pipeline: Assume blend enabled when there are snippets

Whenever snippets are enabled we can't determine whether the final
color will be fully opaque so we just have to assume blending should
be enabled.

Reviewed-by: Robert Bragg <robert@linux.intel.com>

4 files changed, 43 insertions, 5 deletions

diff --git a/cogl/cogl-pipeline-layer.c b/cogl/cogl-pipeline-layer.c
index 86e07508..76d17e74 100644
--- a/cogl/cogl-pipeline-layer.c
+++ b/cogl/cogl-pipeline-layer.c
@@ -78,6 +78,7 @@ _cogl_pipeline_layer_has_alpha (CoglPipelineLayer *layer)
                                         COGL_PIPELINE_LAYER_STATE_COMBINE);
   CoglPipelineLayerBigState *big_state = combine_authority->big_state;
   CoglPipelineLayer *tex_authority;
+  CoglPipelineLayer *snippets_authority;
 
   /* has_alpha maintains the alpha status for the GL_PREVIOUS layer */
 
@@ -112,6 +113,12 @@ _cogl_pipeline_layer_has_alpha (CoglPipelineLayer *layer)
       return TRUE;
     }
 
+  /* All bets are off if the layer contains any snippets */
+  snippets_authority = _cogl_pipeline_layer_get_authority
+    (layer, COGL_PIPELINE_LAYER_STATE_FRAGMENT_SNIPPETS);
+  if (!COGL_LIST_EMPTY (&snippets_authority->big_state->fragment_snippets))
+    return TRUE;
+
   return FALSE;
 }
 
diff --git a/cogl/cogl-pipeline-state-private.h b/cogl/cogl-pipeline-state-private.h
index 9a38e110..2bc162dc 100644
--- a/cogl/cogl-pipeline-state-private.h
+++ b/cogl/cogl-pipeline-state-private.h
@@ -37,6 +37,12 @@ _cogl_pipeline_has_vertex_snippets (CoglPipeline *pipeline);
 gboolean
 _cogl_pipeline_has_fragment_snippets (CoglPipeline *pipeline);
 
+gboolean
+_cogl_pipeline_has_non_layer_vertex_snippets (CoglPipeline *pipeline);
+
+gboolean
+_cogl_pipeline_has_non_layer_fragment_snippets (CoglPipeline *pipeline);
+
 void
 _cogl_pipeline_set_fog_state (CoglPipeline *pipeline,
                               const CoglPipelineFogState *fog_state);
diff --git a/cogl/cogl-pipeline-state.c b/cogl/cogl-pipeline-state.c
index 04caa918..3477820c 100644
--- a/cogl/cogl-pipeline-state.c
+++ b/cogl/cogl-pipeline-state.c
@@ -1632,7 +1632,7 @@ cogl_pipeline_add_fragment_hook (CoglPipeline *pipeline,
 }
 
 gboolean
-_cogl_pipeline_has_vertex_snippets (CoglPipeline *pipeline)
+_cogl_pipeline_has_non_layer_vertex_snippets (CoglPipeline *pipeline)
 {
   CoglPipeline *authority =
     _cogl_pipeline_get_authority (pipeline,
@@ -1641,6 +1641,22 @@ _cogl_pipeline_has_vertex_snippets (CoglPipeline *pipeline)
   return !COGL_LIST_EMPTY (&authority->big_state->vertex_snippets);
 }
 
+gboolean
+_cogl_pipeline_has_vertex_snippets (CoglPipeline *pipeline)
+{
+  return _cogl_pipeline_has_non_layer_vertex_snippets (pipeline);
+}
+
+gboolean
+_cogl_pipeline_has_non_layer_fragment_snippets (CoglPipeline *pipeline)
+{
+  CoglPipeline *authority =
+    _cogl_pipeline_get_authority (pipeline,
+                                  COGL_PIPELINE_STATE_FRAGMENT_SNIPPETS);
+
+  return !COGL_LIST_EMPTY (&authority->big_state->fragment_snippets);
+}
+
 static gboolean
 check_layer_has_fragment_snippet (CoglPipelineLayer *layer,
                                   void *user_data)
@@ -1662,12 +1678,9 @@ check_layer_has_fragment_snippet (CoglPipelineLayer *layer,
 gboolean
 _cogl_pipeline_has_fragment_snippets (CoglPipeline *pipeline)
 {
-  CoglPipeline *authority =
-    _cogl_pipeline_get_authority (pipeline,
-                                  COGL_PIPELINE_STATE_FRAGMENT_SNIPPETS);
   gboolean found_fragment_snippet = FALSE;
 
-  if (!COGL_LIST_EMPTY (&authority->big_state->fragment_snippets))
+  if (_cogl_pipeline_has_non_layer_fragment_snippets (pipeline))
     return TRUE;
 
   _cogl_pipeline_foreach_layer_internal (pipeline,
diff --git a/cogl/cogl-pipeline.c b/cogl/cogl-pipeline.c
index 2831b55f..026c9c65 100644
--- a/cogl/cogl-pipeline.c
+++ b/cogl/cogl-pipeline.c
@@ -761,6 +761,18 @@ _cogl_pipeline_needs_blending_enabled (CoglPipeline    *pipeline,
         return TRUE;
     }
 
+  if (changes & COGL_PIPELINE_STATE_FRAGMENT_SNIPPETS)
+    {
+      if (!_cogl_pipeline_has_non_layer_fragment_snippets (pipeline))
+        return TRUE;
+    }
+
+  if (changes & COGL_PIPELINE_STATE_VERTEX_SNIPPETS)
+    {
+      if (!_cogl_pipeline_has_non_layer_vertex_snippets (pipeline))
+        return TRUE;
+    }
+
   /* XXX: we should only need to look at these if lighting is enabled
    */
   if (changes & COGL_PIPELINE_STATE_LIGHTING)