1 files changed, 49 insertions, 4 deletions

diff --git a/src/mesa/main/fbobject.c b/src/mesa/main/fbobject.c
index 1a2e9b1da6f..48b9904642a 100644
--- a/src/mesa/main/fbobject.c
+++ b/src/mesa/main/fbobject.c
@@ -147,6 +147,8 @@ invalidate_framebuffer(struct gl_framebuffer *fb)
 /**
  * Given a GL_*_ATTACHMENTn token, return a pointer to the corresponding
  * gl_renderbuffer_attachment object.
+ * This function is only used for user-created FB objects, not the
+ * default / window-system FB object.
  * If \p attachment is GL_DEPTH_STENCIL_ATTACHMENT, return a pointer to
  * the depth buffer attachment point.
  */
@@ -156,6 +158,8 @@ _mesa_get_attachment(GLcontext *ctx, struct gl_framebuffer *fb,
 {
    GLuint i;
 
+   assert(fb->Name > 0);
+
    switch (attachment) {
    case GL_COLOR_ATTACHMENT0_EXT:
    case GL_COLOR_ATTACHMENT1_EXT:
@@ -195,6 +199,45 @@ _mesa_get_attachment(GLcontext *ctx, struct gl_framebuffer *fb,
 
 
 /**
+ * As above, but only used for getting attachments of the default /
+ * window-system framebuffer (not user-created framebuffer objects).
+ */
+static struct gl_renderbuffer_attachment *
+_mesa_get_fb0_attachment(GLcontext *ctx, struct gl_framebuffer *fb,
+                         GLenum attachment)
+{
+   assert(fb->Name == 0);
+
+   switch (attachment) {
+   case GL_FRONT_LEFT:
+      return &fb->Attachment[BUFFER_FRONT_LEFT];
+   case GL_FRONT_RIGHT:
+      return &fb->Attachment[BUFFER_FRONT_RIGHT];
+   case GL_BACK_LEFT:
+      return &fb->Attachment[BUFFER_BACK_LEFT];
+   case GL_BACK_RIGHT:
+      return &fb->Attachment[BUFFER_BACK_RIGHT];
+   case GL_AUX0:
+      if (fb->Visual.numAuxBuffers == 1) {
+         return &fb->Attachment[BUFFER_AUX0];
+      }
+      return NULL;
+   case GL_DEPTH_BUFFER:
+      /* fall-through / new in GL 3.0 */
+   case GL_DEPTH_ATTACHMENT_EXT:
+      return &fb->Attachment[BUFFER_DEPTH];
+   case GL_STENCIL_BUFFER:
+      /* fall-through / new in GL 3.0 */
+   case GL_STENCIL_ATTACHMENT_EXT:
+      return &fb->Attachment[BUFFER_STENCIL];
+   default:
+      return NULL;
+   }
+}
+
+
+
+/**
  * Remove any texture or renderbuffer attached to the given attachment
  * point.  Update reference counts, etc.
  */
@@ -1878,12 +1921,14 @@ _mesa_GetFramebufferAttachmentParameterivEXT(GLenum target, GLenum attachment,
    }
 
    if (buffer->Name == 0) {
-      _mesa_error(ctx, GL_INVALID_OPERATION,
-                  "glGetFramebufferAttachmentParameterivEXT");
-      return;
+      /* the default / window-system FBO */
+      att = _mesa_get_fb0_attachment(ctx, buffer, attachment);
+   }
+   else {
+      /* user-created framebuffer FBO */
+      att = _mesa_get_attachment(ctx, buffer, attachment);
    }
 
-   att = _mesa_get_attachment(ctx, buffer, attachment);
    if (att == NULL) {
       _mesa_error(ctx, GL_INVALID_ENUM,
                   "glGetFramebufferAttachmentParameterivEXT(attachment)");