[clutter/wip/neil/master-next: 4/5] blur-effect: Use the texture size to work out the x/y step

[Neil Roberts <nroberts src gnome org>]

commit 4d911edbdefea1317741f16264ed319995d86893
Author: Neil Roberts <neil linux intel com>
Date:   Mon Feb 13 15:11:44 2012 +0000

    blur-effect: Use the texture size to work out the x/y step
    
    The blur effect needs to pass a uniform to the GLSL shader so that it
    can know the texture coordinate offset from one texel to another. To
    calculate this the blur effect was previously using the allocation
    size of the actor rounded up to the next power of two. Presumably the
    assumption was that Cogl would round up the size of the texture to the
    next power of two when allocating the texture. However this is not be
    true if the driver supports NPOT textures. Also it doesn't take into
    account the paint volume of the actor which may cause the texture to
    be a completely different size. This patch just changes to directly
    use the size of the texture.

 clutter/clutter-blur-effect.c |   41 +++++++++++++++--------------------------
 1 files changed, 15 insertions(+), 26 deletions(-)
---
diff --git a/clutter/clutter-blur-effect.c b/clutter/clutter-blur-effect.c
index 12b0675..6bf644a 100644
--- a/clutter/clutter-blur-effect.c
+++ b/clutter/clutter-blur-effect.c
@@ -85,12 +85,6 @@ struct _ClutterBlurEffect
   /* a back pointer to our actor, so that we can query it */
   ClutterActor *actor;
 
-  /* the parameters; x_step and y_step depend on
-   * the actor's allocation
-   */
-  gfloat x_step;
-  gfloat y_step;
-
   CoglHandle shader;
   CoglHandle program;
 
@@ -110,17 +104,6 @@ G_DEFINE_TYPE (ClutterBlurEffect,
                clutter_blur_effect,
                CLUTTER_TYPE_OFFSCREEN_EFFECT);
 
-static int
-next_p2 (int a)
-{
-  int rval = 1;
-
-  while (rval < a)
-    rval <<= 1;
-
-  return rval;
-}
-
 static gboolean
 clutter_blur_effect_pre_paint (ClutterEffect *effect)
 {
@@ -151,9 +134,6 @@ clutter_blur_effect_pre_paint (ClutterEffect *effect)
   clutter_actor_get_allocation_box (self->actor, &allocation);
   clutter_actor_box_get_size (&allocation, &width, &height);
 
-  self->x_step = 1.0f / (float) next_p2 (width);
-  self->y_step = 1.0f / (float) next_p2 (height);
-
   if (self->shader == COGL_INVALID_HANDLE)
     {
       self->shader = cogl_create_shader (COGL_SHADER_TYPE_FRAGMENT);
@@ -216,22 +196,31 @@ clutter_blur_effect_paint_target (ClutterOffscreenEffect *effect)
   ClutterBlurEffect *self = CLUTTER_BLUR_EFFECT (effect);
   ClutterOffscreenEffectClass *parent;
   CoglHandle material;
+  CoglHandle texture;
 
   if (self->program == COGL_INVALID_HANDLE)
     goto out;
 
+  texture = clutter_offscreen_effect_get_texture (effect);
+
   if (self->tex_uniform > -1)
     cogl_program_set_uniform_1i (self->program, self->tex_uniform, 0);
 
   if (self->x_step_uniform > -1)
-    cogl_program_set_uniform_1f (self->program,
-                                 self->x_step_uniform,
-                                 self->x_step);
+    {
+      int width = cogl_texture_get_width (texture);
+      cogl_program_set_uniform_1f (self->program,
+                                   self->x_step_uniform,
+                                   1.0f / width);
+    }
 
   if (self->y_step_uniform > -1)
-    cogl_program_set_uniform_1f (self->program,
-                                 self->y_step_uniform,
-                                 self->y_step);
+    {
+      int height = cogl_texture_get_height (texture);
+      cogl_program_set_uniform_1f (self->program,
+                                   self->y_step_uniform,
+                                   1.0f / height);
+    }
 
   material = clutter_offscreen_effect_get_target (effect);
   cogl_material_set_user_program (material, self->program);