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, 27 insertions, 11 deletions

diff --git a/source/blender/blenkernel/intern/cdderivedmesh.c b/source/blender/blenkernel/intern/cdderivedmesh.c
index 407d2ded085..b7034a7db8a 100644
--- a/source/blender/blenkernel/intern/cdderivedmesh.c
+++ b/source/blender/blenkernel/intern/cdderivedmesh.c
@@ -1798,7 +1798,7 @@ void CDDM_calc_normals(DerivedMesh *dm)
 	int i;
 	int numVerts = dm->numVertData;
 	int numFaces = dm->numFaceData;
-	MFace *mf;
+	MFace *mfaces;
 	MVert *mv;
 
 	if(numVerts == 0) return;
@@ -1817,27 +1817,43 @@ void CDDM_calc_normals(DerivedMesh *dm)
 										 NULL, dm->numFaceData);
 
 	/* calculate face normals and add to vertex normals */
-	mf = CDDM_get_faces(dm);
-	for(i = 0; i < numFaces; i++, mf++) {
+	mfaces = CDDM_get_faces(dm);
+	for(i = 0; i < numFaces; i++) {
+		MFace * mf = &mfaces[i];
 		float *f_no = face_nors[i];
 
 		if(mf->v4)
-			normal_quad_v3( f_no,mv[mf->v1].co, mv[mf->v2].co, mv[mf->v3].co, mv[mf->v4].co);
+			normal_quad_v3(f_no, mv[mf->v1].co, mv[mf->v2].co, mv[mf->v3].co, mv[mf->v4].co);
 		else
-			normal_tri_v3( f_no,mv[mf->v1].co, mv[mf->v2].co, mv[mf->v3].co);
+			normal_tri_v3(f_no, mv[mf->v1].co, mv[mf->v2].co, mv[mf->v3].co);
 		
-		add_v3_v3(temp_nors[mf->v1], f_no);
-		add_v3_v3(temp_nors[mf->v2], f_no);
-		add_v3_v3(temp_nors[mf->v3], f_no);
-		if(mf->v4)
-			add_v3_v3(temp_nors[mf->v4], f_no);
+		if((mf->flag&ME_SMOOTH)!=0) {
+			float *n4 = (mf->v4)? temp_nors[mf->v4]: NULL;
+			float *c4 = (mf->v4)? mv[mf->v4].co: NULL;
+
+			accumulate_vertex_normals(temp_nors[mf->v1], temp_nors[mf->v2], temp_nors[mf->v3], n4,
+				f_no, mv[mf->v1].co, mv[mf->v2].co, mv[mf->v3].co, c4);
+		}
+	}
+
+	for(i = 0; i < numFaces; i++) {
+		MFace * mf = &mfaces[i];
+
+		if((mf->flag&ME_SMOOTH)==0) {
+			float *f_no = face_nors[i];
+
+			if(is_zero_v3(temp_nors[mf->v1])) copy_v3_v3(temp_nors[mf->v1], f_no);
+			if(is_zero_v3(temp_nors[mf->v2])) copy_v3_v3(temp_nors[mf->v2], f_no);
+			if(is_zero_v3(temp_nors[mf->v3])) copy_v3_v3(temp_nors[mf->v3], f_no);
+			if(mf->v4 && is_zero_v3(temp_nors[mf->v4])) copy_v3_v3(temp_nors[mf->v4], f_no);
+		}
 	}
 
 	/* normalize vertex normals and assign */
 	for(i = 0; i < numVerts; i++, mv++) {
 		float *no = temp_nors[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);