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/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2011 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(COGL_COMPILATION)
#error "Only <cogl/cogl.h> can be included directly."
#endif
#ifndef __COGL_META_TEXTURE_H__
#define __COGL_META_TEXTURE_H__
#include <cogl/cogl-pipeline-layer-state.h>
#include <glib.h>
G_BEGIN_DECLS
/**
* SECTION:cogl-meta-texture
* @short_description: Interface for high-level textures built from
* low-level textures like #CoglTexture2D and
* #CoglTexture3D.
*
* Cogl helps to make it easy to deal with high level textures such
* as #CoglAtlasTexture<!-- -->s, #CoglSubTexture<!-- -->s,
* #CoglTexturePixmapX11 textures and #CoglTexture2DSliced textures
* consistently.
*
* A #CoglMetaTexture is a texture that might internally be
* represented by one or more low-level #CoglTexture<!-- -->s
* such as #CoglTexture2D or #CoglTexture3D. These low-level textures
* are the only ones that a GPU really understands but because
* applications often want more high-level texture abstractions
* (such as storing multiple textures inside one larger "atlas"
* texture) it's desirable to be able to deal with these
* using a common interface.
*
* For example the GPU is not able to automatically handle repeating a
* texture that is part of a larger atlas texture but if you use
* %COGL_PIPELINE_WRAP_MODE_REPEAT with an atlas texture when drawing
* with cogl_rectangle() you should see that it "Just Works™" - at
* least if you don't use multi-texturing. The reason this works is
* because cogl_rectangle() internally understands the #CoglMetaTexture
* interface and is able to manually resolve the low-level textures
* using this interface and by making multiple draw calls it can
* emulate the texture repeat modes.
*
* Cogl doesn't aim to pretend that meta-textures are just like real
* textures because it would get extremely complex to try and emulate
* low-level GPU semantics transparently for these textures. The low
* level drawing APIs of Cogl, such as cogl_draw_attributes() don't
* actually know anything about the #CoglMetaTexture interface and its
* the developer's responsibility to resolve all textures referenced by
* a #CoglPipeline to low-level textures before drawing.
*
* If you want to develop custom primitive APIs like cogl_rectangle()
* and you want to support drawing with #CoglAtlasTexture<!-- -->s
* or #CoglSubTexture<!-- -->s for example, then you will need to use
* this #CoglMetaTexture interface to be able to resolve high-level
* textures into low-level textures before drawing with Cogl's
* low-level drawing APIs such as cogl_draw_attributes().
*
* <note>Most developers won't need to use this interface directly
* but still it is worth understanding the distinction between
* low-level and meta textures because you may find other references
* in the documentation that detail limitations of using
* meta-textures.</note>
*/
typedef struct _CoglMetaTexture CoglMetaTexture;
#define COGL_META_TEXTURE(X) ((CoglMetaTexture *)X)
/**
* CoglMetaTextureCallback:
* @sub_texture: A low-level #CoglTexture making up part of a
* #CoglMetaTexture.
* @sub_texture_coords: A float 4-tuple ordered like
* (tx1,ty1,tx2,ty2) defining what region of the
* current @sub_texture maps to a sub-region of a
* #CoglMetaTexture. (tx1,ty1) is the top-left
* sub-region coordinate and (tx2,ty2) is the
* bottom-right. These are low-level texture
* coordinates.
* @meta_coords: A float 4-tuple ordered like (tx1,ty1,tx2,ty2)
* defining what sub-region of a #CoglMetaTexture this
* low-level @sub_texture maps too. (tx1,ty1) is
* the top-left sub-region coordinate and (tx2,ty2) is
* the bottom-right. These are high-level meta-texture
* coordinates.
* @user_data: A private pointer passed to
* cogl_meta_texture_foreach_in_region().
*
* A callback used with cogl_meta_texture_foreach_in_region() to
* retrieve details of all the low-level #CoglTexture<!-- -->s that
* make up a given #CoglMetaTexture.
*
* Since: 1.10
* Stability: unstable
*/
typedef void (*CoglMetaTextureCallback) (CoglTexture *sub_texture,
const float *sub_texture_coords,
const float *meta_coords,
void *user_data);
/**
* cogl_meta_texture_foreach_in_region:
* @meta_texture: An object implementing the #CoglMetaTexture
* interface.
* @tx_1: The top-left x coordinate of the region to iterate
* @ty_1: The top-left y coordinate of the region to iterate
* @tx_2: The bottom-right x coordinate of the region to iterate
* @ty_2: The bottom-right y coordinate of the region to iterate
* @wrap_s: The wrap mode for the x-axis
* @wrap_t: The wrap mode for the y-axis
* @callback: A #CoglMetaTextureCallback pointer to be called
* for each low-level texture within the specified region.
* @user_data: A private pointer that is passed to @callback.
*
* Allows you to manually iterate the low-level textures that define a
* given region of a high-level #CoglMetaTexture.
*
* For example cogl_texture_2d_sliced_new_with_size() can be used to
* create a meta texture that may slice a large image into multiple,
* smaller power-of-two sized textures. These high level textures are
* not directly understood by a GPU and so this API must be used to
* manually resolve the underlying textures for drawing.
*
* All high level textures (#CoglAtlasTexture, #CoglSubTexture,
* #CoglTexturePixmapX11, and #CoglTexture2DSliced) can be handled
* consistently using this interface which greately simplifies
* implementing primitives that support all texture types.
*
* For example if you use the cogl_rectangle() API then Cogl will
* internally use this API to resolve the low level textures of any
* meta textures you have associated with CoglPipeline layers.
*
* <note>The low level drawing APIs such as cogl_draw_attributes()
* don't understand the #CoglMetaTexture interface and so it is your
* responsibility to use this API to resolve all CoglPipeline
* textures into low-level textures before drawing.</note>
*
* For each low-level texture that makes up part of the given region
* of the @meta_texture, @callback is called specifying how the
* low-level texture maps to the original region.
*
* Since: 1.10
* Stability: unstable
*/
void
cogl_meta_texture_foreach_in_region (CoglMetaTexture *meta_texture,
float tx_1,
float ty_1,
float tx_2,
float ty_2,
CoglPipelineWrapMode wrap_s,
CoglPipelineWrapMode wrap_t,
CoglMetaTextureCallback callback,
void *user_data);
G_END_DECLS
#endif /* __COGL_META_TEXTURE_H__ */
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