Fix/change in normal computation, now the viewport uses the same angle

weighted normals as the render engine, and the render engine will copy
normals from the mesh rather than always recalculating them.

Subsurf/multires still use regular vertex normals, but they are expected
to be sufficiently high resolution to not need this.

This means that normal maps displayed in the viewport actually match the
render engine exactly and don't have artifacts due to this discrepancy.
It of course also avoids unexpected surprises where your render normals
look different than your viewport normals.

Subversion bumped to 4 for version patch to recalculate normals.

Patch by Morten Mikkelsen, with some small changes.

1 files changed, 30 insertions, 15 deletions

diff --git a/source/blender/blenkernel/intern/mesh.c b/source/blender/blenkernel/intern/mesh.c
index 247e48a5576..1e29f5c9d3f 100644
--- a/source/blender/blenkernel/intern/mesh.c
+++ b/source/blender/blenkernel/intern/mesh.c
@@ -1278,26 +1278,42 @@ void mesh_calc_normals(MVert *mverts, int numVerts, MFace *mfaces, int numFaces,
 	float *fnors= MEM_callocN(sizeof(*fnors)*3*numFaces, "meshnormals");
 	int i;
 
-	for (i=0; i<numFaces; i++) {
+	for(i=0; i<numFaces; i++) {
 		MFace *mf= &mfaces[i];
 		float *f_no= &fnors[i*3];
 
-		if (mf->v4)
-			normal_quad_v3( f_no,mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co, mverts[mf->v4].co);
+		if(mf->v4)
+			normal_quad_v3(f_no, mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co, mverts[mf->v4].co);
 		else
-			normal_tri_v3( f_no,mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co);
-		
-		add_v3_v3(tnorms[mf->v1], f_no);
-		add_v3_v3(tnorms[mf->v2], f_no);
-		add_v3_v3(tnorms[mf->v3], f_no);
-		if (mf->v4)
-			add_v3_v3(tnorms[mf->v4], f_no);
+			normal_tri_v3(f_no, mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co);
+
+		if((mf->flag&ME_SMOOTH)!=0) {
+			float *n4 = (mf->v4)? tnorms[mf->v4]: NULL;
+			float *c4 = (mf->v4)? mverts[mf->v4].co: NULL;
+
+			accumulate_vertex_normals(tnorms[mf->v1], tnorms[mf->v2], tnorms[mf->v3], n4,
+				f_no, mverts[mf->v1].co, mverts[mf->v2].co, mverts[mf->v3].co, c4);
+		}
+	}
+
+	for(i=0; i<numFaces; i++) {
+		MFace *mf= &mfaces[i];
+
+		if((mf->flag&ME_SMOOTH)==0) {
+			float *f_no= &fnors[i*3];
+			if(is_zero_v3(tnorms[mf->v1])) copy_v3_v3(tnorms[mf->v1], f_no);
+			if(is_zero_v3(tnorms[mf->v2])) copy_v3_v3(tnorms[mf->v2], f_no);
+			if(is_zero_v3(tnorms[mf->v3])) copy_v3_v3(tnorms[mf->v3], f_no);
+			if(mf->v4 && is_zero_v3(tnorms[mf->v4])) copy_v3_v3(tnorms[mf->v4], f_no);
+		}
 	}
-	for (i=0; i<numVerts; i++) {
+
+	/* following Mesh convention; we use vertex coordinate itself for normal in this case */
+	for(i=0; i<numVerts; i++) {
 		MVert *mv= &mverts[i];
 		float *no= tnorms[i];
 		
-		if (normalize_v3(no)==0.0)
+		if(normalize_v3(no) == 0.0f)
 			normalize_v3_v3(no, mv->co);
 
 		normal_float_to_short_v3(mv->no, no);
@@ -1305,11 +1321,10 @@ void mesh_calc_normals(MVert *mverts, int numVerts, MFace *mfaces, int numFaces,
 	
 	MEM_freeN(tnorms);
 
-	if (faceNors_r) {
+	if(faceNors_r)
 		*faceNors_r = fnors;
-	} else {
+	else
 		MEM_freeN(fnors);
-	}
 }
 
 float (*mesh_getVertexCos(Mesh *me, int *numVerts_r))[3]