[cogl] Pass the sampler object to snippet hooks on the texture_hookup

[Neil Roberts <nroberts src gnome org>]

commit 6ddf81c8dc35672f098bea179295549c0cabddf6
Author: Neil Roberts <neil linux intel com>
Date:   Fri Feb 10 14:50:02 2012 +0000

    Pass the sampler object to snippet hooks on the texture_hookup
    
    The snippet hook COGL_SNIPPET_HOOK_TEXTURE_LOOKUP now gets passed an
    extra variable called cogl_sampler which is the sampler attached to
    this layer. For example this will be useful when implementing the blur
    effect in Clutter so that it can make the texture hook for that layer
    sample the texture multiple times.
    
    Reviewed-by: Robert Bragg <robert linux intel com>

 cogl/cogl-pipeline-fragend-glsl.c |   37 ++++++++++++++++++++++---------------
 cogl/cogl-snippet.h               |   10 ++++++----
 2 files changed, 28 insertions(+), 19 deletions(-)
---
diff --git a/cogl/cogl-pipeline-fragend-glsl.c b/cogl/cogl-pipeline-fragend-glsl.c
index ccd0da8..c0f2ad1 100644
--- a/cogl/cogl-pipeline-fragend-glsl.c
+++ b/cogl/cogl-pipeline-fragend-glsl.c
@@ -417,12 +417,20 @@ ensure_texture_lookup_generated (CoglPipelineShaderState *shader_state,
 {
   int unit_index = _cogl_pipeline_layer_get_unit_index (layer);
   CoglPipelineSnippetData snippet_data;
+  CoglTextureType texture_type;
+  const char *target_string, *tex_coord_swizzle;
 
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
   if (shader_state->unit_state[unit_index].sampled)
     return;
 
+  texture_type =
+    _cogl_pipeline_layer_get_texture_type (layer);
+  get_texture_target_string (texture_type,
+                             &target_string,
+                             &tex_coord_swizzle);
+
   shader_state->unit_state[unit_index].sampled = TRUE;
 
   g_string_append_printf (shader_state->header,
@@ -430,7 +438,9 @@ ensure_texture_lookup_generated (CoglPipelineShaderState *shader_state,
                           layer->index);
 
   g_string_append_printf (shader_state->source,
-                          "  cogl_texel%i = cogl_texture_lookup%i (",
+                          "  cogl_texel%i = cogl_texture_lookup%i ("
+                          "cogl_sampler%i, ",
+                          layer->index,
                           layer->index,
                           layer->index);
 
@@ -458,28 +468,22 @@ ensure_texture_lookup_generated (CoglPipelineShaderState *shader_state,
      to be replaced */
   if (!has_replace_hook (layer, COGL_SNIPPET_HOOK_TEXTURE_LOOKUP))
     {
-      CoglTextureType texture_type =
-        _cogl_pipeline_layer_get_texture_type (layer);
-      const char *target_string, *tex_coord_swizzle;
-
-      get_texture_target_string (texture_type,
-                                 &target_string,
-                                 &tex_coord_swizzle);
-
       g_string_append_printf (shader_state->header,
                               "vec4\n"
-                              "cogl_real_texture_lookup%i (vec4 coords)\n"
+                              "cogl_real_texture_lookup%i (sampler%s tex,\n"
+                              "                            vec4 coords)\n"
                               "{\n"
                               "  return ",
-                              layer->index);
+                              layer->index,
+                              target_string);
 
       if (G_UNLIKELY (COGL_DEBUG_ENABLED (COGL_DEBUG_DISABLE_TEXTURING)))
         g_string_append (shader_state->header,
                          "vec4 (1.0, 1.0, 1.0, 1.0);\n");
       else
         g_string_append_printf (shader_state->header,
-                                "texture%s (cogl_sampler%i, coords.%s);\n",
-                                target_string, layer->index, tex_coord_swizzle);
+                                "texture%s (tex, coords.%s);\n",
+                                target_string, tex_coord_swizzle);
 
       g_string_append (shader_state->header, "}\n");
     }
@@ -496,8 +500,10 @@ ensure_texture_lookup_generated (CoglPipelineShaderState *shader_state,
                                                   layer->index);
   snippet_data.return_type = "vec4";
   snippet_data.return_variable = "cogl_texel";
-  snippet_data.arguments = "cogl_tex_coord";
-  snippet_data.argument_declarations = "vec4 cogl_tex_coord";
+  snippet_data.arguments = "cogl_sampler, cogl_tex_coord";
+  snippet_data.argument_declarations =
+    g_strdup_printf ("sampler%s cogl_sampler, vec4 cogl_tex_coord",
+                     target_string);
   snippet_data.source_buf = shader_state->header;
 
   _cogl_pipeline_snippet_generate_code (&snippet_data);
@@ -505,6 +511,7 @@ ensure_texture_lookup_generated (CoglPipelineShaderState *shader_state,
   g_free ((char *) snippet_data.chain_function);
   g_free ((char *) snippet_data.final_name);
   g_free ((char *) snippet_data.function_prefix);
+  g_free ((char *) snippet_data.argument_declarations);
 }
 
 static void
diff --git a/cogl/cogl-snippet.h b/cogl/cogl-snippet.h
index cb16883..88a49d2 100644
--- a/cogl/cogl-snippet.h
+++ b/cogl/cogl-snippet.h
@@ -515,11 +515,13 @@ typedef struct _CoglSnippet CoglSnippet;
  * alter the returned texel.
  * </para>
  * <para>
- * Within the snippet code for this hook there are two extra variables
- * available. âcogl_tex_coordâ is a vec4 which contains the texture
- * coordinates that will be used for the texture lookup this can be
+ * Within the snippet code for this hook there are three extra
+ * variables available. âcogl_samplerâ is a sampler object
+ * representing the sampler for the layer where the snippet is
+ * attached. âcogl_tex_coordâ is a vec4 which contains the texture
+ * coordinates that will be used for the texture lookup. This can be
  * modified. âcogl_texelâ will contain the result of the texture
- * lookup. This can be modified.
+ * lookup. This can also be modified.
  * </para>
  * <para>
  * The âdeclarationsâ string in @snippet will be inserted in the