+
+ /* swap left buffers */
+ if (fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer &&
+ fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer) {
+ struct gl_renderbuffer *rbTemp;
+ rbTemp = fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer;
+ fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer =
+ fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer;
+ fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer = rbTemp;
+ if (front_left) {
+ struct st_renderbuffer *strb =
+ st_renderbuffer(fb->Attachment[BUFFER_FRONT_LEFT].Renderbuffer);
+ *front_left = strb->surface;
+ }
+ /* mark back buffer contents as undefined */
+ {
+ struct st_renderbuffer *back =
+ st_renderbuffer(fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer);
+ back->defined = GL_FALSE;
+ }
+ }
+ else {
+ /* no front buffer, display the back buffer */
+ if (front_left) {
+ struct st_renderbuffer *strb =
+ st_renderbuffer(fb->Attachment[BUFFER_BACK_LEFT].Renderbuffer);
+ *front_left = strb->surface;
+ }
+ }
+
+ /* swap right buffers (for stereo) */
+ if (fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer &&
+ fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer) {
+ struct gl_renderbuffer *rbTemp;
+ rbTemp = fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer;
+ fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer =
+ fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer;
+ fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer = rbTemp;
+ if (front_right) {
+ struct st_renderbuffer *strb =
+ st_renderbuffer(fb->Attachment[BUFFER_FRONT_RIGHT].Renderbuffer);
+ *front_right = strb->surface;
+ }
+ /* mark back buffer contents as undefined */
+ {
+ struct st_renderbuffer *back =
+ st_renderbuffer(fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer);
+ back->defined = GL_FALSE;
+ }
+ }
+ else {
+ /* no front right buffer, display back right buffer (if exists) */
+ if (front_right) {
+ struct st_renderbuffer *strb =
+ st_renderbuffer(fb->Attachment[BUFFER_BACK_RIGHT].Renderbuffer);
+ *front_right = strb ? strb->surface : NULL;
+ }
+ }
+
+ /* Update the _ColorDrawBuffers[] array and _ColorReadBuffer pointer */
+ _mesa_update_framebuffer(ctx);
+
+ /* Make sure we draw into the new back surface */
+ st_invalidate_state(ctx, _NEW_BUFFERS);