bugfix [#24133] r32303, Mirror Modifier + EditMode + VBO's Problem.

drawing the triangle arrays were only broken up by hidden faces, but switches in material were ignored.
now check for materual context changes.

1 files changed, 42 insertions, 25 deletions

diff --git a/source/blender/blenkernel/intern/cdderivedmesh.c b/source/blender/blenkernel/intern/cdderivedmesh.c
index ca81e216006..e2ecf21bd62 100644
--- a/source/blender/blenkernel/intern/cdderivedmesh.c
+++ b/source/blender/blenkernel/intern/cdderivedmesh.c
@@ -872,34 +872,51 @@ static void cdDM_drawMappedFaces(DerivedMesh *dm, int (*setDrawOptions)(void *us
 		if( !GPU_buffer_legacy(dm) ) {
 			int tottri = dm->drawObject->nelements/3;
 			glShadeModel(GL_SMOOTH);
-
-			for( i = 0; i < tottri; i++ ) {
-				int actualFace = dm->drawObject->faceRemap[i];
-				int drawSmooth = (mf[actualFace].flag & ME_SMOOTH);
-				int draw = 1;
-
-				if(index) {
-					orig = index[actualFace];
-					if(setDrawOptions && orig == ORIGINDEX_NONE)
+			
+			if(tottri == 0) {
+				/* avoid buffer problems in following code */
+			}
+			if(setDrawOptions == NULL) {
+				/* just draw the entire face array */
+				glDrawArrays(GL_TRIANGLES, 0, (tottri-1) * 3);
+			}
+			else {
+				/* we need to check if the next material changes */
+				int next_actualFace= dm->drawObject->faceRemap[0];
+				
+				for( i = 0; i < tottri; i++ ) {
+					//int actualFace = dm->drawObject->faceRemap[i];
+					int actualFace = next_actualFace;
+					int drawSmooth = (mf[actualFace].flag & ME_SMOOTH);
+					int draw = 1;
+
+					if(i != tottri-1)
+						next_actualFace= dm->drawObject->faceRemap[i+1];
+					
+					if(index) {
+						orig = index[actualFace];
+						if(orig == ORIGINDEX_NONE)
+							draw = 0;
+					}
+					else
+						orig = actualFace;
+	
+					if(draw && !setDrawOptions(userData, orig, &drawSmooth))
 						draw = 0;
-				}
-				else
-					orig = actualFace;
-
-				if(draw && setDrawOptions && !setDrawOptions(userData, orig, &drawSmooth))
-					draw = 0;
-
-				/* Goal is to draw as long of a contiguous triangle
-				   array as possible, so draw when we hit either an
-				   invisible triangle or at the end of the array */
-				if(!draw || i == tottri - 1) {
-					if(prevstart != i)
-						/* Add one to the length (via `draw')
-						   if we're drawing at the end of the array */
-						glDrawArrays(GL_TRIANGLES,prevstart*3, (i-prevstart+draw)*3);
-					prevstart = i + 1;
+	
+					/* Goal is to draw as long of a contiguous triangle
+					   array as possible, so draw when we hit either an
+					   invisible triangle or at the end of the array */
+					if(!draw || i == tottri - 1 || mf[actualFace].mat_nr != mf[next_actualFace].mat_nr) {
+						if(prevstart != i)
+							/* Add one to the length (via `draw')
+							   if we're drawing at the end of the array */
+							glDrawArrays(GL_TRIANGLES,prevstart*3, (i-prevstart+draw)*3);
+						prevstart = i + 1;
+					}
 				}
 			}
+
 			glShadeModel(GL_FLAT);
 		}
 		GPU_buffer_unbind();