cogl: Add a GLSL 'progend'

'progend' is short for 'program backend'. The progend is intended to
operate on combined state from a fragment backend and a vertex
backend. The progend has an 'end' function which is run whenever the
pipeline is flushed and the two pipeline change notification
functions. All of the progends are run whenever the pipeline is
flushed instead of selecting a single one because it is possible that
multiple progends may be in use for example if the vertends and
fragends are different. The GLSL progend will take the shaders
generated by the fragend and vertend and link them into a single
program. The fragend code has been changed to only generate the shader
and not the program. The idea is that pipelines can share fragment
shader objects even if their vertex state is different. The authority
for the progend needs to be the combined authority on the vertend and
fragend state.

clutter/cogl/cogl/Makefile.am

@@ -240,6 +240,8 @@ cogl_sources_c = \
 	$(srcdir)/cogl-pipeline-fragend-arbfp-private.h	\
 	$(srcdir)/cogl-pipeline-fragend-fixed.c		\
 	$(srcdir)/cogl-pipeline-fragend-fixed-private.h	\
+	$(srcdir)/cogl-pipeline-progend-glsl.c		\
+	$(srcdir)/cogl-pipeline-progend-glsl-private.h	\
 	$(srcdir)/cogl-material-compat.c		\
 	$(srcdir)/cogl-program.c			\
 	$(srcdir)/cogl-program-private.h		\

clutter/cogl/cogl/cogl-pipeline-fragend-glsl-private.h

@@ -32,5 +32,8 @@
 
 extern const CoglPipelineFragend _cogl_pipeline_glsl_fragend;
 
+GLuint
+_cogl_pipeline_fragend_glsl_get_shader (CoglPipeline *pipeline);
+
 #endif /* __COGL_PIPELINE_FRAGEND_GLSL_PRIVATE_H */
 

clutter/cogl/cogl/cogl-pipeline-opengl.c

@@ -1094,6 +1094,11 @@ _cogl_pipeline_flush_gl_state (CoglPipeline *pipeline,
   if (G_UNLIKELY (i >= G_N_ELEMENTS (_cogl_pipeline_fragends)))
     g_warning ("No usable pipeline fragment backend was found!");
 
+  for (i = 0; i < COGL_PIPELINE_N_PROGENDS; i++)
+    if (_cogl_pipeline_progends[i]->end)
+      _cogl_pipeline_progends[i]->end (pipeline, pipelines_difference,
+                                       n_tex_coord_attribs);
+
   /* FIXME: This reference is actually resulting in lots of
    * copy-on-write reparenting because one-shot pipelines end up
    * living for longer than necessary and so any later modification of

clutter/cogl/cogl/cogl-pipeline-private.h

@@ -71,6 +71,20 @@ typedef struct _CoglPipelineLayer     CoglPipelineLayer;
 #define COGL_PIPELINE_FRAGEND_DEFAULT    0
 #define COGL_PIPELINE_FRAGEND_UNDEFINED  3
 
+/* If we have either of the GLSL backends then we also need a GLSL
+   progend to combine the shaders generated into a single
+   program. Currently there is only one progend but if we ever add
+   other languages they would likely need their own progend too. The
+   progends are different from the other backends because there can be
+   more than one in use for each pipeline. All of the progends are
+   invoked whenever a pipeline is flushed. */
+#ifdef COGL_PIPELINE_FRAGEND_GLSL
+#define COGL_PIPELINE_PROGEND_GLSL       0
+#define COGL_PIPELINE_N_PROGENDS         1
+#else
+#define COGL_PIPELINE_N_PROGENDS         0
+#endif
+
 /* XXX: should I rename these as
  * COGL_PIPELINE_LAYER_STATE_INDEX_XYZ... ?
  */
@@ -660,6 +674,19 @@ typedef struct _CoglPipelineFragend
   void (*free_priv) (CoglPipeline *pipeline);
 } CoglPipelineFragend;
 
+typedef struct
+{
+  void (*end) (CoglPipeline *pipeline,
+               unsigned long pipelines_difference,
+               int n_tex_coord_attribs);
+  void (*pipeline_pre_change_notify) (CoglPipeline *pipeline,
+                                      CoglPipelineState change,
+                                      const CoglColor *new_color);
+  void (*layer_pre_change_notify) (CoglPipeline *owner,
+                                   CoglPipelineLayer *layer,
+                                   CoglPipelineLayerState change);
+} CoglPipelineProgend;
+
 typedef enum
 {
   COGL_PIPELINE_PROGRAM_TYPE_GLSL = 1,
@@ -669,6 +696,8 @@ typedef enum
 
 extern const CoglPipelineFragend *
 _cogl_pipeline_fragends[COGL_PIPELINE_N_FRAGENDS];
+extern const CoglPipelineProgend *
+_cogl_pipeline_progends[];
 
 void
 _cogl_pipeline_init_default_pipeline (void);

clutter/cogl/cogl/cogl-pipeline-progend-glsl-private.h

@@ -0,0 +1,36 @@
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2010 Intel Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ *
+ *
+ * Authors:
+ *   Neil Roberts <neil@linux.intel.com>
+ */
+
+#ifndef __COGL_PIPELINE_PROGEND_GLSL_PRIVATE_H
+#define __COGL_PIPELINE_PROGEND_GLSL_PRIVATE_H
+
+#include "cogl-pipeline-private.h"
+
+extern const CoglPipelineProgend _cogl_pipeline_glsl_progend;
+
+#endif /* __COGL_PIPELINE_PROGEND_GLSL_PRIVATE_H */
+

clutter/cogl/cogl/cogl-pipeline-progend-glsl.c

@@ -0,0 +1,542 @@
+/*
+ * Cogl
+ *
+ * An object oriented GL/GLES Abstraction/Utility Layer
+ *
+ * Copyright (C) 2010 Intel Corporation.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ *
+ *
+ * Authors:
+ *   Neil Roberts <neil@linux.intel.com>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "cogl-pipeline-private.h"
+#include "cogl-pipeline-opengl-private.h"
+
+#ifdef COGL_PIPELINE_PROGEND_GLSL
+
+#include "cogl.h"
+#include "cogl-internal.h"
+#include "cogl-context.h"
+#include "cogl-handle.h"
+#include "cogl-program-private.h"
+#include "cogl-pipeline-fragend-glsl-private.h"
+
+#ifndef HAVE_COGL_GLES2
+
+#define glCreateProgram      ctx->drv.pf_glCreateProgram
+#define glAttachShader       ctx->drv.pf_glAttachShader
+#define glUseProgram         ctx->drv.pf_glUseProgram
+#define glLinkProgram        ctx->drv.pf_glLinkProgram
+#define glDeleteProgram      ctx->drv.pf_glDeleteProgram
+#define glGetProgramInfoLog  ctx->drv.pf_glGetProgramInfoLog
+#define glGetProgramiv       ctx->drv.pf_glGetProgramiv
+#define glGetUniformLocation ctx->drv.pf_glGetUniformLocation
+#define glUniform1i          ctx->drv.pf_glUniform1i
+#define glUniform1f          ctx->drv.pf_glUniform1f
+#define glUniform4fv         ctx->drv.pf_glUniform4fv
+
+#endif /* HAVE_COGL_GLES2 */
+
+const CoglPipelineProgend _cogl_pipeline_glsl_progend;
+
+typedef struct _UnitState
+{
+  unsigned int dirty_combine_constant:1;
+
+  GLint combine_constant_uniform;
+} UnitState;
+
+typedef struct
+{
+  unsigned int ref_count;
+
+  /* Age that the user program had last time we generated a GL
+     program. If it's different then we need to relink the program */
+  unsigned int user_program_age;
+
+  GLuint program;
+
+  /* To allow writing shaders that are portable between GLES 2 and
+   * OpenGL Cogl prepends a number of boilerplate #defines and
+   * declarations to user shaders. One of those declarations is an
+   * array of texture coordinate varyings, but to know how to emit the
+   * declaration we need to know how many texture coordinate
+   * attributes are in use.  The boilerplate also needs to be changed
+   * if this increases. */
+  int n_tex_coord_attribs;
+
+#ifdef HAVE_COGL_GLES2
+  /* The GLES2 generated program that was generated from the user
+     program. This is used to detect when the GLES2 backend generates
+     a different program which would mean we need to flush all of the
+     custom uniforms. This is a massive hack but it can go away once
+     this GLSL backend starts generating its own shaders */
+  GLuint gles2_program;
+
+  /* Under GLES2 the alpha test is implemented in the shader. We need
+     a uniform for the reference value */
+  gboolean dirty_alpha_test_reference;
+  GLint alpha_test_reference_uniform;
+#endif
+
+  /* We need to track the last pipeline that the program was used with
+   * so know if we need to update all of the uniforms */
+  CoglPipeline *last_used_for_pipeline;
+
+  UnitState *unit_state;
+} CoglPipelineProgendPrivate;
+
+static CoglUserDataKey glsl_priv_key;
+
+static void
+delete_program (GLuint program)
+{
+#ifdef HAVE_COGL_GLES2
+  /* This hack can go away once this GLSL backend replaces the GLES2
+     wrapper */
+  _cogl_gles2_clear_cache_for_program (program);
+#else
+  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
+#endif
+
+  GE (glDeleteProgram (program));
+}
+
+static CoglPipelineProgendPrivate *
+get_glsl_priv (CoglPipeline *pipeline)
+{
+  return cogl_object_get_user_data (COGL_OBJECT (pipeline), &glsl_priv_key);
+}
+
+static void
+destroy_glsl_priv (void *user_data)
+{
+  CoglPipelineProgendPrivate *priv = user_data;
+
+  if (--priv->ref_count == 0)
+    {
+      if (priv->program)
+        delete_program (priv->program);
+
+      g_free (priv->unit_state);
+
+      g_slice_free (CoglPipelineProgendPrivate, priv);
+    }
+}
+
+static void
+set_glsl_priv (CoglPipeline *pipeline, CoglPipelineProgendPrivate *priv)
+{
+  cogl_object_set_user_data (COGL_OBJECT (pipeline),
+                             &glsl_priv_key,
+                             priv,
+                             destroy_glsl_priv);
+}
+
+static void
+dirty_glsl_program_state (CoglPipeline *pipeline)
+{
+  cogl_object_set_user_data (COGL_OBJECT (pipeline),
+                             &glsl_priv_key,
+                             NULL,
+                             destroy_glsl_priv);
+}
+
+static void
+link_program (GLint gl_program)
+{
+  /* On GLES2 we'll let the backend link the program. This hack can go
+     away once this backend replaces the GLES2 wrapper */
+#ifndef HAVE_COGL_GLES2
+
+  GLint link_status;
+
+  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
+
+  GE( glLinkProgram (gl_program) );
+
+  GE( glGetProgramiv (gl_program, GL_LINK_STATUS, &link_status) );
+
+  if (!link_status)
+    {
+      GLint log_length;
+      GLsizei out_log_length;
+      char *log;
+
+      GE( glGetProgramiv (gl_program, GL_INFO_LOG_LENGTH, &log_length) );
+
+      log = g_malloc (log_length);
+
+      GE( glGetProgramInfoLog (gl_program, log_length,
+                               &out_log_length, log) );
+
+      g_warning ("Failed to link GLSL program:\n%.*s\n",
+                 log_length, log);
+
+      g_free (log);
+    }
+
+#endif /* HAVE_COGL_GLES2 */
+}
+
+typedef struct
+{
+  int unit;
+  GLuint gl_program;
+  gboolean update_all;
+  CoglPipelineProgendPrivate *priv;
+} UpdateUniformsState;
+
+static gboolean
+get_uniform_cb (CoglPipeline *pipeline,
+                int layer_index,
+                void *user_data)
+{
+  UpdateUniformsState *state = user_data;
+  CoglPipelineProgendPrivate *priv = state->priv;
+  UnitState *unit_state = &priv->unit_state[state->unit];
+  GLint uniform_location;
+
+  _COGL_GET_CONTEXT (ctx, FALSE);
+
+  /* We can reuse the source buffer to create the uniform name because
+     the program has now been linked */
+  g_string_set_size (ctx->fragment_source_buffer, 0);
+  g_string_append_printf (ctx->fragment_source_buffer,
+                          "_cogl_sampler_%i", state->unit);
+
+  GE_RET( uniform_location,
+          glGetUniformLocation (state->gl_program,
+                                ctx->fragment_source_buffer->str) );
+
+  /* We can set the uniform immediately because the samplers are the
+     unit index not the texture object number so it will never
+     change. Unfortunately GL won't let us use a constant instead of a
+     uniform */
+  if (uniform_location != -1)
+    GE( glUniform1i (uniform_location, state->unit) );
+
+  g_string_set_size (ctx->fragment_source_buffer, 0);
+  g_string_append_printf (ctx->fragment_source_buffer,
+                          "_cogl_layer_constant_%i", state->unit);
+
+  GE_RET( uniform_location,
+          glGetUniformLocation (state->gl_program,
+                                ctx->fragment_source_buffer->str) );
+
+  unit_state->combine_constant_uniform = uniform_location;
+
+  state->unit++;
+
+  return TRUE;
+}
+
+static gboolean
+update_constants_cb (CoglPipeline *pipeline,
+                     int layer_index,
+                     void *user_data)
+{
+  UpdateUniformsState *state = user_data;
+  CoglPipelineProgendPrivate *priv = state->priv;
+  UnitState *unit_state = &priv->unit_state[state->unit++];
+
+  _COGL_GET_CONTEXT (ctx, FALSE);
+
+  if (unit_state->combine_constant_uniform != -1 &&
+      (state->update_all || unit_state->dirty_combine_constant))
+    {
+      float constant[4];
+      _cogl_pipeline_get_layer_combine_constant (pipeline,
+                                                 layer_index,
+                                                 constant);
+      GE (glUniform4fv (unit_state->combine_constant_uniform,
+                        1, constant));
+      unit_state->dirty_combine_constant = FALSE;
+    }
+  return TRUE;
+}
+
+#ifdef HAVE_COGL_GLES2
+
+static void
+update_alpha_test_reference (CoglPipeline *pipeline,
+                             GLuint gl_program,
+                             CoglPipelineProgendPrivate *priv)
+{
+  float alpha_reference;
+
+  if (priv->dirty_alpha_test_reference &&
+      priv->alpha_test_reference_uniform != -1)
+    {
+      alpha_reference = cogl_pipeline_get_alpha_test_reference (pipeline);
+
+      GE( glUniform1f (priv->alpha_test_reference_uniform,
+                       alpha_reference) );
+
+      priv->dirty_alpha_test_reference = FALSE;
+    }
+}
+
+#endif /* HAVE_COGL_GLES2 */
+
+static void
+_cogl_pipeline_progend_glsl_end (CoglPipeline *pipeline,
+                                 unsigned long pipelines_difference,
+                                 int n_tex_coord_attribs)
+{
+  CoglPipelineProgendPrivate *priv;
+  GLuint gl_program;
+  gboolean program_changed = FALSE;
+  UpdateUniformsState state;
+  CoglProgram *user_program;
+
+  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
+
+  /* If neither of the glsl fragend or vertends are used then we don't
+     need to do anything */
+  if (pipeline->fragend != COGL_PIPELINE_FRAGEND_GLSL)
+    return;
+
+  priv = get_glsl_priv (pipeline);
+
+  user_program = cogl_pipeline_get_user_program (pipeline);
+
+  if (priv == NULL)
+    {
+      CoglPipeline *authority;
+
+      /* Get the authority for anything affecting program state. This
+         should include both fragment codegen state and vertex codegen
+         state */
+      authority = _cogl_pipeline_find_equivalent_parent
+        (pipeline,
+         COGL_PIPELINE_STATE_AFFECTS_FRAGMENT_CODEGEN &
+         ~COGL_PIPELINE_STATE_LAYERS,
+         COGL_PIPELINE_LAYER_STATE_AFFECTS_FRAGMENT_CODEGEN,
+         COGL_PIPELINE_FIND_EQUIVALENT_COMPARE_TEXTURE_TARGET);
+
+      priv = get_glsl_priv (authority);
+
+      if (priv == NULL)
+        {
+          priv = g_slice_new (CoglPipelineProgendPrivate);
+          priv->ref_count = 1;
+          priv->program = 0;
+          priv->n_tex_coord_attribs = 0;
+          priv->unit_state = g_new (UnitState,
+                                    cogl_pipeline_get_n_layers (pipeline));
+#ifdef HAVE_COGL_GLES2
+          priv->gles2_program = 0;
+#endif
+          set_glsl_priv (authority, priv);
+        }
+
+      if (authority != pipeline)
+        {
+          priv->ref_count++;
+          set_glsl_priv (pipeline, priv);
+        }
+    }
+
+  /* If the program has changed since the last link then we do
+   * need to relink
+   *
+   * Also if the number of texture coordinate attributes in use has
+   * increased, then delete the program so we can prepend a new
+   * _cogl_tex_coord[] varying array declaration. */
+  if (priv->program && user_program &&
+      (user_program->age != priv->user_program_age ||
+       n_tex_coord_attribs > priv->n_tex_coord_attribs))
+    {
+      delete_program (priv->program);
+      priv->program = 0;
+    }
+
+  if (priv->program == 0)
+    {
+      GLuint backend_shader;
+      GSList *l;
+
+      GE_RET( priv->program, glCreateProgram () );
+
+      /* Attach all of the shader from the user program */
+      if (user_program)
+        {
+          if (priv->n_tex_coord_attribs > n_tex_coord_attribs)
+            n_tex_coord_attribs = priv->n_tex_coord_attribs;
+
+#ifdef HAVE_COGL_GLES2
+          /* Find the largest count of texture coordinate attributes
+           * associated with each of the shaders so we can ensure a consistent
+           * _cogl_tex_coord[] array declaration across all of the shaders.*/
+          if (user_program)
+            for (l = user_program->attached_shaders; l; l = l->next)
+              {
+                CoglShader *shader = l->data;
+                n_tex_coord_attribs = MAX (shader->n_tex_coord_attribs,
+                                           n_tex_coord_attribs);
+              }
+#endif
+
+          for (l = user_program->attached_shaders; l; l = l->next)
+            {
+              CoglShader *shader = l->data;
+
+              _cogl_shader_compile_real (shader, n_tex_coord_attribs);
+
+              g_assert (shader->language == COGL_SHADER_LANGUAGE_GLSL);
+
+              GE( glAttachShader (priv->program,
+                                  shader->gl_handle) );
+            }
+
+          priv->user_program_age = user_program->age;
+        }
+
+      /* Attach any shaders from the GLSL backends */
+      if (pipeline->fragend == COGL_PIPELINE_FRAGEND_GLSL &&
+          (backend_shader = _cogl_pipeline_fragend_glsl_get_shader (pipeline)))
+        GE( glAttachShader (priv->program, backend_shader) );
+
+      link_program (priv->program);
+
+      program_changed = TRUE;
+
+      priv->n_tex_coord_attribs = n_tex_coord_attribs;
+    }
+
+  gl_program = priv->program;
+
+#ifdef HAVE_COGL_GLES2
+  /* This function is a massive hack to get the GLES2 backend to
+     work. It should only be neccessary until we move the GLSL vertex
+     shader generation into a vertend instead of the GLES2 driver
+     backend */
+  gl_program = _cogl_gles2_use_program (gl_program);
+  /* We need to detect when the GLES2 backend gives us a different
+     program from last time */
+  if (gl_program != priv->gles2_program)
+    {
+      priv->gles2_program = gl_program;
+      program_changed = TRUE;
+    }
+#else
+  _cogl_use_program (gl_program, COGL_PIPELINE_PROGRAM_TYPE_GLSL);
+#endif
+
+  state.unit = 0;
+  state.gl_program = gl_program;
+  state.priv = priv;
+
+  if (program_changed)
+    cogl_pipeline_foreach_layer (pipeline,
+                                 get_uniform_cb,
+                                 &state);
+
+  state.unit = 0;
+  state.update_all = (program_changed ||
+                      priv->last_used_for_pipeline != pipeline);
+
+  cogl_pipeline_foreach_layer (pipeline,
+                               update_constants_cb,
+                               &state);
+
+#ifdef HAVE_COGL_GLES2
+  if (program_changed)
+    GE_RET( priv->alpha_test_reference_uniform,
+            glGetUniformLocation (gl_program,
+                                  "_cogl_alpha_test_ref") );
+  if (program_changed ||
+      priv->last_used_for_pipeline != pipeline)
+    priv->dirty_alpha_test_reference = TRUE;
+
+  update_alpha_test_reference (pipeline, gl_program, priv);
+#endif
+
+  if (user_program)
+    _cogl_program_flush_uniforms (user_program,
+                                  gl_program,
+                                  program_changed);
+
+  /* We need to track the last pipeline that the program was used with
+   * so know if we need to update all of the uniforms */
+  priv->last_used_for_pipeline = pipeline;
+}
+
+static void
+_cogl_pipeline_progend_glsl_pre_change_notify (CoglPipeline *pipeline,
+                                               CoglPipelineState change,
+                                               const CoglColor *new_color)
+{
+  if ((change & COGL_PIPELINE_STATE_AFFECTS_FRAGMENT_CODEGEN))
+    dirty_glsl_program_state (pipeline);
+#ifdef COGL_HAS_GLES2
+  else if ((change & COGL_PIPELINE_STATE_ALPHA_FUNC_REFERENCE))
+    {
+      CoglPipelineProgendPrivate *priv = get_glsl_priv (pipeline);
+      if (priv)
+        priv->dirty_alpha_test_reference = TRUE;
+    }
+#endif
+}
+
+/* NB: layers are considered immutable once they have any dependants
+ * so although multiple pipelines can end up depending on a single
+ * static layer, we can guarantee that if a layer is being *changed*
+ * then it can only have one pipeline depending on it.
+ *
+ * XXX: Don't forget this is *pre* change, we can't read the new value
+ * yet!
+ */
+static void
+_cogl_pipeline_progend_glsl_layer_pre_change_notify (
+                                                CoglPipeline *owner,
+                                                CoglPipelineLayer *layer,
+                                                CoglPipelineLayerState change)
+{
+  if ((change & COGL_PIPELINE_LAYER_STATE_AFFECTS_FRAGMENT_CODEGEN))
+    {
+      dirty_glsl_program_state (owner);
+      return;
+    }
+
+  if (change & COGL_PIPELINE_LAYER_STATE_COMBINE_CONSTANT)
+    {
+      CoglPipelineProgendPrivate *priv = get_glsl_priv (owner);
+      if (priv)
+        {
+          int unit_index = _cogl_pipeline_layer_get_unit_index (layer);
+          priv->unit_state[unit_index].dirty_combine_constant = TRUE;
+        }
+    }
+}
+
+const CoglPipelineProgend _cogl_pipeline_glsl_progend =
+  {
+    _cogl_pipeline_progend_glsl_end,
+    _cogl_pipeline_progend_glsl_pre_change_notify,
+    _cogl_pipeline_progend_glsl_layer_pre_change_notify
+  };
+
+#endif /* COGL_PIPELINE_PROGEND_GLSL */
+

clutter/cogl/cogl/cogl-pipeline.c

@@ -64,6 +64,10 @@ static void recursively_free_layer_caches (CoglPipeline *pipeline);
 static gboolean _cogl_pipeline_is_weak (CoglPipeline *pipeline);
 
 const CoglPipelineFragend *_cogl_pipeline_fragends[COGL_PIPELINE_N_FRAGENDS];
+/* The 'MAX' here is so that we don't define an empty array when there
+   are no progends */
+const CoglPipelineProgend *
+_cogl_pipeline_progends[MAX (COGL_PIPELINE_N_PROGENDS, 1)];
 
 #ifdef COGL_PIPELINE_FRAGEND_GLSL
 #include "cogl-pipeline-fragend-glsl-private.h"
@@ -74,6 +78,9 @@ const CoglPipelineFragend *_cogl_pipeline_fragends[COGL_PIPELINE_N_FRAGENDS];
 #ifdef COGL_PIPELINE_FRAGEND_FIXED
 #include "cogl-pipeline-fragend-fixed-private.h"
 #endif
+#ifdef COGL_PIPELINE_PROGEND_GLSL
+#include "cogl-pipeline-progend-glsl-private.h"
+#endif
 
 COGL_OBJECT_DEFINE (Pipeline, pipeline);
 /* This type was made deprecated before the cogl_is_pipeline_layer
@@ -199,7 +206,7 @@ _cogl_pipeline_init_default_pipeline (void)
 
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
-  /* Take this opportunity to setup the fragment processing backends... */
+  /* Take this opportunity to setup the backends... */
 #ifdef COGL_PIPELINE_FRAGEND_GLSL
   _cogl_pipeline_fragends[COGL_PIPELINE_FRAGEND_GLSL] =
     &_cogl_pipeline_glsl_fragend;
@@ -212,6 +219,10 @@ _cogl_pipeline_init_default_pipeline (void)
   _cogl_pipeline_fragends[COGL_PIPELINE_FRAGEND_FIXED] =
     &_cogl_pipeline_fixed_fragend;
 #endif
+#ifdef COGL_PIPELINE_PROGEND_GLSL
+  _cogl_pipeline_progends[COGL_PIPELINE_PROGEND_GLSL] =
+    &_cogl_pipeline_glsl_progend;
+#endif
 
   _cogl_pipeline_node_init (COGL_PIPELINE_NODE (pipeline));
 
@@ -1129,6 +1140,7 @@ _cogl_pipeline_pre_change_notify (CoglPipeline     *pipeline,
                                   gboolean          from_layer_change)
 {
   CoglPipeline *authority;
+  int i;
 
   _COGL_GET_CONTEXT (ctx, NO_RETVAL);
 
@@ -1201,6 +1213,14 @@ _cogl_pipeline_pre_change_notify (CoglPipeline     *pipeline,
         fragend->pipeline_pre_change_notify (pipeline, change, new_color);
     }
 
+  /* Notify all of the progends */
+  if (!from_layer_change)
+    for (i = 0; i < COGL_PIPELINE_N_PROGENDS; i++)
+      if (_cogl_pipeline_progends[i]->pipeline_pre_change_notify)
+        _cogl_pipeline_progends[i]->pipeline_pre_change_notify (pipeline,
+                                                                change,
+                                                                new_color);
+
   /* There may be an arbitrary tree of descendants of this pipeline;
    * any of which may indirectly depend on this pipeline as the
    * authority for some set of properties. (Meaning for example that
@@ -1504,6 +1524,22 @@ _cogl_pipeline_fragend_layer_change_notify (CoglPipeline *owner,
     }
 }
 
+static void
+_cogl_pipeline_progend_layer_change_notify (CoglPipeline *owner,
+                                            CoglPipelineLayer *layer,
+                                            CoglPipelineLayerState change)
+{
+  int i;
+
+  /* Give all of the progends a chance to notice that the layer has
+     changed */
+  for (i = 0; i < COGL_PIPELINE_N_PROGENDS; i++)
+    if (_cogl_pipeline_progends[i]->layer_pre_change_notify)
+      _cogl_pipeline_progends[i]->layer_pre_change_notify (owner,
+                                                           layer,
+                                                           change);
+}
+
 unsigned int
 _cogl_get_n_args_for_combine_func (GLint func)
 {
@@ -1661,6 +1697,7 @@ _cogl_pipeline_layer_pre_change_notify (CoglPipeline *required_owner,
    * dependant on this layer so it's ok to modify it. */
 
   _cogl_pipeline_fragend_layer_change_notify (required_owner, layer, change);
+  _cogl_pipeline_progend_layer_change_notify (required_owner, layer, change);
 
   /* If the layer being changed is the same as the last layer we
    * flushed to the corresponding texture unit then we keep a track of