Upgrades to the UVProject modifier:

 - New perspective projection capability. If a camera is used as the
   projection object, the modifier detects whether to do perspective or
   orthographic projection based on the camera type. If any other object
   type is used as the projection object, orthographic projection is used.
 - Orthographic projection actually works properly now.
 - The projected UVs are scaled and offset so that the image is centred in
   the projecting camera's view.
 - AspX and AspY inputs have been added to control the aspect ratio of the
   projected UVs.

Also:
 - I have added the Mat4MulVec3Project() function to BLI_arithb.h; this
   function converts a 3-dimensional vector to homogeneous coordinates
   (4-dimensional, with the 4th dimension set to 1), multiplies it with the
   given matrix, then projects it back to 3 dimensions by dividing through
   with the 4th dimension. This is useful when using projection matrices.

5 files changed, 108 insertions, 33 deletions

diff --git a/source/blender/blenkernel/intern/modifier.c b/source/blender/blenkernel/intern/modifier.c
index d87d8b528d9..92a4df5ca27 100644
--- a/source/blender/blenkernel/intern/modifier.c
+++ b/source/blender/blenkernel/intern/modifier.c
@@ -2477,6 +2477,7 @@ static void uvprojectModifier_initData(ModifierData *md)
 	umd->image = NULL;
 	umd->flags = MOD_UVPROJECT_ADDUVS;
 	umd->num_projectors = 1;
+	umd->aspectx = umd->aspecty = 1.0f;
 }
 
 static void uvprojectModifier_copyData(ModifierData *md, ModifierData *target)
@@ -2490,6 +2491,8 @@ static void uvprojectModifier_copyData(ModifierData *md, ModifierData *target)
 	tumd->image = umd->image;
 	tumd->flags = umd->flags;
 	tumd->num_projectors = umd->num_projectors;
+	tumd->aspectx = umd->aspectx;
+	tumd->aspecty = umd->aspecty;
 }
 
 static void uvprojectModifier_foreachObjectLink(ModifierData *md, Object *ob,
@@ -2531,7 +2534,7 @@ static void uvprojectModifier_updateDepgraph(ModifierData *md,
 
 typedef struct Projector {
 	Object *ob;				/* object this projector is derived from */
-	float imat[4][4];		/* world space -> projector space matrix */ 
+	float projmat[4][4];	/* projection matrix */ 
 	float normal[3];		/* projector normal in world space */
 } Projector;
 
@@ -2546,6 +2549,10 @@ static DerivedMesh *uvprojectModifier_do(UVProjectModifierData *umd,
 	int new_tfaces = 0;
 	Projector projectors[MOD_UVPROJECT_MAXPROJECTORS];
 	int num_projectors = 0;
+	float aspect;
+	
+	if(umd->aspecty != 0) aspect = umd->aspectx / umd->aspecty;
+	else aspect = 1.0f;
 
 	for(i = 0; i < umd->num_projectors; ++i)
 		if(umd->projectors[i])
@@ -2573,38 +2580,79 @@ static DerivedMesh *uvprojectModifier_do(UVProjectModifierData *umd,
 	for(i = 0, co = coords; i < numVerts; ++i, ++co)
 		Mat4MulVecfl(ob->obmat, *co);
 
-	if(num_projectors == 1) {
-		float imat[4][4];
-
-		/* get projector space matrix */
-		Mat4Invert(imat, projectors[0].ob->obmat);
-		if(projectors[0].ob->type == OB_CAMERA) {
-			Camera *cam = (Camera *)projectors[0].ob->data;
-			if(cam->type == CAM_ORTHO)
-				Mat4MulFloat3(imat[0], 1 / cam->ortho_scale);
-		}
+	/* calculate a projection matrix and normal for each projector */
+	for(i = 0; i < num_projectors; ++i) {
+		float tmpmat[4][4];
+		float offsetmat[4][4];
+
+		/* calculate projection matrix */
+		Mat4Invert(projectors[i].projmat, projectors[i].ob->obmat);
+
+		if(projectors[i].ob->type == OB_CAMERA) {
+			Camera *cam = (Camera *)projectors[i].ob->data;
+			if(cam->type == CAM_PERSP) {
+				float perspmat[4][4];
+				float xmax; 
+				float xmin;
+				float ymax;
+				float ymin;
+				float pixsize = cam->clipsta * 32.0 / cam->lens;
+
+				if(aspect > 1.0f) {
+					xmax = 0.5f * pixsize; 
+					ymax = xmax / aspect;
+				} else {
+					ymax = 0.5f * pixsize;
+					xmax = ymax * aspect; 
+				}
+				xmin = -xmax;
+				ymin = -ymax;
+
+				i_window(xmin, xmax, ymin, ymax,
+				         cam->clipsta, cam->clipend, perspmat);
+				Mat4MulMat4(tmpmat, projectors[i].projmat, perspmat);
+			} else if(cam->type == CAM_ORTHO) {
+				float orthomat[4][4];
+				float xmax; 
+				float xmin;
+				float ymax;
+				float ymin;
+
+				if(aspect > 1.0f) {
+					xmax = 0.5f * cam->ortho_scale; 
+					ymax = xmax / aspect;
+				} else {
+					ymax = 0.5f * cam->ortho_scale;
+					xmax = ymax * aspect; 
+				}
+				xmin = -xmax;
+				ymin = -ymax;
 
-		/* convert coords to projector space */
-		for(i = 0, co = coords; i < numVerts; ++i, ++co)
-			Mat4MulVecfl(imat, *co);
-	} else {
-		/* calculate a world space -> projector space matrix and normal 
-		 * for each projector
-		 */
-		for(i = 0; i < num_projectors; ++i) {
-			Mat4Invert(projectors[i].imat, projectors[i].ob->obmat);
-			if(projectors[i].ob->type == OB_CAMERA) {
-				Camera *cam = (Camera *)projectors[i].ob->data;
-				if(cam->type == CAM_ORTHO)
-					Mat4MulFloat3(*projectors[i].imat, 1 / cam->ortho_scale);
+				i_ortho(xmin, xmax, ymin, ymax,
+				        cam->clipsta, cam->clipend, orthomat);
+				Mat4MulMat4(tmpmat, projectors[i].projmat, orthomat);
 			}
-			projectors[i].normal[0] = 0;
-			projectors[i].normal[1] = 0;
-			projectors[i].normal[2] = 1;
-			Mat4Mul3Vecfl(projectors[i].ob->obmat, projectors[i].normal);
+		} else {
+			Mat4CpyMat4(tmpmat, projectors[i].projmat);
 		}
+
+		Mat4One(offsetmat);
+		Mat4MulFloat3(offsetmat[0], 0.5);
+		offsetmat[3][0] = offsetmat[3][1] = offsetmat[3][2] = 0.5;
+		Mat4MulMat4(projectors[i].projmat, tmpmat, offsetmat);
+
+		/* calculate worldspace projector normal (for best projector test) */
+		projectors[i].normal[0] = 0;
+		projectors[i].normal[1] = 0;
+		projectors[i].normal[2] = 1;
+		Mat4Mul3Vecfl(projectors[i].ob->obmat, projectors[i].normal);
 	}
 
+	/* if only one projector, project coords to UVs */
+	if(num_projectors == 1)
+		for(i = 0, co = coords; i < numVerts; ++i, ++co)
+			Mat4MulVec3Project(projectors[0].projmat, *co);
+
 	mface = dm->getFaceArray(dm);
 	numFaces = dm->getNumFaces(dm);
 
@@ -2660,11 +2708,11 @@ static DerivedMesh *uvprojectModifier_do(UVProjectModifierData *umd,
 					}
 				}
 
-				Mat4MulVecfl(best_projector->imat, co1);
-				Mat4MulVecfl(best_projector->imat, co2);
-				Mat4MulVecfl(best_projector->imat, co3);
+				Mat4MulVec3Project(best_projector->projmat, co1);
+				Mat4MulVec3Project(best_projector->projmat, co2);
+				Mat4MulVec3Project(best_projector->projmat, co3);
 				if(mf->v4)
-					Mat4MulVecfl(best_projector->imat, co4);
+					Mat4MulVec3Project(best_projector->projmat, co4);
 
 				/* apply transformed coords as UVs */
 				tface->uv[0][0] = co1[0];
diff --git a/source/blender/blenlib/BLI_arithb.h b/source/blender/blenlib/BLI_arithb.h
index c478262d500..fa7c05cce7c 100644
--- a/source/blender/blenlib/BLI_arithb.h
+++ b/source/blender/blenlib/BLI_arithb.h
@@ -401,6 +401,11 @@ Mat3Clr(
 Mat3One(
 	float m[][3]
 );
+	void
+Mat4MulVec3Project(
+	float mat[][4],
+	float *vec
+);
 	void 
 Mat4MulVec(
 	float mat[][4],
diff --git a/source/blender/blenlib/intern/arithb.c b/source/blender/blenlib/intern/arithb.c
index fd91a4231f6..de06fd3365d 100644
--- a/source/blender/blenlib/intern/arithb.c
+++ b/source/blender/blenlib/intern/arithb.c
@@ -838,6 +838,18 @@ void Mat4Mul3Vecfl( float mat[][4], float *vec)
 	vec[2]= x*mat[0][2] + y*mat[1][2] + mat[2][2]*vec[2];
 }
 
+void Mat4MulVec3Project(float mat[][4], float *vec)
+{
+	float w;
+
+	w = vec[0]*mat[0][3] + vec[1]*mat[1][3] + vec[2]*mat[2][3] + mat[3][3];
+	Mat4MulVecfl(mat, vec);
+
+	vec[0] /= w;
+	vec[1] /= w;
+	vec[2] /= w;
+}
+
 void Mat4MulVec4fl( float mat[][4], float *vec)
 {
 	float x,y,z;
diff --git a/source/blender/makesdna/DNA_modifier_types.h b/source/blender/makesdna/DNA_modifier_types.h
index 50cffb89872..1665c0da983 100644
--- a/source/blender/makesdna/DNA_modifier_types.h
+++ b/source/blender/makesdna/DNA_modifier_types.h
@@ -206,6 +206,7 @@ typedef struct UVProjectModifierData {
 	struct Image *image;      /* the image to project */
 	int flags;
 	int num_projectors;
+	float aspectx, aspecty;
 } UVProjectModifierData;
 
 #define MOD_UVPROJECT_MAXPROJECTORS 10
diff --git a/source/blender/src/buttons_editing.c b/source/blender/src/buttons_editing.c
index b5e7d2b539e..78771cac20c 100644
--- a/source/blender/src/buttons_editing.c
+++ b/source/blender/src/buttons_editing.c
@@ -1355,7 +1355,7 @@ static void draw_modifier(uiBlock *block, Object *ob, ModifierData *md, int *xco
 			height = 124;
 			if(dmd->texmapping == MOD_DISP_MAP_OBJECT) height += 19;
 		} else if (md->type==eModifierType_UVProject) {
-			height = 67 + ((UVProjectModifierData *)md)->num_projectors * 19;
+			height = 86 + ((UVProjectModifierData *)md)->num_projectors * 19;
 		} else if (md->type==eModifierType_Decimate) {
 			height = 48;
 		} else if (md->type==eModifierType_Wave) {
@@ -1509,6 +1509,15 @@ static void draw_modifier(uiBlock *block, Object *ob, ModifierData *md, int *xco
 			             lx, (cy-=19), buttonWidth, 19,
 			             &umd->flags, 0, 0, 0, 0,
 			             "Add UV coordinates if missing");
+			uiDefButF(block, NUM, B_MODIFIER_RECALC, "AspX:",
+			          lx, (cy -= 19), buttonWidth / 2, 19, &umd->aspectx,
+			          1, 1000, 100, 2,
+			          "Horizontal Aspect Ratio");
+			uiDefButF(block, NUM, B_MODIFIER_RECALC, "AspY:",
+			          lx + (buttonWidth / 2) + 1, cy, buttonWidth / 2, 19,
+			          &umd->aspecty,
+			          1, 1000, 100, 2,
+			          "Vertical Aspect Ratio");
 			uiDefButI(block, NUM, B_MODIFIER_RECALC, "Projectors:",
 			          lx, (cy -= 19), buttonWidth, 19, &umd->num_projectors,
 			          1, MOD_UVPROJECT_MAXPROJECTORS, 0, 0,