1 files changed, 13 insertions, 1 deletions
diff --git a/src/mesa/vbo/vbo_exec_draw.c b/src/mesa/vbo/vbo_exec_draw.c
index 1d095c772f..7ec431a237 100644
--- a/src/mesa/vbo/vbo_exec_draw.c
+++ b/src/mesa/vbo/vbo_exec_draw.c
@@ -188,7 +188,19 @@ static void vbo_exec_bind_arrays( GLcontext *ctx )
          /* override the default array set above */
          exec->vtx.inputs[attr] = &arrays[attr];
 
-	 arrays[attr].Ptr = (void *)data;
+         if (exec->vtx.bufferobj->Name) {
+            /* a real buffer obj: Ptr is an offset, not a pointer*/
+            int offset;
+            assert(exec->vtx.bufferobj->Pointer);  /* buf should be mapped */
+            offset = (GLbyte *) data - (GLbyte *) exec->vtx.bufferobj->Pointer;
+            assert(offset >= 0);
+            arrays[attr].Ptr = (void *) offset;
+         }
+         else {
+            /* Ptr into ordinary app memory */
+            arrays[attr].Ptr = (void *) data;
+         }
+
 	 arrays[attr].Size = exec->vtx.attrsz[src];
 	 arrays[attr].StrideB = exec->vtx.vertex_size * sizeof(GLfloat);
 	 arrays[attr].Stride = exec->vtx.vertex_size * sizeof(GLfloat);