[cogl-material] Some improvements for how we sync CoglMaterial state with OpenGL

This flattens the three functions: cogl_material_flush_gl_material_state,
.._flush_gl_alpha_func and .._flush_gl_blend_func into one:
cogl_flush_material_gl_state which doesn't takes a material handle. (the handle
is instead taken from the context.)

This has allows us to avoid re-submitting some state to OpenGL when the
material has not been replaced.

Note: Avoiding redundant state changes for material layers isn't dealt with
in this patch.

cogl-material.h

@@ -152,20 +152,6 @@ void cogl_material_set_shininess (CoglHandle material,
 void cogl_material_set_emission (CoglHandle       material,
 				 const CoglColor *emission);
 
-/**
- * cogl_set_source:
- * @material: A CoglMaterial object
- *
- * This function sets the source material that will be used to fill
- * subsequent geometry emitted via the cogl API.
- *
- * XXX: This doesn't really belong to the cogl-material API, it should
- * move to cogl.h
- *
- * Since 1.0
- */
-void cogl_set_source (CoglHandle material);
-
 /**
  * CoglMaterialAlphaFunc:
  * @COGL_MATERIAL_ALPHA_FUNC_NEVER: Never let the fragment through.
@@ -586,34 +572,10 @@ void cogl_material_set_layer_matrix (CoglHandle  material,
  * Note: This API is hopfully just a stop-gap solution. Ideally
  * cogl_enable will be replaced.
  */
+/* TODO: find a nicer solution! */
 gulong
 cogl_material_get_cogl_enable_flags (CoglHandle handle);
 
-/**
- * cogl_material_flush_gl_material_state:
- * @material: A CoglMaterial object
- *
- * This commits the glMaterial state to the OpenGL driver. Normally you
- * shouldn't need to use this function directly, since Cogl will do this
- * internally, but if you are developing custom primitives directly with
- * OpenGL you may want to use this.
- */
-void cogl_material_flush_gl_material_state (CoglHandle material_handle);
-
-/**
- * cogl_material_flush_gl_alpha_func:
- * @material: A CoglMaterial object
- *
- */
-void cogl_material_flush_gl_alpha_func (CoglHandle material_handle);
-
-/**
- * cogl_material_flush_gl_blend_func:
- * @material: A CoglMaterial object
- *
- */
-void cogl_material_flush_gl_blend_func (CoglHandle material_handle);
-
 /**
  * cogl_material_get_layers:
  * @material: A CoglMaterial object
@@ -691,6 +653,38 @@ CoglHandle cogl_material_layer_get_texture (CoglHandle layer_handle);
  */
 void cogl_material_layer_flush_gl_sampler_state (CoglHandle layer_handle);
 
+/**
+ * cogl_set_source:
+ * @material: A CoglMaterial object
+ *
+ * This function sets the source material that will be used to fill
+ * subsequent geometry emitted via the cogl API.
+ *
+ * Note: in the future we may add the ability to set a front facing
+ * material, and a back facing material, in which case this function
+ * will set both to the same.
+ *
+ * Since 1.0
+ */
+/* XXX: This doesn't really belong to the cogl-material API, it should
+ * move to cogl.h */
+void cogl_set_source (CoglHandle material);
+
+/**
+ * cogl_flush_material_gl_state:
+ *
+ * This function commits all the state of the source CoglMaterial - not
+ * including the per-layer state - to the OpenGL[ES] driver.
+ *
+ * Normally you shouldn't need to use this function directly, but if you
+ * are developing a custom primitive using raw OpenGL that works with
+ * CoglMaterials, then you may want to use this function.
+ *
+ * Since 1.0
+ */
+/* XXX: This should be moved with cogl_set_source to cogl.h */
+void cogl_flush_material_gl_state (void);
+
 G_END_DECLS
 
 #endif /* __COGL_MATERIAL_H__ */

common/cogl-material.c

@@ -79,7 +79,8 @@ cogl_material_set_ambient (CoglHandle handle,
   ambient[1] = cogl_color_get_green_float (ambient_color);
   ambient[2] = cogl_color_get_blue_float (ambient_color);
   ambient[3] = cogl_color_get_alpha_float (ambient_color);
-  /* material->ambient = *ambient_color; */
+
+  material->flags |= COGL_MATERIAL_FLAG_DIRTY;
 }
 
 void
@@ -98,7 +99,8 @@ cogl_material_set_diffuse (CoglHandle handle,
   diffuse[1] = cogl_color_get_green_float (diffuse_color);
   diffuse[2] = cogl_color_get_blue_float (diffuse_color);
   diffuse[3] = cogl_color_get_alpha_float (diffuse_color);
-  /* material->diffuse = *diffuse_color; */
+
+  material->flags |= COGL_MATERIAL_FLAG_DIRTY;
 }
 
 void
@@ -125,7 +127,8 @@ cogl_material_set_specular (CoglHandle handle,
   specular[1] = cogl_color_get_green_float (specular_color);
   specular[2] = cogl_color_get_blue_float (specular_color);
   specular[3] = cogl_color_get_alpha_float (specular_color);
-  /* material->specular = *specular_color; */
+
+  material->flags |= COGL_MATERIAL_FLAG_DIRTY;
 }
 
 void
@@ -143,6 +146,8 @@ cogl_material_set_shininess (CoglHandle handle,
   material = _cogl_material_pointer_from_handle (handle);
 
   material->shininess = (GLfloat)shininess * 128.0;
+
+  material->flags |= COGL_MATERIAL_FLAG_DIRTY;
 }
 
 void
@@ -161,22 +166,8 @@ cogl_material_set_emission (CoglHandle handle,
   emission[1] = cogl_color_get_green_float (emission_color);
   emission[2] = cogl_color_get_blue_float (emission_color);
   emission[3] = cogl_color_get_alpha_float (emission_color);
-  /* material->emission = *emission_color; */
-}
 
-/* TODO: Should go in cogl.c */
+  material->flags |= COGL_MATERIAL_FLAG_DIRTY;
-void
-cogl_set_source (CoglHandle material_handle)
-{
-  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
-
-  g_return_if_fail (cogl_is_material (material_handle));
-
-  if (ctx->source_material)
-    cogl_material_unref (ctx->source_material);
-
-  cogl_material_ref (material_handle);
-  ctx->source_material = material_handle;
 }
 
 void
@@ -191,6 +182,8 @@ cogl_material_set_alpha_test_function (CoglHandle handle,
   material = _cogl_material_pointer_from_handle (handle);
   material->alpha_func = alpha_func;
   material->alpha_func_reference = (GLfloat)alpha_reference;
+
+  material->flags |= COGL_MATERIAL_FLAG_DIRTY;
 }
 
 void
@@ -205,6 +198,8 @@ cogl_material_set_blend_factors (CoglHandle handle,
   material = _cogl_material_pointer_from_handle (handle);
   material->blend_src_factor = src_factor;
   material->blend_dst_factor = dst_factor;
+
+  material->flags |= COGL_MATERIAL_FLAG_DIRTY;
 }
 
 /* Asserts that a layer corresponding to the given index exists. If no
@@ -492,44 +487,6 @@ cogl_material_get_cogl_enable_flags (CoglHandle material_handle)
   return enable_flags;
 }
 
-void
-cogl_material_flush_gl_material_state (CoglHandle material_handle)
-{
-  CoglMaterial	*material;
-
-  g_return_if_fail (cogl_is_material (material_handle));
-
-  material = _cogl_material_pointer_from_handle (material_handle);
-
-  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_AMBIENT, material->ambient));
-  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, material->diffuse));
-  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, material->specular));
-  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_EMISSION, material->emission));
-  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_SHININESS, &material->shininess));
-}
-
-void
-cogl_material_flush_gl_alpha_func (CoglHandle material_handle)
-{
-  CoglMaterial	*material;
-
-  g_return_if_fail (cogl_is_material (material_handle));
-
-  material = _cogl_material_pointer_from_handle (material_handle);
-
-  /* NB: Currently the Cogl defines are compatible with the GL ones: */
-  GE (glAlphaFunc (material->alpha_func, material->alpha_func_reference));
-}
-
-void
-cogl_material_flush_gl_blend_func (CoglHandle material_handle)
-{
-  CoglMaterial	*material;
-
-  g_return_if_fail (cogl_is_material (material_handle));
-  GE (glBlendFunc (material->blend_src_factor, material->blend_dst_factor));
-}
-
 /* It's a bit out of the ordinary to return a const GList *, but it's
  * probably sensible to try and avoid list manipulation for every
  * primitive emitted in a scene, every frame.
@@ -678,3 +635,50 @@ cogl_material_layer_flush_gl_sampler_state (CoglHandle layer_handle)
     }
 }
 
+/* TODO: Should go in cogl.c, but that implies duplication which is also
+ * not ideal. */
+void
+cogl_set_source (CoglHandle material_handle)
+{
+  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
+
+  g_return_if_fail (cogl_is_material (material_handle));
+
+  if (ctx->source_material == material_handle)
+    return;
+
+  if (ctx->source_material)
+    cogl_material_unref (ctx->source_material);
+
+  cogl_material_ref (material_handle);
+  ctx->source_material = material_handle;
+}
+/* TODO: add cogl_set_front_source (), and cogl_set_back_source () */
+
+void
+cogl_flush_material_gl_state (void)
+{
+  CoglMaterial *material;
+  _COGL_GET_CONTEXT (ctx, NO_RETVAL);
+
+  material = _cogl_material_pointer_from_handle (ctx->source_material);
+
+  if (ctx->source_material == ctx->current_material
+      && !(material->flags & COGL_MATERIAL_FLAG_DIRTY))
+    return;
+
+  /* FIXME - we only need to set these if lighting is enabled... */
+  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_AMBIENT, material->ambient));
+  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, material->diffuse));
+  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_SPECULAR, material->specular));
+  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_EMISSION, material->emission));
+  GE (glMaterialfv (GL_FRONT_AND_BACK, GL_SHININESS, &material->shininess));
+
+  /* NB: Currently the Cogl defines are compatible with the GL ones: */
+  GE (glAlphaFunc (material->alpha_func, material->alpha_func_reference));
+
+  GE (glBlendFunc (material->blend_src_factor, material->blend_dst_factor));
+
+  ctx->current_material = ctx->source_material;
+}
+

gl/cogl-context.c

@@ -62,6 +62,7 @@ cogl_create_context ()
   _context->material_handles = NULL;
   _context->material_layer_handles = NULL;
   _context->source_material = NULL;
+  _context->current_material = NULL;
 
   _context->fbo_handles = NULL;
   _context->draw_buffer = COGL_WINDOW_BUFFER;

gl/cogl-context.h

@@ -70,6 +70,7 @@ typedef struct
   GArray           *material_handles;
   GArray           *material_layer_handles;
   CoglHandle	    source_material;
+  CoglHandle	    current_material;
 
   /* Framebuffer objects */
   GArray           *fbo_handles;

gl/cogl-texture.c

@@ -2531,9 +2531,8 @@ cogl_material_rectangle (CoglFixed   x1,
   GE( glVertexPointer (2, GL_FLOAT, 0, quad_coords));
 
   /* Setup the remaining GL state according to this material... */
-  cogl_material_flush_gl_material_state (material);
+  cogl_flush_material_gl_state ();
-  cogl_material_flush_gl_alpha_func (material);
+
-  cogl_material_flush_gl_blend_func (material);
   /* FIXME: This api is a bit yukky, ideally it will be removed if we
    * re-work the cogl_enable mechanism */
   enable_flags |= cogl_material_get_cogl_enable_flags (material);