Method
CoglPipelineset_layer_combine
Declaration [src]
gboolean
cogl_pipeline_set_layer_combine (
  CoglPipeline* pipeline,
  int layer_index,
  const char* blend_string,
  GError** error
)
Description [src]
These are all the functions available for texture combining:
- REPLACE(arg0) = arg0
- MODULATE(arg0, arg1) = arg0 x arg1
- ADD(arg0, arg1) = arg0 + arg1
- ADD_SIGNED(arg0, arg1) = arg0 + arg1 - 0.5
- INTERPOLATE(arg0, arg1, arg2) = arg0 x arg2 + arg1 x (1 - arg2)
- 
SUBTRACT(arg0, arg1) = arg0 - arg1
 DOT3_RGB(arg0, arg1) = 4 x ((arg0[R] - 0.5)) * (arg1[R] - 0.5) +
                             (arg0[G] - 0.5)) * (arg1[G] - 0.5) +
                             (arg0[B] - 0.5)) * (arg1[B] - 0.5))
-
 DOT3_RGBA(arg0, arg1) = 4 x ((arg0[R] - 0.5)) * (arg1[R] - 0.5) +
                              (arg0[G] - 0.5)) * (arg1[G] - 0.5) +
                              (arg0[B] - 0.5)) * (arg1[B] - 0.5))
The valid source names for texture combining are:
- TEXTURE: Use the color from the current texture layer
- TEXTURE_0, TEXTURE_1, etc: Use the color from the specified texture layer
- CONSTANT: Use the color from the constant given with- cogl_pipeline_set_layer_combine_constant()
- PRIMARY: Use the color of the pipeline as set with- cogl_pipeline_set_color()
- PREVIOUS: Either use the texture color from the previous layer, or if this is layer 0, use the color of the pipeline as set with- cogl_pipeline_set_color()
Layer Combine Examples:
This is effectively what the default blending is:
RGBA = MODULATE (PREVIOUS, TEXTURE)
This could be used to cross-fade between two images, using
the alpha component of a constant as the interpolator. The constant
color is given by calling cogl_pipeline_set_layer_combine_constant().
RGBA = INTERPOLATE (PREVIOUS, TEXTURE, CONSTANT[A])
You can’t give a multiplication factor for arguments as you can with blending.
Parameters
- layer_index
- 
            Type: intSpecifies the layer you want define a combine function for. 
- blend_string
- 
            Type: const char*A Cogl blend string describing the desired texture combine function. The data is owned by the caller of the method. The value is a NUL terminated UTF-8 string. 
- error
- 
            Type: GError **The return location for a recoverable error. The argument can be NULL.If the return location is not NULL, then you must initialize it to aNULLGError*.The argument will be left initialized to NULLby the method if there are no errors.In case of error, the argument will be set to a newly allocated GError; the caller will take ownership of the data, and be responsible for freeing it.