182 lines
7.8 KiB
C
182 lines
7.8 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2011 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see
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* <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
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#error "Only <cogl/cogl.h> can be included directly."
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#endif
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#ifndef __COGL_META_TEXTURE_H__
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#define __COGL_META_TEXTURE_H__
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#include <cogl/cogl-pipeline-layer-state.h>
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#include <glib.h>
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G_BEGIN_DECLS
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/**
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* SECTION:cogl-meta-texture
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* @short_description: Interface for high-level textures built from
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* low-level textures like #CoglTexture2D and
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* #CoglTexture3D.
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*
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* Cogl helps to make it easy to deal with high level textures such
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* as #CoglAtlasTexture<!-- -->s, #CoglSubTexture<!-- -->s,
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* #CoglTexturePixmapX11 textures and #CoglTexture2DSliced textures
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* consistently.
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*
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* A #CoglMetaTexture is a texture that might internally be
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* represented by one or more low-level #CoglTexture<!-- -->s
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* such as #CoglTexture2D or #CoglTexture3D. These low-level textures
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* are the only ones that a GPU really understands but because
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* applications often want more high-level texture abstractions
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* (such as storing multiple textures inside one larger "atlas"
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* texture) it's desirable to be able to deal with these
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* using a common interface.
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*
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* For example the GPU is not able to automatically handle repeating a
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* texture that is part of a larger atlas texture but if you use
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* %COGL_PIPELINE_WRAP_MODE_REPEAT with an atlas texture when drawing
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* with cogl_rectangle() you should see that it "Just Works™" - at
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* least if you don't use multi-texturing. The reason this works is
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* because cogl_rectangle() internally understands the #CoglMetaTexture
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* interface and is able to manually resolve the low-level textures
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* using this interface and by making multiple draw calls it can
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* emulate the texture repeat modes.
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*
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* Cogl doesn't aim to pretend that meta-textures are just like real
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* textures because it would get extremely complex to try and emulate
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* low-level GPU semantics transparently for these textures. The low
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* level drawing APIs of Cogl, such as cogl_draw_attributes() don't
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* actually know anything about the #CoglMetaTexture interface and its
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* the developer's responsibility to resolve all textures referenced by
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* a #CoglPipeline to low-level textures before drawing.
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*
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* If you want to develop custom primitive APIs like cogl_rectangle()
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* and you want to support drawing with #CoglAtlasTexture<!-- -->s
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* or #CoglSubTexture<!-- -->s for example, then you will need to use
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* this #CoglMetaTexture interface to be able to resolve high-level
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* textures into low-level textures before drawing with Cogl's
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* low-level drawing APIs such as cogl_draw_attributes().
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*
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* <note>Most developers won't need to use this interface directly
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* but still it is worth understanding the distinction between
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* low-level and meta textures because you may find other references
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* in the documentation that detail limitations of using
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* meta-textures.</note>
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*/
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typedef struct _CoglMetaTexture CoglMetaTexture;
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#define COGL_META_TEXTURE(X) ((CoglMetaTexture *)X)
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/**
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* CoglMetaTextureCallback:
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* @sub_texture: A low-level #CoglTexture making up part of a
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* #CoglMetaTexture.
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* @sub_texture_coords: A float 4-tuple ordered like
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* (tx1,ty1,tx2,ty2) defining what region of the
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* current @sub_texture maps to a sub-region of a
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* #CoglMetaTexture. (tx1,ty1) is the top-left
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* sub-region coordinate and (tx2,ty2) is the
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* bottom-right. These are low-level texture
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* coordinates.
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* @meta_coords: A float 4-tuple ordered like (tx1,ty1,tx2,ty2)
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* defining what sub-region of a #CoglMetaTexture this
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* low-level @sub_texture maps too. (tx1,ty1) is
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* the top-left sub-region coordinate and (tx2,ty2) is
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* the bottom-right. These are high-level meta-texture
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* coordinates.
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* @user_data: A private pointer passed to
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* cogl_meta_texture_foreach_in_region().
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*
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* A callback used with cogl_meta_texture_foreach_in_region() to
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* retrieve details of all the low-level #CoglTexture<!-- -->s that
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* make up a given #CoglMetaTexture.
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*
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* Since: 1.10
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* Stability: unstable
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*/
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typedef void (*CoglMetaTextureCallback) (CoglTexture *sub_texture,
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const float *sub_texture_coords,
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const float *meta_coords,
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void *user_data);
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/**
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* cogl_meta_texture_foreach_in_region:
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* @meta_texture: An object implementing the #CoglMetaTexture
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* interface.
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* @tx_1: The top-left x coordinate of the region to iterate
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* @ty_1: The top-left y coordinate of the region to iterate
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* @tx_2: The bottom-right x coordinate of the region to iterate
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* @ty_2: The bottom-right y coordinate of the region to iterate
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* @wrap_s: The wrap mode for the x-axis
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* @wrap_t: The wrap mode for the y-axis
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* @callback: A #CoglMetaTextureCallback pointer to be called
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* for each low-level texture within the specified region.
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* @user_data: A private pointer that is passed to @callback.
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*
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* Allows you to manually iterate the low-level textures that define a
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* given region of a high-level #CoglMetaTexture.
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*
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* For example cogl_texture_2d_sliced_new_with_size() can be used to
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* create a meta texture that may slice a large image into multiple,
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* smaller power-of-two sized textures. These high level textures are
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* not directly understood by a GPU and so this API must be used to
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* manually resolve the underlying textures for drawing.
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*
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* All high level textures (#CoglAtlasTexture, #CoglSubTexture,
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* #CoglTexturePixmapX11, and #CoglTexture2DSliced) can be handled
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* consistently using this interface which greately simplifies
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* implementing primitives that support all texture types.
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*
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* For example if you use the cogl_rectangle() API then Cogl will
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* internally use this API to resolve the low level textures of any
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* meta textures you have associated with CoglPipeline layers.
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*
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* <note>The low level drawing APIs such as cogl_draw_attributes()
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* don't understand the #CoglMetaTexture interface and so it is your
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* responsibility to use this API to resolve all CoglPipeline
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* textures into low-level textures before drawing.</note>
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*
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* For each low-level texture that makes up part of the given region
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* of the @meta_texture, @callback is called specifying how the
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* low-level texture maps to the original region.
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*
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* Since: 1.10
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* Stability: unstable
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*/
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void
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cogl_meta_texture_foreach_in_region (CoglMetaTexture *meta_texture,
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float tx_1,
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float ty_1,
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float tx_2,
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float ty_2,
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CoglPipelineWrapMode wrap_s,
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CoglPipelineWrapMode wrap_t,
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CoglMetaTextureCallback callback,
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void *user_data);
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G_END_DECLS
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#endif /* __COGL_META_TEXTURE_H__ */
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