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e007bc5358
mutter/cogl/cogl-material.h
Neil Roberts e007bc5358 cogl-material: Add support for setting the wrap mode for a layer 
Previously, Cogl's texture coordinate system was effectively always
GL_REPEAT so that if an application specifies coordinates outside the
range 0→1 it would get repeated copies of the texture. It would
however change the mode to GL_CLAMP_TO_EDGE if all of the coordinates
are in the range 0→1 so that in the common case that the whole texture
is being drawn with linear filtering it will not blend in edge pixels
from the opposite sides.

This patch adds the option for applications to change the wrap mode
per layer. There are now three wrap modes: 'repeat', 'clamp-to-edge'
and 'automatic'. The automatic map mode is the default and it
implements the previous behaviour. The wrap mode can be changed for
the s and t coordinates independently. I've tried to make the
internals support setting the r coordinate but as we don't support 3D
textures yet I haven't exposed any public API for it.

The texture backends still have a set_wrap_mode virtual but this value
is intended to be transitory and it will be changed whenever the
material is flushed (although the backends are expected to cache it so
that it won't use too many GL calls). In my understanding this value
was always meant to be transitory and all primitives were meant to set
the value before drawing. However there were comments suggesting that
this is not the expected behaviour. In particular the vertex buffer
drawing code never set a wrap mode so it would end up with whatever
the texture was previously used for. These issues are now fixed
because the material will always set the wrap modes.

There is code to manually implement clamp-to-edge for textures that
can't be hardware repeated. However this doesn't fully work because it
relies on being able to draw the stretched parts using quads with the
same values for tx1 and tx2. The texture iteration code doesn't
support this so it breaks. This is a separate bug and it isn't
trivially solved.

When flushing a material there are now extra options to set wrap mode
overrides. The overrides are an array of values for each layer that
specifies an override for the s, t or r coordinates. The primitives
use this to implement the automatic wrap mode. cogl_polygon also uses
it to set GL_CLAMP_TO_BORDER mode for its trick to render sliced
textures. Although this code has been added it looks like the sliced
trick has been broken for a while and I haven't attempted to fix it
here.

I've added a constant to represent the maximum number of layers that a
material supports so that I can size the overrides array. I've set it
to 32 because as far as I can tell we have that limit imposed anyway
because the other flush options use a guint32 to store a flag about
each layer. The overrides array ends up adding 32 bytes to each flush
options struct which may be a concern.

http://bugzilla.openedhand.com/show_bug.cgi?id=2063
2010-04-12 15:44:23 +01:00

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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2007,2008,2009 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/>.
*
*
*/
#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif
#ifndef __COGL_MATERIAL_H__
#define __COGL_MATERIAL_H__
G_BEGIN_DECLS
#include <cogl/cogl-types.h>
#include <cogl/cogl-matrix.h>
/**
* SECTION:cogl-material
* @short_description: Fuctions for creating and manipulating materials
*
* COGL allows creating and manipulating materials used to fill in
* geometry. Materials may simply be lighting attributes (such as an
* ambient and diffuse colour) or might represent one or more textures
* blended together.
*/
/**
* CoglMaterialFilter:
* @COGL_MATERIAL_FILTER_NEAREST: Measuring in manhatten distance from the,
* current pixel center, use the nearest texture texel
* @COGL_MATERIAL_FILTER_LINEAR: Use the weighted average of the 4 texels
* nearest the current pixel center
* @COGL_MATERIAL_FILTER_NEAREST_MIPMAP_NEAREST: Select the mimap level whose
* texel size most closely matches the current pixel, and use the
* %COGL_MATERIAL_FILTER_NEAREST criterion
* @COGL_MATERIAL_FILTER_LINEAR_MIPMAP_NEAREST: Select the mimap level whose
* texel size most closely matches the current pixel, and use the
* %COGL_MATERIAL_FILTER_LINEAR criterion
* @COGL_MATERIAL_FILTER_NEAREST_MIPMAP_LINEAR: Select the two mimap levels
* whose texel size most closely matches the current pixel, use
* the %COGL_MATERIAL_FILTER_NEAREST criterion on each one and take
* their weighted average
* @COGL_MATERIAL_FILTER_LINEAR_MIPMAP_LINEAR: Select the two mimap levels
* whose texel size most closely matches the current pixel, use
* the %COGL_MATERIAL_FILTER_LINEAR criterion on each one and take
* their weighted average
*
* Texture filtering is used whenever the current pixel maps either to more
* than one texture element (texel) or less than one. These filter enums
* correspond to different strategies used to come up with a pixel color, by
* possibly referring to multiple neighbouring texels and taking a weighted
* average or simply using the nearest texel.
*/
typedef enum {
COGL_MATERIAL_FILTER_NEAREST = GL_NEAREST,
COGL_MATERIAL_FILTER_LINEAR = GL_LINEAR,
COGL_MATERIAL_FILTER_NEAREST_MIPMAP_NEAREST = GL_NEAREST_MIPMAP_NEAREST,
COGL_MATERIAL_FILTER_LINEAR_MIPMAP_NEAREST = GL_LINEAR_MIPMAP_NEAREST,
COGL_MATERIAL_FILTER_NEAREST_MIPMAP_LINEAR = GL_NEAREST_MIPMAP_LINEAR,
COGL_MATERIAL_FILTER_LINEAR_MIPMAP_LINEAR = GL_LINEAR_MIPMAP_LINEAR
} CoglMaterialFilter;
/**
* CoglMaterialWrapMode:
* @COGL_MATERIAL_WRAP_MODE_REPEAT: The texture will be repeated. This
* is useful for example to draw a tiled background.
* @COGL_MATERIAL_WRAP_MODE_CLAMP_TO_EDGE: The coordinates outside the
* range 0→1 will sample copies of the edge pixels of the
* texture. This is useful to avoid artifacts if only one copy of
* the texture is being rendered.
* @COGL_MATERIAL_WRAP_MODE_AUTOMATIC: Cogl will try to automatically
* decide which of the above two to use. For cogl_rectangle(), it
* will use repeat mode if any of the texture coordinates are
* outside the range 0→1, otherwise it will use clamp to edge. For
* cogl_polygon() and cogl_vertex_buffer_draw() it will always use
* repeat mode. This is the default value.
*
* The wrap mode specifies what happens when texture coordinates
* outside the range 0→1 are used. Note that if the filter mode is
* anything but %COGL_MATERIAL_FILTER_NEAREST then texels outside the
* range 0→1 might be used even when the coordinate is exactly 0 or 1
* because OpenGL will try to sample neighbouring pixels. For example
* if you are trying to render the full texture then you may get
* artifacts around the edges when the pixels from the other side are
* merged in if the wrap mode is set to repeat.
*
* Since: 1.4
*/
/* GL_ALWAYS is just used here as a value that is known not to clash
with any valid GL wrap modes */
typedef enum {
COGL_MATERIAL_WRAP_MODE_REPEAT = GL_REPEAT,
COGL_MATERIAL_WRAP_MODE_CLAMP_TO_EDGE = GL_CLAMP_TO_EDGE,
COGL_MATERIAL_WRAP_MODE_AUTOMATIC = GL_ALWAYS
} CoglMaterialWrapMode;
/**
* cogl_material_new:
*
* Allocates and initializes a blank white material
*
* Return value: a handle to the new material
*/
CoglHandle
cogl_material_new (void);
/**
* cogl_material_copy:
* @source: the handle for the material to copy
*
* Creates a new material handle with the configuration copied from the
* source material.
*
* We would strongly advise developers to always aim to use
* cogl_material_copy() instead of cogl_material_new() whenever there will
* be any similarity between two materials. Copying a material helps Cogl
* keep track of a materials ancestry which we may use to help minimize GPU
* state changes.
*
* Returns: a handle to the new material
*
* Since: 1.2
*/
CoglHandle
cogl_material_copy (CoglHandle source);
#ifndef COGL_DISABLE_DEPRECATED
/**
* cogl_material_ref:
* @handle: a @CoglHandle.
*
* Increment the reference count for a cogl material.
*
* Return value: the @handle.
*
* Since: 1.0
*
* Deprecated: 1.2: Use cogl_handle_ref() instead
*/
CoglHandle
cogl_material_ref (CoglHandle handle) G_GNUC_DEPRECATED;
/**
* cogl_material_unref:
* @handle: a @CoglHandle.
*
* Decrement the reference count for a cogl material.
*
* Since: 1.0
*
* Deprecated: 1.2: Use cogl_handle_unref() instead
*/
void
cogl_material_unref (CoglHandle handle) G_GNUC_DEPRECATED;
#endif /* COGL_DISABLE_DEPRECATED */
/**
* cogl_is_material:
* @handle: A CoglHandle
*
* Gets whether the given handle references an existing material object.
*
* Return value: %TRUE if the handle references a #CoglMaterial,
* %FALSE otherwise
*/
gboolean
cogl_is_material (CoglHandle handle);
/**
* cogl_material_set_color:
* @material: A CoglMaterial object
* @color: The components of the color
*
* Sets the basic color of the material, used when no lighting is enabled.
*
* Note that if you don't add any layers to the material 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)
*
* Since: 1.0
*/
void
cogl_material_set_color (CoglHandle material,
const CoglColor *color);
/**
* cogl_material_set_color4ub:
* @material: A CoglMaterial object
* @red: The red component
* @green: The green component
* @blue: The blue component
* @alpha: The alpha component
*
* Sets the basic color of the material, used when no lighting is enabled.
*
* The default value is (0xff, 0xff, 0xff, 0xff)
*
* Since: 1.0
*/
void
cogl_material_set_color4ub (CoglHandle material,
guint8 red,
guint8 green,
guint8 blue,
guint8 alpha);
/**
* cogl_material_set_color4f:
* @material: A CoglMaterial object
* @red: The red component
* @green: The green component
* @blue: The blue component
* @alpha: The alpha component
*
* Sets the basic color of the material, used when no lighting is enabled.
*
* The default value is (1.0, 1.0, 1.0, 1.0)
*
* Since: 1.0
*/
void
cogl_material_set_color4f (CoglHandle material,
float red,
float green,
float blue,
float alpha);
/**
* cogl_material_get_color:
* @material: A CoglMaterial object
* @color: (out): The location to store the color
*
* Retrieves the current material color.
*
* Since: 1.0
*/
void
cogl_material_get_color (CoglHandle material,
CoglColor *color);
/**
* cogl_material_set_ambient:
* @material: A CoglMaterial object
* @ambient: The components of the desired ambient color
*
* Sets the material'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)
*
* Since: 1.0
*/
void
cogl_material_set_ambient (CoglHandle material,
const CoglColor *ambient);
/**
* cogl_material_get_ambient:
* @material: A CoglMaterial object
* @ambient: The location to store the ambient color
*
* Retrieves the current ambient color for @material
*
* Since: 1.0
*/
void
cogl_material_get_ambient (CoglHandle material,
CoglColor *ambient);
/**
* cogl_material_set_diffuse:
* @material: A CoglMaterial object
* @diffuse: The components of the desired diffuse color
*
* Sets the material'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)
*
* Since: 1.0
*/
void
cogl_material_set_diffuse (CoglHandle material,
const CoglColor *diffuse);
/**
* cogl_material_get_diffuse:
* @material: A CoglMaterial object
* @diffuse: The location to store the diffuse color
*
* Retrieves the current diffuse color for @material
*
* Since: 1.0
*/
void
cogl_material_get_diffuse (CoglHandle material,
CoglColor *diffuse);
/**
* cogl_material_set_ambient_and_diffuse:
* @material: A CoglMaterial object
* @color: The components of the desired ambient and diffuse colors
*
* Conveniently sets the diffuse and ambient color of @material at the same
* time. See cogl_material_set_ambient() and cogl_material_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)
*
* Since: 1.0
*/
void
cogl_material_set_ambient_and_diffuse (CoglHandle material,
const CoglColor *color);
/**
* cogl_material_set_specular:
* @material: A CoglMaterial object
* @specular: The components of the desired specular color
*
* Sets the material'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)
*
* Since: 1.0
*/
void
cogl_material_set_specular (CoglHandle material,
const CoglColor *specular);
/**
* cogl_material_get_specular:
* @material: A CoglMaterial object
* @specular: The location to store the specular color
*
* Retrieves the materials current specular color.
*
* Since: 1.0
*/
void
cogl_material_get_specular (CoglHandle material,
CoglColor *specular);
/**
* cogl_material_set_shininess:
* @material: A CoglMaterial object
* @shininess: The desired shininess; range: [0.0, 1.0]
*
* Sets the materials shininess, in the standard OpenGL lighting model,
* which determines how specular highlights are calculated. A higher
* @shininess will produce smaller brigher highlights.
*
* The default value is 0.0
*
* Since: 1.0
*/
void
cogl_material_set_shininess (CoglHandle material,
float shininess);
/**
* cogl_material_get_shininess:
* @material: A CoglMaterial object
*
* Retrieves the materials current emission color.
*
* Return value: The materials current shininess value
*
* Since: 1.0
*/
float
cogl_material_get_shininess (CoglHandle material);
/**
* cogl_material_set_emission:
* @material: A CoglMaterial object
* @emission: The components of the desired emissive color
*
* Sets the material'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)
*
* Since: 1.0
*/
void
cogl_material_set_emission (CoglHandle material,
const CoglColor *emission);
/**
* cogl_material_get_emission:
* @material: A CoglMaterial object
* @emission: The location to store the emission color
*
* Retrieves the materials current emission color.
*
* Since: 1.0
*/
void
cogl_material_get_emission (CoglHandle material,
CoglColor *emission);
/**
* CoglMaterialAlphaFunc:
* @COGL_MATERIAL_ALPHA_FUNC_NEVER: Never let the fragment through.
* @COGL_MATERIAL_ALPHA_FUNC_LESS: Let the fragment through if the incoming
* alpha value is less than the reference alpha value
* @COGL_MATERIAL_ALPHA_FUNC_EQUAL: Let the fragment through if the incoming
* alpha value equals the reference alpha value
* @COGL_MATERIAL_ALPHA_FUNC_LEQUAL: Let the fragment through if the incoming
* alpha value is less than or equal to the reference alpha value
* @COGL_MATERIAL_ALPHA_FUNC_GREATER: Let the fragment through if the incoming
* alpha value is greater than the reference alpha value
* @COGL_MATERIAL_ALPHA_FUNC_NOTEQUAL: Let the fragment through if the incoming
* alpha value does not equal the reference alpha value
* @COGL_MATERIAL_ALPHA_FUNC_GEQUAL: Let the fragment through if the incoming
* alpha value is greater than or equal to the reference alpha value.
* @COGL_MATERIAL_ALPHA_FUNC_ALWAYS: Always let the fragment through.
*
* Alpha testing happens before blending primitives with the framebuffer and
* gives an opportunity to discard fragments based on a comparison with the
* incoming alpha value and a reference alpha value. The #CoglMaterialAlphaFunc
* determines how the comparison is done.
*/
typedef enum {
COGL_MATERIAL_ALPHA_FUNC_NEVER = GL_NEVER,
COGL_MATERIAL_ALPHA_FUNC_LESS = GL_LESS,
COGL_MATERIAL_ALPHA_FUNC_EQUAL = GL_EQUAL,
COGL_MATERIAL_ALPHA_FUNC_LEQUAL = GL_LEQUAL,
COGL_MATERIAL_ALPHA_FUNC_GREATER = GL_GREATER,
COGL_MATERIAL_ALPHA_FUNC_NOTEQUAL = GL_NOTEQUAL,
COGL_MATERIAL_ALPHA_FUNC_GEQUAL = GL_GEQUAL,
COGL_MATERIAL_ALPHA_FUNC_ALWAYS = GL_ALWAYS
} CoglMaterialAlphaFunc;
/**
* cogl_material_set_alpha_test_function:
* @material: A CoglMaterial object
* @alpha_func: A @CoglMaterialAlphaFunc constant
* @alpha_reference: A reference point that the chosen alpha function uses
* to compare incoming fragments to.
*
* 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_MATERIAL_ALPHA_FUNC_ALWAYS
*
* Since: 1.0
*/
void
cogl_material_set_alpha_test_function (CoglHandle material,
CoglMaterialAlphaFunc alpha_func,
float alpha_reference);
/**
* cogl_material_set_blend:
* @material: A CoglMaterial object
* @blend_string: A <link linkend="cogl-Blend-Strings">Cogl blend string</link>
* 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.
*
* If not already familiar; please refer <link linkend="cogl-Blend-Strings">here</link>
* 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:
*
* |[
* &lt;channel-mask&gt;=ADD(SRC_COLOR*(&lt;factor&gt;), DST_COLOR*(&lt;factor&gt;))
* ]|
*
* <warning>The brackets around blend factors are currently not
* optional!</warning>
*
* This is the list of source-names usable as blend factors:
* <itemizedlist>
* <listitem><para>SRC_COLOR: The color of the in comming fragment</para></listitem>
* <listitem><para>DST_COLOR: The color of the framebuffer</para></listitem>
* <listitem><para>CONSTANT: The constant set via cogl_material_set_blend_constant()</para></listitem>
* </itemizedlist>
*
* The source names can be used according to the
* <link linkend="cogl-Blend-String-syntax">color-source and factor syntax</link>,
* so for example "(1-SRC_COLOR[A])" would be a valid factor, as would
* "(CONSTANT[RGB])"
*
* These can also be used as factors:
* <itemizedlist>
* <listitem>0: (0, 0, 0, 0)</listitem>
* <listitem>1: (1, 1, 1, 1)</listitem>
* <listitem>SRC_ALPHA_SATURATE_FACTOR: (f,f,f,1) where f = MIN(SRC_COLOR[A],1-DST_COLOR[A])</listitem>
* </itemizedlist>
*
* <note>Remember; all color components are normalized to the range [0, 1]
* before computing the result of blending.</note>
*
* <example id="cogl-Blend-Strings-blend-unpremul">
* <title>Blend Strings/1</title>
* <para>Blend a non-premultiplied source over a destination with
* premultiplied alpha:</para>
* <programlisting>
* "RGB = ADD(SRC_COLOR*(SRC_COLOR[A]), DST_COLOR*(1-SRC_COLOR[A]))"
* "A = ADD(SRC_COLOR, DST_COLOR*(1-SRC_COLOR[A]))"
* </programlisting>
* </example>
*
* <example id="cogl-Blend-Strings-blend-premul">
* <title>Blend Strings/2</title>
* <para>Blend a premultiplied source over a destination with
* premultiplied alpha</para>
* <programlisting>
* "RGBA = ADD(SRC_COLOR, DST_COLOR*(1-SRC_COLOR[A]))"
* </programlisting>
* </example>
*
* The default blend string is:
* |[
* RGBA = ADD (SRC_COLOR, DST_COLOR*(1-SRC_COLOR[A]))
* ]|
*
* That gives normal alpha-blending when the calculated color for the material
* is in premultiplied form.
*
* Return value: %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: 1.0
*/
gboolean
cogl_material_set_blend (CoglHandle material,
const char *blend_string,
GError **error);
/**
* cogl_material_set_blend_constant:
* @material: A CoglMaterial object
* @constant_color: The constant color you want
*
* When blending is setup to reference a CONSTANT blend factor then
* blending will depend on the constant set with this function.
*
* Since: 1.0
*/
void
cogl_material_set_blend_constant (CoglHandle material,
CoglColor *constant_color);
/**
* cogl_material_set_layer:
* @material: A #CoglHandle for a material object
* @layer_index: the index of the layer
* @texture: a #CoglHandle for the layer object
*
* In addition to the standard OpenGL lighting model a Cogl material may have
* one or more layers comprised of textures that can be blended together in
* order, with a number of different texture combine modes. This function
* defines a new texture layer.
*
* The index values of multiple layers do not have to be consecutive; it is
* only their relative order that is important.
*
* <note>In the future, we may define other types of material layers, such
* as purely GLSL based layers.</note>
*
* Since: 1.0
*/
void
cogl_material_set_layer (CoglHandle material,
int layer_index,
CoglHandle texture);
/**
* cogl_material_remove_layer:
* @material: A CoglMaterial object
* @layer_index: Specifies the layer you want to remove
*
* This function removes a layer from your material
*/
void
cogl_material_remove_layer (CoglHandle material,
int layer_index);
/**
* cogl_material_set_layer_combine:
* @material: A CoglMaterial object
* @layer_index: Specifies the layer you want define a combine function for
* @blend_string: A <link linkend="cogl-Blend-Strings">Cogl blend string</link>
* 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.
*
* If not already familiar; you can refer
* <link linkend="cogl-Blend-Strings">here</link> for an overview of what blend
* strings are and there syntax.
*
* These are all the functions available for texture combining:
* <itemizedlist>
* <listitem>REPLACE(arg0) = arg0</listitem>
* <listitem>MODULATE(arg0, arg1) = arg0 x arg1</listitem>
* <listitem>ADD(arg0, arg1) = arg0 + arg1</listitem>
* <listitem>ADD_SIGNED(arg0, arg1) = arg0 + arg1 - 0.5</listitem>
* <listitem>INTERPOLATE(arg0, arg1, arg2) = arg0 x arg2 + arg1 x (1 - arg2)</listitem>
* <listitem>SUBTRACT(arg0, arg1) = arg0 - arg1</listitem>
* <listitem>
* <programlisting>
* 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))
* </programlisting>
* </listitem>
* <listitem>
* <programlisting>
* 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))
* </programlisting>
* </listitem>
* </itemizedlist>
*
* Refer to the
* <link linkend="cogl-Blend-String-syntax">color-source syntax</link> for
* describing the arguments. The valid source names for texture combining
* are:
* <variablelist>
* <varlistentry>
* <term>TEXTURE</term>
* <listitem>Use the color from the current texture layer</listitem>
* </varlistentry>
* <varlistentry>
* <term>TEXTURE_0, TEXTURE_1, etc</term>
* <listitem>Use the color from the specified texture layer</listitem>
* </varlistentry>
* <varlistentry>
* <term>CONSTANT</term>
* <listitem>Use the color from the constant given with
* cogl_material_set_layer_constant()</listitem>
* </varlistentry>
* <varlistentry>
* <term>PRIMARY</term>
* <listitem>Use the color of the material as set with
* cogl_material_set_color()</listitem>
* </varlistentry>
* <varlistentry>
* <term>PREVIOUS</term>
* <listitem>Either use the texture color from the previous layer, or
* if this is layer 0, use the color of the material as set with
* cogl_material_set_color()</listitem>
* </varlistentry>
* </variablelist>
*
* <refsect2 id="cogl-Layer-Combine-Examples">
* <title>Layer Combine Examples</title>
* <para>This is effectively what the default blending is:</para>
* <informalexample><programlisting>
* RGBA = MODULATE (PREVIOUS, TEXTURE)
* </programlisting></informalexample>
* <para>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_material_set_layer_constant.</para>
* <informalexample><programlisting>
* RGBA = INTERPOLATE (PREVIOUS, TEXTURE, CONSTANT[A])
* </programlisting></informalexample>
* </refsect2>
*
* <note>You can't give a multiplication factor for arguments as you can
* with blending.</note>
*
* Return value: %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: 1.0
*/
gboolean
cogl_material_set_layer_combine (CoglHandle material,
int layer_index,
const char *blend_string,
GError **error);
/**
* cogl_material_set_layer_combine_constant:
* @material: A CoglMaterial object
* @layer_index: Specifies the layer you want to specify a constant used
* for texture combining
* @constant: The constant color you want
*
* When you are using the 'CONSTANT' color source in a layer combine
* description then you can use this function to define its value.
*
* Since: 1.0
*/
void
cogl_material_set_layer_combine_constant (CoglHandle material,
int layer_index,
CoglColor *constant);
/**
* cogl_material_set_layer_matrix:
* @material: A CoglMaterial object
* @layer_index: the index for the layer inside @material
* @matrix: the transformation matrix for the layer
*
* This function lets you set a matrix that can be used to e.g. translate
* and rotate a single layer of a material used to fill your geometry.
*/
void
cogl_material_set_layer_matrix (CoglHandle material,
int layer_index,
CoglMatrix *matrix);
/**
* cogl_material_get_layers:
* @material: a #CoglHandle for a material
*
* This function lets you access a materials internal list of layers
* for iteration.
*
* Return value: (element-type Handle) (transfer none): A list of
* #CoglHandle<!-- -->'s that can be passed to the cogl_material_layer_*
* functions. The list is owned by COGL and it should not be modified or
* freed
*/
G_CONST_RETURN GList *
cogl_material_get_layers (CoglHandle material);
/**
* cogl_material_get_n_layers:
* @material: a #CoglHandle for a material
*
* Retrieves the number of layers defined for the given @material
*
* Return value: the number of layers
*
* Since: 1.0
*/
int
cogl_material_get_n_layers (CoglHandle material);
/**
* CoglMaterialLayerType:
* @COGL_MATERIAL_LAYER_TYPE_TEXTURE: The layer represents a
* <link linkend="cogl-Textures">texture</link>
*
* Available types of layers for a #CoglMaterial. This enumeration
* might be expanded in later versions.
*
* Since: 1.0
*/
typedef enum {
COGL_MATERIAL_LAYER_TYPE_TEXTURE
} CoglMaterialLayerType;
/**
* cogl_material_layer_get_type:
* @layer: A #CoglHandle for a material layer
*
* Retrieves the type of the layer
*
* Currently there is only one type of layer defined:
* %COGL_MATERIAL_LAYER_TYPE_TEXTURE, but considering we may add purely GLSL
* based layers in the future, you should write code that checks the type
* first.
*
* Return value: the type of the layer
*/
CoglMaterialLayerType
cogl_material_layer_get_type (CoglHandle layer);
/**
* cogl_material_layer_get_texture:
* @layer: A #CoglHandle for a material layer
*
* Extracts a texture handle for a specific layer.
*
* <note>In the future Cogl may support purely GLSL based layers; for those
* layers this function which will likely return %COGL_INVALID_HANDLE if you
* try to get the texture handle from them. Considering this scenario, you
* should call cogl_material_layer_get_type() first in order check it is of
* type %COGL_MATERIAL_LAYER_TYPE_TEXTURE before calling this function.</note>
*
* Return value: a #CoglHandle for the texture inside the layer
*/
CoglHandle
cogl_material_layer_get_texture (CoglHandle layer);
/**
* cogl_material_layer_get_min_filter:
* @layer: a #CoglHandle for a material layer
*
* Queries the currently set downscaling filter for a material layer
*
* Return value: the current downscaling filter
*/
CoglMaterialFilter
cogl_material_layer_get_min_filter (CoglHandle layer);
/**
* cogl_material_layer_get_mag_filter:
* @layer: a #CoglHandle for a material layer
*
* Queries the currently set downscaling filter for a material later
*
* Return value: the current downscaling filter
*/
CoglMaterialFilter
cogl_material_layer_get_mag_filter (CoglHandle layer);
/**
* cogl_material_set_layer_filters:
* @material: a #CoglHandle to a material.
* @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.
*
* Changes the decimation and interpolation filters used when a texture is
* drawn at other scales than 100%.
*/
void
cogl_material_set_layer_filters (CoglHandle material,
int layer_index,
CoglMaterialFilter min_filter,
CoglMaterialFilter mag_filter);
/**
* cogl_material_set_layer_wrap_mode_s:
* @material: a #CoglHandle to a material.
* @layer_index: the layer number to change.
* @mode: the new wrap mode
*
* Sets the wrap mode for the 's' coordinate of texture lookups on this layer.
*
* Since: 1.4
*/
void
cogl_material_set_layer_wrap_mode_s (CoglHandle material,
int layer_index,
CoglMaterialWrapMode mode);
/**
* cogl_material_set_layer_wrap_mode_t:
* @material: a #CoglHandle to a material.
* @layer_index: the layer number to change.
* @mode: the new wrap mode
*
* Sets the wrap mode for the 't' coordinate of texture lookups on this layer.
*
* Since: 1.4
*/
void
cogl_material_set_layer_wrap_mode_t (CoglHandle material,
int layer_index,
CoglMaterialWrapMode mode);
/**
* cogl_material_set_layer_wrap_mode:
* @material: a #CoglHandle to a material.
* @layer_index: the layer number to change.
* @mode: the new wrap mode
*
* Sets the wrap mode for both coordinates of texture lookups on this
* layer. This is equivalent to calling
* cogl_material_set_layer_wrap_mode_s() and
* cogl_material_set_layer_wrap_mode_t() separately.
*
* Since: 1.4
*/
void
cogl_material_set_layer_wrap_mode (CoglHandle material,
int layer_index,
CoglMaterialWrapMode mode);
/**
* cogl_material_layer_get_wrap_mode_s:
* @layer: a #CoglHandle to a material mayer.
*
* Gets the wrap mode for the 's' coordinate of texture lookups on this layer.
*
* Since: 1.4
*/
CoglMaterialWrapMode
cogl_material_layer_get_wrap_mode_s (CoglHandle layer);
/**
* cogl_material_layer_get_wrap_mode_t:
* @layer: a #CoglHandle to a material mayer.
*
* Gets the wrap mode for the 't' coordinate of texture lookups on this layer.
*
* Since: 1.4
*/
CoglMaterialWrapMode
cogl_material_layer_get_wrap_mode_t (CoglHandle layer);
G_END_DECLS
#endif /* __COGL_MATERIAL_H__ */
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