		return;
-	}
-
-	BKE_mesh_loop_tangents_ex(mesh->mvert, mesh->totvert, mesh->mloop, r_looptangents,
-	                          loopnors, loopuvs, mesh->totloop, mesh->mpoly, mesh->totpoly, reports);
-}
-
-/** \} */
-
-
-/* -------------------------------------------------------------------- */
-
 /** \name Polygon Calculations
  * \{ */
 
diff --git a/source/blender/blenkernel/intern/mesh_tangent.c b/source/blender/blenkernel/intern/mesh_tangent.c
new file mode 100644
index 00000000000..7b953337909
--- /dev/null
+++ b/source/blender/blenkernel/intern/mesh_tangent.c
@@ -0,0 +1,684 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
+ * All rights reserved.
+ *
+ * Contributor(s): Blender Foundation
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/blenkernel/intern/mesh_tangent.c
+ *  \ingroup bke
+ *
+ * Functions to evaluate mesh tangents.
+ */
+
+#include <limits.h>
+
+#include "MEM_guardedalloc.h"
+
+#include "DNA_mesh_types.h"
+#include "DNA_meshdata_types.h"
+
+#include "BLI_utildefines.h"
+#include "BLI_math.h"
+#include "BLI_stack.h"
+#include "BLI_task.h"
+
+#include "BKE_customdata.h"
+#include "BKE_global.h"
+#include "BKE_mesh.h"
+#include "BKE_mesh_tangent.h"
+#include "BKE_report.h"
+
+#include "BLI_strict_flags.h"
+
+#include "atomic_ops.h"
+#include "mikktspace.h"
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Tangent Calculations (Single Layer)
+ * \{ */
+
+/* Tangent space utils. */
+
+/* User data. */
+typedef struct {
+	const MPoly *mpolys;   /* faces */
+	const MLoop *mloops;   /* faces's vertices */
+	const MVert *mverts;   /* vertices */
+	const MLoopUV *luvs;   /* texture coordinates */
+	float (*lnors)[3];     /* loops' normals */
+	float (*tangents)[4];  /* output tangents */
+	int num_polys;         /* number of polygons */
+} BKEMeshToTangent;
+
+/* Mikktspace's API */
+static int get_num_faces(const SMikkTSpaceContext *pContext)
+{
+	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
+	return p_mesh->num_polys;
+}
+
+static int get_num_verts_of_face(const SMikkTSpaceContext *pContext, const int face_idx)
+{
+	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
+	return p_mesh->mpolys[face_idx].totloop;
+}
+
+static void get_position(const SMikkTSpaceContext *pContext, float r_co[3], const int face_idx, const int vert_idx)
+{
+	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
+	const int loop_idx = p_mesh->mpolys[face_idx].loopstart + vert_idx;
+	copy_v3_v3(r_co, p_mesh->mverts[p_mesh->mloops[loop_idx].v].co);
+}
+
+static void get_texture_coordinate(const SMikkTSpaceContext *pContext, float r_uv[2], const int face_idx,
+                                   const int vert_idx)
+{
+	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
+	copy_v2_v2(r_uv, p_mesh->luvs[p_mesh->mpolys[face_idx].loopstart + vert_idx].uv);
+}
+
+static void get_normal(const SMikkTSpaceContext *pContext, float r_no[3], const int face_idx, const int vert_idx)
+{
+	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
+	copy_v3_v3(r_no, p_mesh->lnors[p_mesh->mpolys[face_idx].loopstart + vert_idx]);
+}
+
+static void set_tspace(const SMikkTSpaceContext *pContext, const float fv_tangent[3], const float face_sign,
+                       const int face_idx, const int vert_idx)
+{
+	BKEMeshToTangent *p_mesh = (BKEMeshToTangent *)pContext->m_pUserData;
+	float *p_res = p_mesh->tangents[p_mesh->mpolys[face_idx].loopstart + vert_idx];
+	copy_v3_v3(p_res, fv_tangent);
+	p_res[3] = face_sign;
+}
+
+/**
+ * Compute simplified tangent space normals, i.e. tangent vector + sign of bi-tangent one, which combined with
+ * split normals can be used to recreate the full tangent space.
+ * Note: * The mesh should be made of only tris and quads!
+ */
+void BKE_mesh_calc_loop_tangent_single_ex(
+        const MVert *mverts, const int UNUSED(numVerts), const MLoop *mloops,
+        float (*r_looptangent)[4], float (*loopnors)[3], const MLoopUV *loopuvs,
+        const int UNUSED(numLoops), const MPoly *mpolys, const int numPolys,
+        ReportList *reports)
+{
+	BKEMeshToTangent mesh_to_tangent = {NULL};
+	SMikkTSpaceContext s_context = {NULL};
+	SMikkTSpaceInterface s_interface = {NULL};
+
+	const MPoly *mp;
+	int mp_index;
+
+	/* First check we do have a tris/quads only mesh. */
+	for (mp = mpolys, mp_index = 0; mp_index < numPolys; mp++, mp_index++) {
+		if (mp->totloop > 4) {
+			BKE_report(reports, RPT_ERROR, "Tangent space can only be computed for tris/quads, aborting");
+			return;
+		}
+	}
+
+	/* Compute Mikktspace's tangent normals. */
+	mesh_to_tangent.mpolys = mpolys;
+	mesh_to_tangent.mloops = mloops;
+	mesh_to_tangent.mverts = mverts;
+	mesh_to_tangent.luvs = loopuvs;
+	mesh_to_tangent.lnors = loopnors;
+	mesh_to_tangent.tangents = r_looptangent;
+	mesh_to_tangent.num_polys = numPolys;
+
+	s_context.m_pUserData = &mesh_to_tangent;
+	s_context.m_pInterface = &s_interface;
+	s_interface.m_getNumFaces = get_num_faces;
+	s_interface.m_getNumVerticesOfFace = get_num_verts_of_face;
+	s_interface.m_getPosition = get_position;
+	s_interface.m_getTexCoord = get_texture_coordinate;
+	s_interface.m_getNormal = get_normal;
+	s_interface.m_setTSpaceBasic = set_tspace;
+
+	/* 0 if failed */
+	if (genTangSpaceDefault(&s_context) == false) {
+		BKE_report(reports, RPT_ERROR, "Mikktspace failed to generate tangents for this mesh!");
+	}
+}
+
+/**
+ * Wrapper around BKE_mesh_calc_loop_tangent_single_ex, which takes care of most boiling code.
+ * \note
+ * - There must be a valid loop's CD_NORMALS available.
+ * - The mesh should be made of only tris and quads!
+ */
+void BKE_mesh_calc_loop_tangent_single(Mesh *mesh, const char *uvmap, float (*r_looptangents)[4], ReportList *reports)
+{
+	MLoopUV *loopuvs;
+	float (*loopnors)[3];
+
+	/* Check we have valid texture coordinates first! */
+	if (uvmap) {
+		loopuvs = CustomData_get_layer_named(&mesh->ldata, CD_MLOOPUV, uvmap);
+	}
+	else {
+		loopuvs = CustomData_get_layer(&mesh->ldata, CD_MLOOPUV);
+	}
+	if (!loopuvs) {
+		BKE_reportf(reports, RPT_ERROR, "Tangent space computation needs an UVMap, \"%s\" not found, aborting", uvmap);
+		return;
+	}
+
+	loopnors = CustomData_get_layer(&mesh->ldata, CD_NORMAL);
+	if (!loopnors) {
+		BKE_report(reports, RPT_ERROR, "Tangent space computation needs loop normals, none found, aborting");
+		return;
+	}
+
+	BKE_mesh_calc_loop_tangent_single_ex(mesh->mvert, mesh->totvert, mesh->mloop, r_looptangents,
+	                          loopnors, loopuvs, mesh->totloop, mesh->mpoly, mesh->totpoly, reports);
+}
+
+/** \} */
+
+
+/* -------------------------------------------------------------------- */
+
+/** \name Mesh Tangent Calculations (All Layers)
+ * \{ */
+
+
+/* Necessary complexity to handle looptri's as quads for correct tangents */
+#define USE_LOOPTRI_DETECT_QUADS
+
+typedef struct {
+	const float (*precomputedFaceNormals)[3];
+	const float (*precomputedLoopNormals)[3];
+	const MLoopTri *looptri;
+	MLoopUV *mloopuv;   /* texture coordinates */
+	const MPoly *mpoly;       /* indices */
+	const MLoop *mloop;       /* indices */
+	const MVert *mvert;       /* vertices & normals */
+	const float (*orco)[3];
+	float (*tangent)[4];    /* destination */
+	int numTessFaces;
+
+#ifdef USE_LOOPTRI_DETECT_QUADS
+	/* map from 'fake' face index to looptri,
+	 * quads will point to the first looptri of the quad */
+	const int    *face_as_quad_map;
+	int       num_face_as_quad_map;
+#endif
+
+} SGLSLMeshToTangent;
+
+/* interface */
+#include "mikktspace.h"
+
+static int dm_ts_GetNumFaces(const SMikkTSpaceContext *pContext)
+{
+	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
+
+#ifdef USE_LOOPTRI_DETECT_QUADS
+	return pMesh->num_face_as_quad_map;
+#else
+	return pMesh->numTessFaces;
+#endif
+}
+
+static int dm_ts_GetNumVertsOfFace(const SMikkTSpaceContext *pContext, const int face_num)
+{
+#ifdef USE_LOOPTRI_DETECT_QUADS
+	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
+	if (pMesh->face_as_quad_map) {
+		const MLoopTri *lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
+		const MPoly *mp = &pMesh->mpoly[lt->poly];
+		if (mp->totloop == 4) {
+			return 4;
+		}
+	}
+	return 3;
+#else
+	UNUSED_VARS(pContext, face_num);
+	return 3;
+#endif
+}
+
+static void dm_ts_GetPosition(
+        const SMikkTSpaceContext *pContext, float r_co[3],
+        const int face_num, const int vert_index)
+{
+	//assert(vert_index >= 0 && vert_index < 4);
+	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
+	const MLoopTri *lt;
+	uint loop_index;
+	const float *co;
+
+#ifdef USE_LOOPTRI_DETECT_QUADS
+	if (pMesh->face_as_quad_map) {
+		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
+		const MPoly *mp = &pMesh->mpoly[lt->poly];
+		if (mp->totloop == 4) {
+			loop_index = (uint)(mp->loopstart + vert_index);
+			goto finally;
+		}
+		/* fall through to regular triangle */
+	}
+	else {
+		lt = &pMesh->looptri[face_num];
+	}
+#else
+	lt = &pMesh->looptri[face_num];
+#endif
+	loop_index = lt->tri[vert_index];
+
+finally:
+	co = pMesh->mvert[pMesh->mloop[loop_index].v].co;
+	copy_v3_v3(r_co, co);
+}
+
+static void dm_ts_GetTextureCoordinate(
+        const SMikkTSpaceContext *pContext, float r_uv[2],
+        const int face_num, const int vert_index)
+{
+	//assert(vert_index >= 0 && vert_index < 4);
+	SGLSLMeshToTangent *pMesh = pContext->m_pUserData;
+	const MLoopTri *lt;
+	uint loop_index;
+
+#ifdef USE_LOOPTRI_DETECT_QUADS
+	if (pMesh->face_as_quad_map) {
+		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
+		const MPoly *mp = &pMesh->mpoly[lt->poly];
+		if (mp->totloop == 4) {
+			loop_index = (uint)(mp->loopstart + vert_index);
+			goto finally;
+		}
+		/* fall through to regular triangle */
+	}
+	else {
+		lt = &pMesh->looptri[face_num];
+	}
+#else
+	lt = &pMesh->looptri[face_num];
+#endif
+	loop_index = lt->tri[vert_index];
+
+finally:
+	if (pMesh->mloopuv != NULL) {
+		const float *uv = pMesh->mloopuv[loop_index].uv;
+		copy_v2_v2(r_uv, uv);
+	}
+	else {
+		const float *orco = pMesh->orco[pMesh->mloop[loop_index].v];
+		map_to_sphere(&r_uv[0], &r_uv[1], orco[0], orco[1], orco[2]);
+	}
+}
+
+static void dm_ts_GetNormal(
+        const SMikkTSpaceContext *pContext, float r_no[3],
+        const int face_num, const int vert_index)
+{
+	//assert(vert_index >= 0 && vert_index < 4);
+	SGLSLMeshToTangent *pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+	const MLoopTri *lt;
+	uint loop_index;
+
+#ifdef USE_LOOPTRI_DETECT_QUADS
+	if (pMesh->face_as_quad_map) {
+		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
+		const MPoly *mp = &pMesh->mpoly[lt->poly];
+		if (mp->totloop == 4) {
+			loop_index = (uint)(mp->loopstart + vert_index);
+			goto finally;
+		}
+		/* fall through to regular triangle */
+	}
+	else {
+		lt = &pMesh->looptri[face_num];
+	}
+#else
+	lt = &pMesh->looptri[face_num];
+#endif
+	loop_index = lt->tri[vert_index];
+
+finally:
+	if (pMesh->precomputedLoopNormals) {
+		copy_v3_v3(r_no, pMesh->precomputedLoopNormals[loop_index]);
+	}
+	else if ((pMesh->mpoly[lt->poly].flag & ME_SMOOTH) == 0) {  /* flat */
+		if (pMesh->precomputedFaceNormals) {
+			copy_v3_v3(r_no, pMesh->precomputedFaceNormals[lt->poly]);
+		}
+		else {
+#ifdef USE_LOOPTRI_DETECT_QUADS
+			const MPoly *mp = &pMesh->mpoly[lt->poly];
+			if (mp->totloop == 4) {
+				normal_quad_v3(
+				        r_no,
+				        pMesh->mvert[pMesh->mloop[mp->loopstart + 0].v].co,
+				        pMesh->mvert[pMesh->mloop[mp->loopstart + 1].v].co,
+				        pMesh->mvert[pMesh->mloop[mp->loopstart + 2].v].co,
+				        pMesh->mvert[pMesh->mloop[mp->loopstart + 3].v].co);
+			}
+			else
+#endif
+			{
+				normal_tri_v3(
+				        r_no,
+				        pMesh->mvert[pMesh->mloop[lt->tri[0]].v].co,
+				        pMesh->mvert[pMesh->mloop[lt->tri[1]].v].co,
+				        pMesh->mvert[pMesh->mloop[lt->tri[2]].v].co);
+			}
+		}
+	}
+	else {
+		const short *no = pMesh->mvert[pMesh->mloop[loop_index].v].no;
+		normal_short_to_float_v3(r_no, no);
+	}
+}
+
+static void dm_ts_SetTSpace(
+        const SMikkTSpaceContext *pContext, const float fvTangent[3], const float fSign,
+        const int face_num, const int vert_index)
+{
+	//assert(vert_index >= 0 && vert_index < 4);
+	SGLSLMeshToTangent *pMesh = (SGLSLMeshToTangent *) pContext->m_pUserData;
+	const MLoopTri *lt;
+	uint loop_index;
+
+#ifdef USE_LOOPTRI_DETECT_QUADS
+	if (pMesh->face_as_quad_map) {
+		lt = &pMesh->looptri[pMesh->face_as_quad_map[face_num]];
+		const MPoly *mp = &pMesh->mpoly[lt->poly];
+		if (mp->totloop == 4) {
+			loop_index = (uint)(mp->loopstart + vert_index);
+			goto finally;
+		}
+		/* fall through to regular triangle */
+	}
+	else {
+		lt = &pMesh->looptri[face_num];
+	}
+#else
+	lt = &pMesh->looptri[face_num];
+#endif
+	loop_index = lt->tri[vert_index];
+
+	float *pRes;
+
+finally:
+	pRes = pMesh->tangent[loop_index];
+	copy_v3_v3(pRes, fvTangent);
+	pRes[3] = fSign;
+}
+
+static void DM_calc_loop_tangents_thread(TaskPool * __restrict UNUSED(pool), void *taskdata, int UNUSED(threadid))
+{
+	struct SGLSLMeshToTangent *mesh2tangent = taskdata;
+	/* new computation method */
+	{
+		SMikkTSpaceContext sContext = {NULL};
+		SMikkTSpaceInterface sInterface = {NULL};
+
+		sContext.m_pUserData = mesh2tangent;
+		sContext.m_pInterface = &sInterface;
+		sInterface.m_getNumFaces = dm_ts_GetNumFaces;
+		sInterface.m_getNumVerticesOfFace = dm_ts_GetNumVertsOfFace;
+		sInterface.m_getPosition = dm_ts_GetPosition;
+		sInterface.m_getTexCoord = dm_ts_GetTextureCoordinate;
+		sInterface.m_getNormal = dm_ts_GetNormal;
+		sInterface.m_setTSpaceBasic = dm_ts_SetTSpace;
+
+		/* 0 if failed */
+		genTangSpaceDefault(&sContext);
+	}
+}
+
+void BKE_mesh_add_loop_tangent_named_layer_for_uv(
+        CustomData *uv_data, CustomData *tan_data, int numLoopData,
+        const char *layer_name)
+{
+	if (CustomData_get_named_layer_index(tan_data, CD_TANGENT, layer_name) == -1 &&
+	    CustomData_get_named_layer_index(uv_data, CD_MLOOPUV, layer_name) != -1)
+	{
+		CustomData_add_layer_named(
+		        tan_data, CD_TANGENT, CD_CALLOC, NULL,
+		        numLoopData, layer_name);
+	}
+}
+
+/**
+ * Here we get some useful information such as active uv layer name and search if it is already in tangent_names.
+ * Also, we calculate tangent_mask that works as a descriptor of tangents state.
+ * If tangent_mask has changed, then recalculate tangents.
+ */
+void BKE_mesh_calc_loop_tangent_step_0(
+        const CustomData *loopData, bool calc_active_tangent,
+        const char (*tangent_names)[MAX_NAME], int tangent_names_count,
+        bool *rcalc_act, bool *rcalc_ren, int *ract_uv_n, int *rren_uv_n,
+        char *ract_uv_name, char *rren_uv_name, char *rtangent_mask) {
+	/* Active uv in viewport */
+	int layer_index = CustomData_get_layer_index(loopData, CD_MLOOPUV);
+	*ract_uv_n = CustomData_get_active_layer(loopData, CD_MLOOPUV);
+	ract_uv_name[0] = 0;
+	if (*ract_uv_n != -1) {
+		strcpy(ract_uv_name, loopData->layers[*ract_uv_n + layer_index].name);
+	}
+
+	/* Active tangent in render */
+	*rren_uv_n = CustomData_get_render_layer(loopData, CD_MLOOPUV);
+	rren_uv_name[0] = 0;
+	if (*rren_uv_n != -1) {
+		strcpy(rren_uv_name, loopData->layers[*rren_uv_n + layer_index].name);
+	}
+
+	/* If active tangent not in tangent_names we take it into account */
+	*rcalc_act = false;
+	*rcalc_ren = false;
+	for (int i = 0; i < tangent_names_count; i++) {
+		if (tangent_names[i][0] == 0) {
+			calc_active_tangent = true;
+		}
+	}
+	if (calc_active_tangent) {
+		*rcalc_act = true;
+		*rcalc_ren = true;
+		for (int i = 0; i < tangent_names_count; i++) {
+			if (STREQ(ract_uv_name, tangent_names[i]))
+				*rcalc_act = false;
+			if (STREQ(rren_uv_name, tangent_names[i]))
+				*rcalc_ren = false;
+		}
+	}
+	*rtangent_mask = 0;
+
+	const int uv_layer_num = CustomData_number_of_layers(loopData, CD_MLOOPUV);
+	for (int n = 0; n < uv_layer_num; n++) {
+		const char *name = CustomData_get_layer_name(loopData, CD_MLOOPUV, n);
+		bool add = false;
+		for (int i = 0; i < tangent_names_count; i++) {
+			if (tangent_names[i][0] && STREQ(tangent_names[i], name)) {
+				add = true;
+				break;
+			}
+		}
+		if ((*rcalc_act && ract_uv_name[0] && STREQ(ract_uv_name, name)) ||
+		    (*rcalc_ren && rren_uv_name[0] && STREQ(rren_uv_name, name)))
+		{
+			add = true;
+		}
+		if (add)
+			*rtangent_mask |= (char)(1 << n);
+	}
+}
+
+/**
+ * See: #BKE_editmesh_loop_tangent_calc (matching logic).
+ */
+void BKE_mesh_calc_loop_tangent_ex(
+        const MVert *mvert,
+        const MPoly *mpoly, const uint mpoly_len,
+        const MLoop *mloop,
+        const MLoopTri *looptri,
+        const uint looptri_len,
+
+        CustomData *loopdata,
+        bool calc_active_tangent,
+        const char (*tangent_names)[MAX_NAME], int tangent_names_len,
+        const float (*poly_normals)[3],
+        const float (*loop_normals)[3],
+        const float (*vert_orco)[3],
+        /* result */
+        CustomData *loopdata_out,
+        const uint  loopdata_out_len,
+        char *tangent_mask_curr_p)
+{
+	BLI_assert(CustomData_number_of_layers(loopdata, CD_MLOOPUV) != 0);
+
+	int act_uv_n = -1;
+	int ren_uv_n = -1;
+	bool calc_act = false;
+	bool calc_ren = false;
+	char act_uv_name[MAX_NAME];
+	char ren_uv_name[MAX_NAME];
+	char tangent_mask = 0;
+	char tangent_mask_curr = *tangent_mask_curr_p;
+
+	BKE_mesh_calc_loop_tangent_step_0(
+	        loopdata, calc_active_tangent, tangent_names, tangent_names_len,
+	        &calc_act, &calc_ren, &act_uv_n, &ren_uv_n, act_uv_name, ren_uv_name, &tangent_mask);
+	if ((tangent_mask_curr | tangent_mask) != tangent_mask_curr) {
+		/* Check we have all the needed layers */
+		/* Allocate needed tangent layers */
+		for (int i = 0; i < tangent_names_len; i++)
+			if (tangent_names[i][0])
+				BKE_mesh_add_loop_tangent_named_layer_for_uv(loopdata, loopdata_out, (int)loopdata_out_len, tangent_names[i]);
+		if (calc_act && act_uv_name[0])
+			BKE_mesh_add_loop_tangent_named_layer_for_uv(loopdata, loopdata_out, (int)loopdata_out_len, act_uv_name);
+		if (calc_ren && ren_uv_name[0])
+			BKE_mesh_add_loop_tangent_named_layer_for_uv(loopdata, loopdata_out, (int)loopdata_out_len, ren_uv_name);
+
+#ifdef USE_LOOPTRI_DETECT_QUADS
+		int num_face_as_quad_map;
+		int *face_as_quad_map = NULL;
+
+		/* map faces to quads */
+		if (looptri_len != mpoly_len) {
+			/* over alloc, since we dont know how many ngon or quads we have */
+
+			/* map fake face index to looptri */
+			face_as_quad_map = MEM_mallocN(sizeof(int) * looptri_len, __func__);
+			int k, j;
+			for (k = 0, j = 0; j < (int)looptri_len; k++, j++) {
+				face_as_quad_map[k] = j;
+				/* step over all quads */
+				if (mpoly[looptri[j].poly].totloop == 4) {
+					j++;  /* skips the nest looptri */
+				}
+			}
+			num_face_as_quad_map = k;
+		}
+		else {
+			num_face_as_quad_map = (int)looptri_len;
+		}
+#endif
+
+		/* Calculation */
+		{
+			TaskScheduler *scheduler = BLI_task_scheduler_get();
+			TaskPool *task_pool;
+			task_pool = BLI_task_pool_create(scheduler, NULL);
+
+			tangent_mask_curr = 0;
+			/* Calculate tangent layers */
+			SGLSLMeshToTangent data_array[MAX_MTFACE];
+			const int tangent_layer_num = CustomData_number_of_layers(loopdata_out, CD_TANGENT);
+			for (int n = 0; n < tangent_layer_num; n++) {
+				int index = CustomData_get_layer_index_n(loopdata_out, CD_TANGENT, n);
+				BLI_assert(n < MAX_MTFACE);
+				SGLSLMeshToTangent *mesh2tangent = &data_array[n];
+				mesh2tangent->numTessFaces = (int)looptri_len;
+#ifdef USE_LOOPTRI_DETECT_QUADS
+				mesh2tangent->face_as_quad_map = face_as_quad_map;
+				mesh2tangent->num_face_as_quad_map = num_face_as_quad_map;
+#endif
+				mesh2tangent->mvert = mvert;
+				mesh2tangent->mpoly = mpoly;
+				mesh2tangent->mloop = mloop;
+				mesh2tangent->looptri = looptri;
+				/* Note, we assume we do have tessellated loop normals at this point (in case it is object-enabled),
+				 * have to check this is valid...
+				 */
+				mesh2tangent->precomputedLoopNormals = loop_normals;
+				mesh2tangent->precomputedFaceNormals = poly_normals;
+
+				mesh2tangent->orco = NULL;
+				mesh2tangent->mloopuv = CustomData_get_layer_named(loopdata, CD_MLOOPUV, loopdata->layers[index].name);
+				if (!mesh2tangent->mloopuv) {
+					mesh2tangent->orco = vert_orco;
+					if (!mesh2tangent->orco)
+						continue;
+				}
+				mesh2tangent->tangent = loopdata_out->layers[index].data;
+
+				/* Fill the resulting tangent_mask */
+				int uv_ind = CustomData_get_named_layer_index(
+				        loopdata, CD_MLOOPUV, loopdata_out->layers[index].name);
+				int uv_start = CustomData_get_layer_index(loopdata, CD_MLOOPUV);
+				BLI_assert(uv_ind != -1 && uv_start != -1);
+				BLI_assert(uv_ind - uv_start < MAX_MTFACE);
+				tangent_mask_curr |= (char)(1 << (uv_ind - uv_start));
+				BLI_task_pool_push(task_pool, DM_calc_loop_tangents_thread, mesh2tangent, false, TASK_PRIORITY_LOW);
+			}
+
+			BLI_assert(tangent_mask_curr == tangent_mask);
+			BLI_task_pool_work_and_wait(task_pool);
+			BLI_task_pool_free(task_pool);
+		}
+#ifdef USE_LOOPTRI_DETECT_QUADS
+		if (face_as_quad_map) {
+			MEM_freeN(face_as_quad_map);
+		}
+#undef USE_LOOPTRI_DETECT_QUADS
+
+#endif
+
+		*tangent_mask_curr_p = tangent_mask_curr;
+
+		int uv_index, tan_index;
+
+		/* Update active layer index */
+		uv_index = CustomData_get_layer_index_n(loopdata, CD_MLOOPUV, act_uv_n);
+		if (uv_index != -1) {
+			tan_index = CustomData_get_named_layer_index(loopdata_out, CD_TANGENT, loopdata->layers[uv_index].name);
+			CustomData_set_layer_active_index(loopdata_out, CD_TANGENT, tan_index);
+		}
+
+		/* Update render layer index */
+		uv_index = CustomData_get_layer_index_n(loopdata, CD_MLOOPUV, ren_uv_n);
+		if (uv_index != -1) {
+			tan_index = CustomData_get_named_layer_index(loopdata_out, CD_TANGENT, loopdata->layers[uv_index].name);
+			CustomData_set_layer_render_index(loopdata_out, CD_TANGENT, tan_index);
+		}
+	}
+}
+
+/** \} */
diff --git a/source/blender/draw/intern/draw_cache_impl_mesh.c b/source/blender/draw/intern/draw_cache_impl_mesh.c
index 27580958504..62be8bab7ce 100644
--- a/source/blender/draw/intern/draw_cache_impl_mesh.c
+++ b/source/blender/draw/intern/draw_cache_impl_mesh.c
@@ -45,6 +45,7 @@
 #include "BKE_editmesh.h"
 #include "BKE_editmesh_tangent.h"
 #include "BKE_mesh.h"
+#include "BKE_mesh_tangent.h"
 #include "BKE_texture.h"
 
 #include "bmesh.h"
@@ -497,18 +498,45 @@ static MeshRenderData *mesh_render_data_create(Mesh *me, const int types)
 				}
 				else {
 #undef me
-					if (!CustomData_has_layer(cd_ldata, CD_NORMAL)) {
-						BKE_mesh_calc_normals_split(me);
-					}
 
-					float (*loopnors)[3] = CustomData_get_layer(cd_ldata, CD_NORMAL);
+					if (!CustomData_has_layer(&rdata->cd.output.ldata, CD_MLOOPTANGENT)) {
+						if (!CustomData_has_layer(cd_ldata, CD_NORMAL)) {
+							BKE_mesh_calc_normals_split(me);
+						}
+
+						bool calc_active_tangent = false;
+						const float (*poly_normals)[3] = rdata->poly_normals;
+						const float (*loop_normals)[3] = CustomData_get_layer(cd_ldata, CD_NORMAL);
+						char tangent_names[MAX_MTFACE][MAX_NAME];
+						int tangent_names_len = 0;
+						for (tangent_names_len = 0; tangent_names_len < rdata->cd.layers.uv_len; tangent_names_len++) {
+							BLI_strncpy(
+							        tangent_names[tangent_names_len],
+							        CustomData_get_layer_name(cd_ldata, CD_MLOOPUV, tangent_names_len), MAX_NAME);
+						}
+
+						BKE_mesh_calc_loop_tangent_ex(
+						        me->mvert,
+						        me->mpoly, me->totpoly,
+						        me->mloop,
+						        rdata->mlooptri, rdata->tri_len,
+						        cd_ldata,
+						        calc_active_tangent,
+						        tangent_names, tangent_names_len,
+						        poly_normals, loop_normals,
+						        rdata->orco,
+						        &rdata->cd.output.ldata, me->totloop,
+						        &rdata->cd.output.tangent_mask);
 
-					rdata->cd.layers.tangent[i] = CustomData_add_layer(
-					        cd_ldata, CD_MLOOPTANGENT, CD_CALLOC, NULL, me->totloop);
-					CustomData_set_layer_flag(cd_ldata, CD_MLOOPTANGENT, CD_FLAG_TEMPORARY);
+						/* If we store tangents in the mesh, set temporary. */
+#if 0
+						CustomData_set_layer_flag(cd_ldata, CD_MLOOPTANGENT, CD_FLAG_TEMPORARY);
+#endif
+					}
+
+					rdata->cd.layers.tangent[i] = CustomData_get_layer_n(&rdata->cd.output.ldata, CD_TANGENT, i);
+					BLI_assert(rdata->cd.layers.tangent[i] != NULL);
 
-					BKE_mesh_loop_tangents_ex(me->mvert, me->totvert, me->mloop, rdata->cd.layers.tangent[i],
-					      loopnors, rdata->cd.layers.uv[i], me->totloop, me->mpoly, me->totpoly, NULL);
 #define me DONT_USE_THIS
 #ifdef  me /* quiet warning */
 #endif
@@ -526,7 +554,7 @@ static MeshRenderData *mesh_render_data_create(Mesh *me, const int types)
 #undef me
 	}
 
-	return rdata;
+		return rdata;
 }
 
 static void mesh_render_data_free(MeshRenderData *rdata)
diff --git a/source/blender/makesrna/intern/rna_mesh_api.c b/source/blender/makesrna/intern/rna_mesh_api.c
index 9b0a25560f9..677397eb859 100644
--- a/source/blender/makesrna/intern/rna_mesh_api.c
+++ b/source/blender/makesrna/intern/rna_mesh_api.c
@@ -48,6 +48,7 @@
 #include "DNA_mesh_types.h"
 
 #include "BKE_mesh.h"
+#include "BKE_mesh_tangent.h"
 #include "BKE_mesh_mapping.h"
 #include "ED_mesh.h"
 
@@ -92,7 +93,7 @@ static void rna_Mesh_calc_tangents(Mesh *mesh, ReportList *reports, const char *
 		BKE_mesh_calc_normals_split(mesh);
 	}
 
-	BKE_mesh_loop_tangents(mesh, uvmap, r_looptangents, reports);
+	BKE_mesh_calc_loop_tangent_single(mesh, uvmap, r_looptangents, reports);
 }
 
 static void rna_Mesh_free_tangents(Mesh *mesh)