pipeline: Avoid reseting texture target for NULL textures

When setting a NULL texture on a CoglPipeline we would also reset the
texture target to a dummy value of 0. Reseting the target also had the
effect of making fragends discard any associated program. In cases where
the NULL texture was only transient until a replacement texture could be
set we were re-running lots of redundant codegen and shader
compilations.

1 files changed, 10 insertions, 6 deletions

diff --git a/cogl/cogl-pipeline.c b/cogl/cogl-pipeline.c
index 6e89c926..e1d5856c 100644
--- a/cogl/cogl-pipeline.c
+++ b/cogl/cogl-pipeline.c
@@ -2393,10 +2393,9 @@ get_texture_target (CoglHandle texture)
   GLuint ignore_handle;
   GLenum gl_target;
 
-  if (texture)
-    cogl_texture_get_gl_texture (texture, &ignore_handle, &gl_target);
-  else
-    return 0;/* XXX: An invalid GL target enum */
+  g_return_val_if_fail (texture, 0);
+
+  cogl_texture_get_gl_texture (texture, &ignore_handle, &gl_target);
 
   return gl_target;
 }
@@ -2419,9 +2418,14 @@ cogl_pipeline_set_layer_texture (CoglPipeline *pipeline,
    * do need to see if they use the same texture targets. Making this
    * distinction is much simpler if they are in different state
    * groups.
+   *
+   * Note: if a NULL texture is set then we leave the target unchanged
+   * so we can avoid needlessly invalidating any associated fragment
+   * program.
    */
-  _cogl_pipeline_set_layer_texture_target (pipeline, layer_index,
-                                           get_texture_target (texture));
+  if (texture)
+    _cogl_pipeline_set_layer_texture_target (pipeline, layer_index,
+                                             get_texture_target (texture));
   _cogl_pipeline_set_layer_texture_data (pipeline, layer_index, texture);
 }