## Pipeline

Pipeline — Functions for creating and manipulating the GPU pipeline

## Synopsis

    CoglPipeline *      cogl_pipeline_new                   (void);
    CoglPipeline *      cogl_pipeline_copy                  (CoglPipeline *source);
    gboolean            cogl_is_pipeline                    (CoglHandle handle);
    void                cogl_pipeline_set_color             (CoglPipeline *pipeline,
                                                             const CoglColor *color);
    void                cogl_pipeline_set_color4ub          (CoglPipeline *pipeline,
                                                             guint8 red,
                                                             guint8 green,
                                                             guint8 blue,
                                                             guint8 alpha);
    void                cogl_pipeline_set_color4f           (CoglPipeline *pipeline,
                                                             float red,
                                                             float green,
                                                             float blue,
                                                             float alpha);
    void                cogl_pipeline_get_color             (CoglPipeline *pipeline,
                                                             CoglColor *color);
    void                cogl_pipeline_set_ambient           (CoglPipeline *pipeline,
                                                             const CoglColor *ambient);
    void                cogl_pipeline_get_ambient           (CoglPipeline *pipeline,
                                                             CoglColor *ambient);
    void                cogl_pipeline_set_diffuse           (CoglPipeline *pipeline,
                                                             const CoglColor *diffuse);
    void                cogl_pipeline_get_diffuse           (CoglPipeline *pipeline,
                                                             CoglColor *diffuse);
    void                cogl_pipeline_set_ambient_and_diffuse
                                                            (CoglPipeline *pipeline,
                                                             const CoglColor *color);
    void                cogl_pipeline_set_emission          (CoglPipeline *pipeline,
                                                             const CoglColor *emission);
    void                cogl_pipeline_get_emission          (CoglPipeline *pipeline,
                                                             CoglColor *emission);
    void                cogl_pipeline_set_specular          (CoglPipeline *pipeline,
                                                             const CoglColor *specular);
    void                cogl_pipeline_get_specular          (CoglPipeline *pipeline,
                                                             CoglColor *specular);
    void                cogl_pipeline_set_shininess         (CoglPipeline *pipeline,
                                                             float shininess);
    float               cogl_pipeline_get_shininess         (CoglPipeline *pipeline);
    void                cogl_pipeline_set_alpha_test_function
                                                            (CoglPipeline *pipeline,
                                                             CoglPipelineAlphaFunc alpha_func,
                                                             float alpha_reference);
    #define             COGL_BLEND_STRING_ERROR
    enum                CoglBlendStringError;
    gboolean            cogl_pipeline_set_blend             (CoglPipeline *pipeline,
                                                             const char *blend_string,
                                                             GError **error);
    void                cogl_pipeline_set_blend_constant    (CoglPipeline *pipeline,
                                                             const CoglColor *constant_color);
    void                cogl_pipeline_set_point_size        (CoglHandle pipeline,
                                                             float point_size);
    float               cogl_pipeline_get_point_size        (CoglHandle pipeline);
    void                cogl_pipeline_set_layer_texture     (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglHandle texture);
    void                cogl_pipeline_set_layer_filters     (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineFilter min_filter,
                                                             CoglPipelineFilter mag_filter);
    void                cogl_pipeline_set_layer_wrap_mode   (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);
    void                cogl_pipeline_set_layer_wrap_mode_s (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);
    void                cogl_pipeline_set_layer_wrap_mode_t (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);
    void                cogl_pipeline_set_layer_wrap_mode_p (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);
    gboolean            cogl_pipeline_set_layer_combine     (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             const char *blend_string,
                                                             GError **error);
    void                cogl_pipeline_set_layer_combine_constant
                                                            (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             const CoglColor *constant);
    void                cogl_pipeline_set_layer_matrix      (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             const CoglMatrix *matrix);
    gboolean            cogl_pipeline_set_layer_point_sprite_coords_enabled
                                                            (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             gboolean enable,
                                                             GError **error);
    gboolean            cogl_pipeline_get_layer_point_sprite_coords_enabled
                                                            (CoglPipeline *pipeline,
                                                             int layer_index);
    void                cogl_pipeline_remove_layer          (CoglPipeline *pipeline,
                                                             int layer_index);
    int                 cogl_pipeline_get_n_layers          (CoglPipeline *pipeline);
    void                cogl_pipeline_foreach_layer         (CoglPipeline *pipeline,
                                                             CoglPipelineLayerCallback callback,
                                                             void *user_data);

## Description

Cogl allows creating and manipulating objects representing the full configuration of the GPU pipeline. In simplified terms the GPU pipeline takes primitive geometry as the input, it first performs vertex processing, allowing you to deform your geometry, then rasterizes that (turning it from pure geometry into fragments) then performs fragment processing including depth testing and texture mapping. Finally it blends the result with the framebuffer.

## Details

### cogl_pipeline_new ()

    CoglPipeline *      cogl_pipeline_new                   (void);

Allocates and initializes a default simple pipeline that will color a primitive white.

Returns : | a pointer to a new CoglPipeline

### cogl_pipeline_copy ()

    CoglPipeline *      cogl_pipeline_copy                  (CoglPipeline *source);

Creates a new pipeline with the configuration copied from the source pipeline.

We would strongly advise developers to always aim to use `cogl_pipeline_copy()` instead of `cogl_pipeline_new()` whenever there will be any similarity between two pipelines. Copying a pipeline helps Cogl keep track of a pipelines ancestry which we may use to help minimize GPU state changes.

`source` : | a CoglPipeline object to copy
Returns : | a pointer to the newly allocated CoglPipeline

Since 2.0

### cogl_is_pipeline ()

    gboolean            cogl_is_pipeline                    (CoglHandle handle);

Gets whether the given handle references an existing pipeline object.

`handle` : | A CoglHandle
Returns : | `TRUE` if the handle references a CoglPipeline, `FALSE` otherwise

### cogl_pipeline_set_color ()

    void                cogl_pipeline_set_color             (CoglPipeline *pipeline,
                                                             const CoglColor *color);

Sets the basic color of the pipeline, used when no lighting is enabled.

Note that if you don't add any layers to the pipeline then the color will be blended unmodified with the destination; the default blend expects premultiplied colors: for example, use (0.5, 0.0, 0.0, 0.5) for semi-transparent red. See `cogl_color_premultiply()`.

The default value is (1.0, 1.0, 1.0, 1.0)

`pipeline` : | A CoglPipeline object
`color` : | The components of the color

Since 2.0

### cogl_pipeline_set_color4ub ()

    void                cogl_pipeline_set_color4ub          (CoglPipeline *pipeline,
                                                             guint8 red,
                                                             guint8 green,
                                                             guint8 blue,
                                                             guint8 alpha);

Sets the basic color of the pipeline, used when no lighting is enabled.

The default value is (0xff, 0xff, 0xff, 0xff)

`pipeline` : | A CoglPipeline object
`red` : | The red component
`green` : | The green component
`blue` : | The blue component
`alpha` : | The alpha component

Since 2.0

### cogl_pipeline_set_color4f ()

    void                cogl_pipeline_set_color4f           (CoglPipeline *pipeline,
                                                             float red,
                                                             float green,
                                                             float blue,
                                                             float alpha);

Sets the basic color of the pipeline, used when no lighting is enabled.

The default value is (1.0, 1.0, 1.0, 1.0)

`pipeline` : | A CoglPipeline object
`red` : | The red component
`green` : | The green component
`blue` : | The blue component
`alpha` : | The alpha component

Since 2.0

### cogl_pipeline_get_color ()

    void                cogl_pipeline_get_color             (CoglPipeline *pipeline,
                                                             CoglColor *color);

Retrieves the current pipeline color.

`pipeline` : | A CoglPipeline object
`color` : | The location to store the color. [out]

Since 2.0

### cogl_pipeline_set_ambient ()

    void                cogl_pipeline_set_ambient           (CoglPipeline *pipeline,
                                                             const CoglColor *ambient);

Sets the pipeline's ambient color, in the standard OpenGL lighting model. The ambient color affects the overall color of the object.

Since the diffuse color will be intense when the light hits the surface directly, the ambient will be most apparent where the light hits at a slant.

The default value is (0.2, 0.2, 0.2, 1.0)

`pipeline` : | A CoglPipeline object
`ambient` : | The components of the desired ambient color

Since 2.0

### cogl_pipeline_get_ambient ()

    void                cogl_pipeline_get_ambient           (CoglPipeline *pipeline,
                                                             CoglColor *ambient);

Retrieves the current ambient color for `pipeline`

`pipeline` : | A CoglPipeline object
`ambient` : | The location to store the ambient color

Since 2.0

### cogl_pipeline_set_diffuse ()

    void                cogl_pipeline_set_diffuse           (CoglPipeline *pipeline,
                                                             const CoglColor *diffuse);

Sets the pipeline's diffuse color, in the standard OpenGL lighting model. The diffuse color is most intense where the light hits the surface directly - perpendicular to the surface.

The default value is (0.8, 0.8, 0.8, 1.0)

`pipeline` : | A CoglPipeline object
`diffuse` : | The components of the desired diffuse color

Since 2.0

### cogl_pipeline_get_diffuse ()

    void                cogl_pipeline_get_diffuse           (CoglPipeline *pipeline,
                                                             CoglColor *diffuse);

Retrieves the current diffuse color for `pipeline`

`pipeline` : | A CoglPipeline object
`diffuse` : | The location to store the diffuse color

Since 2.0

### cogl_pipeline_set_ambient_and_diffuse ()

    void                cogl_pipeline_set_ambient_and_diffuse
                                                            (CoglPipeline *pipeline,
                                                             const CoglColor *color);

Conveniently sets the diffuse and ambient color of `pipeline` at the same time. See `cogl_pipeline_set_ambient()` and `cogl_pipeline_set_diffuse()`.

The default ambient color is (0.2, 0.2, 0.2, 1.0)

The default diffuse color is (0.8, 0.8, 0.8, 1.0)

`pipeline` : | A CoglPipeline object
`color` : | The components of the desired ambient and diffuse colors

Since 2.0

### cogl_pipeline_set_emission ()

    void                cogl_pipeline_set_emission          (CoglPipeline *pipeline,
                                                             const CoglColor *emission);

Sets the pipeline's emissive color, in the standard OpenGL lighting model. It will look like the surface is a light source emitting this color.

The default value is (0.0, 0.0, 0.0, 1.0)

`pipeline` : | A CoglPipeline object
`emission` : | The components of the desired emissive color

Since 2.0

### cogl_pipeline_get_emission ()

    void                cogl_pipeline_get_emission          (CoglPipeline *pipeline,
                                                             CoglColor *emission);

Retrieves the pipelines current emission color.

`pipeline` : | A CoglPipeline object
`emission` : | The location to store the emission color

Since 2.0

### cogl_pipeline_set_specular ()

    void                cogl_pipeline_set_specular          (CoglPipeline *pipeline,
                                                             const CoglColor *specular);

Sets the pipeline's specular color, in the standard OpenGL lighting model. The intensity of the specular color depends on the viewport position, and is brightest along the lines of reflection.

The default value is (0.0, 0.0, 0.0, 1.0)

`pipeline` : | A CoglPipeline object
`specular` : | The components of the desired specular color

Since 2.0

### cogl_pipeline_get_specular ()

    void                cogl_pipeline_get_specular          (CoglPipeline *pipeline,
                                                             CoglColor *specular);

Retrieves the pipelines current specular color.

`pipeline` : | A CoglPipeline object
`specular` : | The location to store the specular color

Since 2.0

### cogl_pipeline_set_shininess ()

    void                cogl_pipeline_set_shininess         (CoglPipeline *pipeline,
                                                             float shininess);

Sets the shininess of the pipeline, in the standard OpenGL lighting model, which determines the size of the specular highlights. A higher `shininess` will produce smaller highlights which makes the object appear more shiny.

The default value is 0.0

`pipeline` : | A CoglPipeline object
`shininess` : | The desired shininess; must be >= 0.0

Since 2.0

### cogl_pipeline_get_shininess ()

    float               cogl_pipeline_get_shininess         (CoglPipeline *pipeline);

Retrieves the pipelines current emission color.

`pipeline` : | A CoglPipeline object
Returns : | The pipelines current shininess value

Since 2.0

### cogl_pipeline_set_alpha_test_function ()

    void                cogl_pipeline_set_alpha_test_function
                                                            (CoglPipeline *pipeline,
                                                             CoglPipelineAlphaFunc alpha_func,
                                                             float alpha_reference);

Before a primitive is blended with the framebuffer, it goes through an alpha test stage which lets you discard fragments based on the current alpha value. This function lets you change the function used to evaluate the alpha channel, and thus determine which fragments are discarded and which continue on to the blending stage.

The default is `COGL_PIPELINE_ALPHA_FUNC_ALWAYS`

`pipeline` : | A CoglPipeline object
`alpha_func` : | A `CoglPipelineAlphaFunc` constant
`alpha_reference` : | A reference point that the chosen alpha function uses to compare incoming fragments to.

Since 2.0

### COGL_BLEND_STRING_ERROR

    #define COGL_BLEND_STRING_ERROR (cogl_blend_string_error_quark ())

GError domain for blend string parser errors

Since 1.0

### enum CoglBlendStringError

    typedef enum { /*< prefix=COGL_BLEND_STRING_ERROR >*/
      COGL_BLEND_STRING_ERROR_PARSE_ERROR,
      COGL_BLEND_STRING_ERROR_ARGUMENT_PARSE_ERROR,
      COGL_BLEND_STRING_ERROR_INVALID_ERROR,
      COGL_BLEND_STRING_ERROR_GPU_UNSUPPORTED_ERROR
    } CoglBlendStringError;

Error enumeration for the blend strings parser

`COGL_BLEND_STRING_ERROR_PARSE_ERROR` | Generic parse error
`COGL_BLEND_STRING_ERROR_ARGUMENT_PARSE_ERROR` | Argument parse error
`COGL_BLEND_STRING_ERROR_INVALID_ERROR` | Internal parser error
`COGL_BLEND_STRING_ERROR_GPU_UNSUPPORTED_ERROR` | Blend string not supported by the GPU

Since 1.0

### cogl_pipeline_set_blend ()

    gboolean            cogl_pipeline_set_blend             (CoglPipeline *pipeline,
                                                             const char *blend_string,
                                                             GError **error);

If not already familiar; please refer here for an overview of what blend strings are, and their syntax.

Blending occurs after the alpha test function, and combines fragments with the framebuffer.

Currently the only blend function Cogl exposes is `ADD()`. So any valid blend statements will be of the form:

    1

    <channel-mask>=ADD(SRC_COLOR*(<factor>), DST_COLOR*(<factor>))

### Warning

The brackets around blend factors are currently not optional!

This is the list of source-names usable as blend factors:

- SRC_COLOR: The color of the in comming fragment

- DST_COLOR: The color of the framebuffer

- CONSTANT: The constant set via `cogl_pipeline_set_blend_constant()`

The source names can be used according to the color-source and factor syntax, so for example "(1-SRC_COLOR[A])" would be a valid factor, as would "(CONSTANT[RGB])"

These can also be used as factors:

- 0: (0, 0, 0, 0)
- 1: (1, 1, 1, 1)
- SRC_ALPHA_SATURATE_FACTOR: (f,f,f,1) where f = MIN(SRC_COLOR[A],1-DST_COLOR[A])

### Note

Remember; all color components are normalized to the range [0, 1] before computing the result of blending.

Example 1. Blend Strings/1

Blend a non-premultiplied source over a destination with premultiplied alpha:

    "RGB = ADD(SRC_COLOR*(SRC_COLOR[A]), DST_COLOR*(1-SRC_COLOR[A]))"
    "A   = ADD(SRC_COLOR, DST_COLOR*(1-SRC_COLOR[A]))"

Example 2. Blend Strings/2

Blend a premultiplied source over a destination with premultiplied alpha

    "RGBA = ADD(SRC_COLOR, DST_COLOR*(1-SRC_COLOR[A]))"

The default blend string is:

    1

    RGBA = ADD (SRC_COLOR, DST_COLOR*(1-SRC_COLOR[A]))

That gives normal alpha-blending when the calculated color for the pipeline is in premultiplied form.

`pipeline` : | A CoglPipeline object
`blend_string` : | A Cogl blend string describing the desired blend function.
`error` : | return location for a GError that may report lack of driver support if you give separate blend string statements for the alpha channel and RGB channels since some drivers, or backends such as GLES 1.1, don't support this feature. May be `NULL`, in which case a warning will be printed out using GLib's logging facilities if an error is encountered.
Returns : | `TRUE` if the blend string was successfully parsed, and the described blending is supported by the underlying driver/hardware. If there was an error, `FALSE` is returned and `error` is set accordingly (if present).

Since 2.0

### cogl_pipeline_set_blend_constant ()

    void                cogl_pipeline_set_blend_constant    (CoglPipeline *pipeline,
                                                             const CoglColor *constant_color);

When blending is setup to reference a CONSTANT blend factor then blending will depend on the constant set with this function.

`pipeline` : | A CoglPipeline object
`constant_color` : | The constant color you want

Since 2.0

### cogl_pipeline_set_point_size ()

    void                cogl_pipeline_set_point_size        (CoglHandle pipeline,
                                                             float point_size);

Changes the size of points drawn when `COGL_VERTICES_MODE_POINTS` is used with the vertex buffer API. Note that typically the GPU will only support a limited minimum and maximum range of point sizes. If the chosen point size is outside that range then the nearest value within that range will be used instead. The size of a point is in screen space so it will be the same regardless of any transformations. The default point size is 1.0.

`pipeline` : | a CoglHandle to a pipeline.
`point_size` : | the new point size.

Since 2.0

### cogl_pipeline_get_point_size ()

    float               cogl_pipeline_get_point_size        (CoglHandle pipeline);

Get the size of points drawn when `COGL_VERTICES_MODE_POINTS` is used with the vertex buffer API.

`pipeline` : | a CoglHandle to a pipeline.
Returns : | the point size of the pipeline.

Since 2.0

### cogl_pipeline_set_layer_texture ()

    void                cogl_pipeline_set_layer_texture     (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglHandle texture);

### cogl_pipeline_set_layer_filters ()

    void                cogl_pipeline_set_layer_filters     (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineFilter min_filter,
                                                             CoglPipelineFilter mag_filter);

Changes the decimation and interpolation filters used when a texture is drawn at other scales than 100%.

`pipeline` : | A CoglPipeline object
`layer_index` : | the layer number to change.
`min_filter` : | the filter used when scaling a texture down.
`mag_filter` : | the filter used when magnifying a texture.

### cogl_pipeline_set_layer_wrap_mode ()

    void                cogl_pipeline_set_layer_wrap_mode   (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);

Sets the wrap mode for all three coordinates of texture lookups on this layer. This is equivalent to calling `cogl_pipeline_set_layer_wrap_mode_s()`, `cogl_pipeline_set_layer_wrap_mode_t()` and `cogl_pipeline_set_layer_wrap_mode_p()` separately.

`pipeline` : | A CoglPipeline object
`layer_index` : | the layer number to change.
`mode` : | the new wrap mode

Since 2.0

### cogl_pipeline_set_layer_wrap_mode_s ()

    void                cogl_pipeline_set_layer_wrap_mode_s (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);

Sets the wrap mode for the 's' coordinate of texture lookups on this layer.

`pipeline` : | A CoglPipeline object
`layer_index` : | the layer number to change.
`mode` : | the new wrap mode

Since 2.0

### cogl_pipeline_set_layer_wrap_mode_t ()

    void                cogl_pipeline_set_layer_wrap_mode_t (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);

Sets the wrap mode for the 't' coordinate of texture lookups on this layer.

`pipeline` : | A CoglPipeline object
`layer_index` : | the layer number to change.
`mode` : | the new wrap mode

Since 2.0

### cogl_pipeline_set_layer_wrap_mode_p ()

    void                cogl_pipeline_set_layer_wrap_mode_p (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             CoglPipelineWrapMode mode);

Sets the wrap mode for the 'p' coordinate of texture lookups on this layer. 'p' is the third coordinate.

`pipeline` : | A CoglPipeline object
`layer_index` : | the layer number to change.
`mode` : | the new wrap mode

Since 2.0

### cogl_pipeline_set_layer_combine ()

    gboolean            cogl_pipeline_set_layer_combine     (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             const char *blend_string,
                                                             GError **error);

If not already familiar; you can refer here for an overview of what blend strings are and there syntax.

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))

Refer to the color-source syntax for describing the arguments. 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_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:

    1

    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_constant.

    1

    RGBA = INTERPOLATE (PREVIOUS, TEXTURE, CONSTANT[A])

### Note

You can't give a multiplication factor for arguments as you can with blending.

`pipeline` : | A CoglPipeline object
`layer_index` : | Specifies the layer you want define a combine function for
`blend_string` : | A Cogl blend string describing the desired texture combine function.
`error` : | A GError that may report parse errors or lack of GPU/driver support. May be `NULL`, in which case a warning will be printed out if an error is encountered.
Returns : | `TRUE` if the blend string was successfully parsed, and the described texture combining is supported by the underlying driver and or hardware. On failure, `FALSE` is returned and `error` is set

Since 2.0

### cogl_pipeline_set_layer_combine_constant ()

    void                cogl_pipeline_set_layer_combine_constant
                                                            (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             const CoglColor *constant);

When you are using the 'CONSTANT' color source in a layer combine description then you can use this function to define its value.

`pipeline` : | A CoglPipeline object
`layer_index` : | Specifies the layer you want to specify a constant used for texture combining
`constant` : | The constant color you want

Since 2.0

### cogl_pipeline_set_layer_matrix ()

    void                cogl_pipeline_set_layer_matrix      (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             const CoglMatrix *matrix);

This function lets you set a matrix that can be used to e.g. translate and rotate a single layer of a pipeline used to fill your geometry.

`pipeline` : | A CoglPipeline object
`layer_index` : | the index for the layer inside `pipeline`
`matrix` : | the transformation matrix for the layer

### cogl_pipeline_set_layer_point_sprite_coords_enabled ()

    gboolean            cogl_pipeline_set_layer_point_sprite_coords_enabled
                                                            (CoglPipeline *pipeline,
                                                             int layer_index,
                                                             gboolean enable,
                                                             GError **error);

When rendering points, if `enable` is `TRUE` then the texture coordinates for this layer will be replaced with coordinates that vary from 0.0 to 1.0 across the primitive. The top left of the point will have the coordinates 0.0,0.0 and the bottom right will have 1.0,1.0. If `enable` is `FALSE` then the coordinates will be fixed for the entire point.

This function will only work if `COGL_FEATURE_POINT_SPRITE` is available. If the feature is not available then the function will return `FALSE` and set `error`.

`pipeline` : | a CoglHandle to a pipeline.
`layer_index` : | the layer number to change.
`enable` : | whether to enable point sprite coord generation.
`error` : | A return location for a GError, or NULL to ignore errors.
Returns : | `TRUE` if the function succeeds, `FALSE` otherwise.

Since 2.0

### cogl_pipeline_get_layer_point_sprite_coords_enabled ()

    gboolean            cogl_pipeline_get_layer_point_sprite_coords_enabled
                                                            (CoglPipeline *pipeline,
                                                             int layer_index);

Gets whether point sprite coordinate generation is enabled for this texture layer.

`pipeline` : | a CoglHandle to a pipeline.
`layer_index` : | the layer number to check.
Returns : | whether the texture coordinates will be replaced with point sprite coordinates.

Since 2.0

### cogl_pipeline_remove_layer ()

    void                cogl_pipeline_remove_layer          (CoglPipeline *pipeline,
                                                             int layer_index);

This function removes a layer from your pipeline

`pipeline` : | A CoglPipeline object
`layer_index` : | Specifies the layer you want to remove

### cogl_pipeline_get_n_layers ()

    int                 cogl_pipeline_get_n_layers          (CoglPipeline *pipeline);

Retrieves the number of layers defined for the given `pipeline`

`pipeline` : | A CoglPipeline object
Returns : | the number of layers

Since 2.0

### cogl_pipeline_foreach_layer ()

    void                cogl_pipeline_foreach_layer         (CoglPipeline *pipeline,
                                                             CoglPipelineLayerCallback callback,
                                                             void *user_data);

Iterates all the layer indices of the given `pipeline`.

`pipeline` : | A CoglPipeline object
`callback` : | A CoglPipelineLayerCallback to be called for each layer index
`user_data` : | Private data that will be passed to the callback

Since 2.0

Stability Level: Unstable