[Mesa-dev] [PATCH 2/2] fbo: Only reuse depth/stencil attachments if the parameters match.

[Paul Berry]

When the user attaches a texture to one of the depth/stencil
attachment points (GL_STENCIL_ATTACHMENT or GL_DEPTH_ATTACHMENT), we
check to see if the same texture is also attached to the other
attachment point, and if so, we re-use the existing texture
attachment.  This is necessary to ensure that if the user later
queries what is attached to GL_DEPTH_STENCIL_ATTACHMENT, they will not
receive an error.

If, however, the user attaches buffers to the two different attachment
points using different parameters (e.g. a different miplevel), then we
can't re-use the existing texture attachment, because it is pointing
to the wrong part of the texture.  This might occur as a transitory
condition if, for example, if the user attached miplevel zero of a
texture to GL_STENCIL_ATTACHMENT and GL_DEPTH_ATTACHMENT, rendered to
it, and then later attempted to attach miplevel one of the same
texture to GL_STENCIL_ATTACHMENT and GL_DEPTH_ATTACHMENT.

This patch causes Mesa to check that GL_STENCIL_ATTACHMENT and
GL_DEPTH_ATTACHMENT use the same attachment parameters before
attempting to share the texture attachment.

On i965 Gen6, fixes piglit tests
"texturing/depthstencil-render-miplevels 1024 depth_stencil_shared"
and "texturing/depthstencil-render-miplevels 1024
stencil_depth_shared".
---
 src/mesa/main/fbobject.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c
index 26ae108..f563694 100644
--- a/src/mesa/main/fbobject.c
+++ b/src/mesa/main/fbobject.c
@@ -2023,7 +2023,11 @@ framebuffer_texture(struct gl_context *ctx, const char *caller, GLenum target,
    _glthread_LOCK_MUTEX(fb->Mutex);
    if (texObj) {
       if (attachment == GL_DEPTH_ATTACHMENT &&
-	   texObj == fb->Attachment[BUFFER_STENCIL].Texture) {
+          texObj == fb->Attachment[BUFFER_STENCIL].Texture &&
+          level == fb->Attachment[BUFFER_STENCIL].TextureLevel &&
+          _mesa_tex_target_to_face(textarget) ==
+          fb->Attachment[BUFFER_STENCIL].CubeMapFace &&
+          zoffset == fb->Attachment[BUFFER_STENCIL].Zoffset) {
 	 /* The texture object is already attached to the stencil attachment
 	  * point. Don't create a new renderbuffer; just reuse the stencil
 	  * attachment's. This is required to prevent a GL error in
@@ -2032,8 +2036,12 @@ framebuffer_texture(struct gl_context *ctx, const char *caller, GLenum target,
 	 reuse_framebuffer_texture_attachment(fb, BUFFER_DEPTH,
 	                                      BUFFER_STENCIL);
       } else if (attachment == GL_STENCIL_ATTACHMENT &&
-	         texObj == fb->Attachment[BUFFER_DEPTH].Texture) {
-	 /* As above, but with depth and stencil juxtaposed. */
+	         texObj == fb->Attachment[BUFFER_DEPTH].Texture &&
+                 level == fb->Attachment[BUFFER_DEPTH].TextureLevel &&
+                 _mesa_tex_target_to_face(textarget) ==
+                 fb->Attachment[BUFFER_DEPTH].CubeMapFace &&
+                 zoffset == fb->Attachment[BUFFER_DEPTH].Zoffset) {
+	 /* As above, but with depth and stencil transposed. */
 	 reuse_framebuffer_texture_attachment(fb, BUFFER_STENCIL,
 	                                      BUFFER_DEPTH);
       } else {
-- 
1.7.7.6