[Mesa-dev] [RFC][PATCH] vbo: do not restore all the arrayobj stuff if the bufobj is deleted

[Yuanhan Liu]

I hope I can find something from OpenGL spec to support this. Badly, I
didn't make it with a simply searching.

Basically, it's an issue that should we restore all the arrayobj stuff
if the bufobj is deleted? Say, in a following case:

    glGenBuffersARB(2, bufname);

    glBindBufferARB(GL_ARRAY_BUFFER_ARB, bufname[1]);

    glBindBufferARB(GL_ARRAY_BUFFER_ARB, bufname[0]);
    glVertexPointer(2, GL_INT, 0, NULL);

    glPushClientAttrib(GL_CLIENT_VERTEX_ARRAY_BIT);
    glDeleteBuffersARB(1, bufname);  /* This would delete bufname[0] */
    glPopClientAttrib();

Then what's the expected value of the following two queries:
    glGetIntegerv(GL_ARRAY_BUFFER_BINDING_ARB, &val1);
    glGetIntegerv(GL_VERTEX_ARRAY_BUFFER_BINDING_ARB, &val2);

The old code would make val1 and val2 both to be bufname[0]. Well, this
patch keep the val1 but let the val2 to be 0.

I know this patch is ugly, but I'd heard about your comments?

Signed-off-by: Yuanhan Liu <yuanhan.liu at linux.intel.com>
---
 src/mesa/main/attrib.c |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/mesa/main/attrib.c b/src/mesa/main/attrib.c
index 2f391c5..d5559fd 100644
--- a/src/mesa/main/attrib.c
+++ b/src/mesa/main/attrib.c
@@ -1461,6 +1461,8 @@ _mesa_PopClientAttrib(void)
          case GL_CLIENT_VERTEX_ARRAY_BIT: {
 	    struct gl_array_attrib * data =
 	      (struct gl_array_attrib *) node->data;
+            int bufobj_deleted =
+	       _mesa_lookup_bufferobj(ctx, data->ArrayBufferObj->Name) == NULL;
 
             adjust_buffer_object_ref_counts(ctx->Array.ArrayObj, -1);
 	 
@@ -1479,8 +1481,11 @@ _mesa_PopClientAttrib(void)
                                 data->ElementArrayBufferObj->Name);
 #endif
 
-	    memcpy( ctx->Array.ArrayObj, data->ArrayObj,
-		    sizeof( struct gl_array_object ) );
+            /* if the object is deleted, don't restore all the arrayobj stuff */
+            if (!bufobj_deleted) {
+	       memcpy( ctx->Array.ArrayObj, data->ArrayObj,
+		       sizeof( struct gl_array_object ) );
+            }
 
 	    FREE( data->ArrayObj );
 	    
-- 
1.7.4.4