6436cd073d
This declares the interface types CoglFramebuffer, CoglBuffer, CoglTexture, CoglMetaTexture and CoglPrimitiveTexture as void when including the public cogl.h header so that users don't have to use lots of C type casts between instance types and interface types. This also removes all of the COGL_XYZ() type cast macros since they do nothing more than compile time type casting but it's less readable if you haven't seen that coding pattern before. Unlike with gobject based apis that use per-type macros for casting and performing runtime type checking we instead prefer to do our runtime type checking internally within the front-end public apis when objects are passed into Cogl. This greatly reduces the verbosity for users of the api and may help reduce the chance of excessive runtime type checking that can sometimes be a problem. (cherry picked from commit 248a76f5eac7e5ae4fb45208577f9a55360812a7) Since we can't break the 1.x api this version of the patch actually defines compatible NOP macros within deprecated/cogl-type-casts.h
188 lines
8 KiB
C
188 lines
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(COGL_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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COGL_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_primitive_draw() 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
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* by 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
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* cogl_framebuffer_draw_rectangle() and you want to support drawing
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* with #CoglAtlasTexture<!-- -->s or #CoglSubTexture<!-- -->s for
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* example, then you will need to use this #CoglMetaTexture interface
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* to be able to resolve high-level textures into low-level textures
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* before drawing with Cogl's low-level drawing APIs such as
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* cogl_primitive_draw().
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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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#ifdef __COGL_H_INSIDE__
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/* For the public C api we typedef interface types as void to avoid needing
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* lots of casting in code and instead we will rely on runtime type checking
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* for these objects. */
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typedef void CoglMetaTexture;
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#else
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typedef struct _CoglMetaTexture CoglMetaTexture;
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#define COGL_META_TEXTURE(X) ((CoglMetaTexture *)X)
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#endif
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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_primitive_draw()
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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 textures
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* 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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COGL_END_DECLS
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#endif /* __COGL_META_TEXTURE_H__ */
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