[Mesa-dev] [PATCH 1/2] mesa: Support BindBuffer{Base, Offset, Range} with a buffer of 0.

[Kenneth Graunke]

_mesa_lookup_bufferobj returns NULL for 0, which caused us to say
"there's no such buffer object" and raise an error, rather than
correctly binding the shared NullBufferObj.

Now you can unbind your buffers.

NOTE: This is a candidate for stable release branches.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/main/transformfeedback.c |   21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/mesa/main/transformfeedback.c b/src/mesa/main/transformfeedback.c
index f2c1435..1bd76d1 100644
--- a/src/mesa/main/transformfeedback.c
+++ b/src/mesa/main/transformfeedback.c
@@ -470,7 +470,12 @@ _mesa_BindBufferRange(GLenum target, GLuint index,
       return;
    }  
 
-   bufObj = _mesa_lookup_bufferobj(ctx, buffer);
+   if (buffer == 0) {
+      bufObj = ctx->Shared->NullBufferObj;
+   } else {
+      bufObj = _mesa_lookup_bufferobj(ctx, buffer);
+   }
+
    if (!bufObj) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glBindBufferRange(invalid buffer=%u)", buffer);
@@ -518,7 +523,12 @@ _mesa_BindBufferBase(GLenum target, GLuint index, GLuint buffer)
       return;
    }
 
-   bufObj = _mesa_lookup_bufferobj(ctx, buffer);
+   if (buffer == 0) {
+      bufObj = ctx->Shared->NullBufferObj;
+   } else {
+      bufObj = _mesa_lookup_bufferobj(ctx, buffer);
+   }
+
    if (!bufObj) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glBindBufferBase(invalid buffer=%u)", buffer);
@@ -574,7 +584,12 @@ _mesa_BindBufferOffsetEXT(GLenum target, GLuint index, GLuint buffer,
       return;
    }
 
-   bufObj = _mesa_lookup_bufferobj(ctx, buffer);
+   if (buffer == 0) {
+      bufObj = ctx->Shared->NullBufferObj;
+   } else {
+      bufObj = _mesa_lookup_bufferobj(ctx, buffer);
+   }
+
    if (!bufObj) {
       _mesa_error(ctx, GL_INVALID_OPERATION,
                   "glBindBufferOffsetEXT(invalid buffer=%u)", buffer);
-- 
1.7.10.3