intel / DRI2: Track and flush front-buffer rendering

Track two flags:  whether or not front-buffer rendering is currently
enabled and whether or not front-buffer rendering has been enabled
since the last glFlush.  If the second flag is set, the front-buffer
is flushed via a loader call back.  If the first flag is cleared, the
second flag is cleared at this time.

Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Kristian Høgsberg <krh@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/intel/intel_context.c b/src/mesa/drivers/dri/intel/intel_context.c
index a664e74936..797bfa8c4b 100644
--- a/src/mesa/drivers/dri/intel/intel_context.c
+++ b/src/mesa/drivers/dri/intel/intel_context.c
@@ -391,6 +391,26 @@ intel_flush(GLcontext *ctx, GLboolean needs_mi_flush)
 
    if (intel->batch->map != intel->batch->ptr)
       intel_batchbuffer_flush(intel->batch);
+
+   if ((ctx->DrawBuffer->Name == 0) && intel->front_buffer_dirty) {
+      __DRIscreen *const screen = intel->intelScreen->driScrnPriv;
+
+      if ((screen->dri2.loader->base.version >= 2)
+	  && (screen->dri2.loader->flushFrontBuffer != NULL)) {
+	 (*screen->dri2.loader->flushFrontBuffer)(intel->driDrawable,
+						  intel->driDrawable->loaderPrivate);
+
+	 /* Only clear the dirty bit if front-buffer rendering is no longer
+	  * enabled.  This is done so that the dirty bit can only be set in
+	  * glDrawBuffer.  Otherwise the dirty bit would have to be set at
+	  * each of N places that do rendering.  This has worse performances,
+	  * but it is much easier to get correct.
+	  */
+	 if (intel->is_front_buffer_rendering) {
+	    intel->front_buffer_dirty = GL_FALSE;
+	 }
+      }
+   }
 }
 
 void