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Although we use GLib internally in Cogl we would rather not leak GLib api through Cogl's own api, except through explicitly namespaced cogl_glib_ / cogl_gtype_ feature apis. One of the benefits we see to not leaking GLib through Cogl's public API is that documentation for Cogl won't need to first introduce the Glib API to newcomers, thus hopefully lowering the barrier to learning Cogl. This patch provides a Cogl specific typedef for reporting runtime errors which by no coincidence matches the typedef for GError exactly. If Cogl is built with --enable-glib (default) then developers can even safely assume that a CoglError is a GError under the hood. This patch also enforces a consistent policy for when NULL is passed as an error argument and an error is thrown. In this case we log the error and abort the application, instead of silently ignoring it. In common cases where nothing has been implemented to handle a particular error and/or where applications are just printing the error and aborting themselves then this saves some typing. This also seems more consistent with language based exceptions which usually cause a program to abort if they are not explicitly caught (which passing a non-NULL error signifies in this case) Since this policy for NULL error pointers is stricter than the standard GError convention, there is a clear note in the documentation to warn developers that are used to using the GError api. Reviewed-by: Neil Roberts <neil@linux.intel.com> (cherry picked from commit b068d5ea09ab32c37e8c965fc8582c85d1b2db46) Note: Since we can't change the Cogl 1.x api the patch was changed to not rename _error_quark() functions to be _error_domain() functions and although it's a bit ugly, instead of providing our own CoglError type that's compatible with GError we simply #define CoglError to GError unless Cogl is built with glib disabled. Note: this patch does technically introduce an API break since it drops the cogl_error_get_type() symbol generated by glib-mkenum (Since the CoglError enum was replaced by a CoglSystemError enum) but for now we are assuming that this will not affect anyone currently using the Cogl API. If this does turn out to be a problem in practice then we would be able to fix this my manually copying an implementation of cogl_error_get_type() generated by glib-mkenum into a compatibility source file and we could also define the original COGL_ERROR_ enums for compatibility too. Note: another minor concern with cherry-picking this patch to the 1.14 branch is that an api scanner would be lead to believe that some APIs have changed, and for example the gobject-introspection parser which understands the semantics of GError will not understand the semantics of CoglError. We expect most people that have tried to use gobject-introspection with Cogl already understand though that it is not well suited to generating bindings of the Cogl api anyway and we aren't aware or anyone depending on such bindings for apis involving GErrors. (GnomeShell only makes very-very minimal use of Cogl via the gjs bindings for the cogl_rectangle and cogl_color apis.) The main reason we have cherry-picked this patch to the 1.14 branch even given the above concerns is that without it it would become very awkward for us to cherry-pick other beneficial patches from master.
205 lines
7.8 KiB
C
205 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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* Authors:
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* Robert Bragg <robert@linux.intel.com>
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*/
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#ifndef __COGL_TEXURE_RECTANGLE_H
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#define __COGL_TEXURE_RECTANGLE_H
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#include "cogl-context.h"
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G_BEGIN_DECLS
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/**
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* SECTION:cogl-texture-rectangle
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* @short_description: Functions for creating and manipulating rectangle
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* textures for use with non-normalized coordinates.
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*
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* These functions allow low-level "rectangle" textures to be allocated.
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* These textures are never constrained to power-of-two sizes but they
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* also don't support having a mipmap and can only be wrapped with
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* %COGL_PIPELINE_WRAP_MODE_CLAMP_TO_EDGE.
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*
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* The most notable difference between rectangle textures and 2D
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* textures is that rectangle textures are sampled using un-normalized
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* texture coordinates, so instead of using coordinates (0,0) and
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* (1,1) to map to the top-left and bottom right corners of the
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* texture you would instead use (0,0) and (width,height).
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*
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* The use of non-normalized coordinates can be particularly
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* convenient when writing glsl shaders that use a texture as a lookup
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* table since you don't need to upload separate uniforms to map
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* normalized coordinates to texels.
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*
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* If you want to sample from a rectangle texture from GLSL you should
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* use the sampler2DRect sampler type.
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*
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* Applications wanting to use #CoglTextureRectangle should first check
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* for the %COGL_FEATURE_ID_TEXTURE_RECTANGLE feature using
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* cogl_has_feature().
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*/
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typedef struct _CoglTextureRectangle CoglTextureRectangle;
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#define COGL_TEXTURE_RECTANGLE(X) ((CoglTextureRectangle *)X)
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/**
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* cogl_is_texture_rectangle:
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* @object: A #CoglObject
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*
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* Gets whether the given object references an existing
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* #CoglTextureRectangle object.
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*
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* Return value: %TRUE if the object references a
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* #CoglTextureRectangle, %FALSE otherwise.
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*/
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CoglBool
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cogl_is_texture_rectangle (void *object);
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/**
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* cogl_texture_rectangle_new_with_size:
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* @context: A #CoglContext pointer
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* @width: The texture width to allocate
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* @height: The texture height to allocate
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* @internal_format: The desired internal texture format
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* @error: An optional CoglError pointer for reporting exceptions
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*
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* Allocates a new #CoglTextureRectangle texture with a given @width, @height
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* and @internal_format. This texture is a low-level texture that
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* the GPU can sample from directly unlike high-level textures such
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* as #CoglTexture2DSliced and #CoglAtlasTexture.
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*
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* <note>Unlike for #CoglTexture2D textures, coordinates for
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* #CoglTextureRectangle textures should not be normalized. So instead
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* of using the coordinate (1, 1) to sample the bottom right corner of
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* a rectangle texture you would use (@width, @height) where @width
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* and @height are the width and height of the texture.</note>
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*
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* <note>If you want to sample from a rectangle texture from GLSL you
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* should use the sampler2DRect sampler type.</note>
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*
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* <note>Applications wanting to use #CoglTextureRectangle should
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* first check for the %COGL_FEATURE_ID_TEXTURE_RECTANGLE feature
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* using cogl_has_feature().</note>
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*
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* Returns: A pointer to a newly allocated #CoglRectangle texture
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* or if the size was too large or there wasn't enough memory
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* %NULL is returned and @error set.
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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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CoglTextureRectangle *
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cogl_texture_rectangle_new_with_size (CoglContext *ctx,
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int width,
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int height,
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CoglPixelFormat internal_format,
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CoglError **error);
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/**
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* cogl_texture_rectangle_new_from_bitmap:
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* @bitmap: A #CoglBitmap
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* @internal_format: the #CoglPixelFormat to use for the GPU storage of the
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* texture
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* @error: A return location for a CoglError or %NULL
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*
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* Allocates a new #CoglTextureRectangle texture which will be
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* initialized with the pixel data from @bitmap. Internally the data
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* will be stored in the format given by @internal_format. This
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* texture is a low-level texture that the GPU can sample from
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* directly unlike high-level textures such as #CoglTexture2DSliced
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* and #CoglAtlasTexture.
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*
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* <note>Unlike for #CoglTexture2D textures, coordinates for
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* #CoglTextureRectangle textures should not be normalized. So instead
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* of using the coordinate (1, 1) to sample the bottom right corner of
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* a rectangle texture you would use (@width, @height) where @width
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* and @height are the width and height of the texture.</note>
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*
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* <note>If you want to sample from a rectangle texture from GLSL you
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* should use the sampler2DRect sampler type.</note>
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*
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* <note>Applications wanting to use #CoglTextureRectangle should
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* first check for the %COGL_FEATURE_ID_TEXTURE_RECTANGLE feature
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* using cogl_has_feature().</note>
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*
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* Returns: A pointer to a newly allocated #CoglRectangle texture
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* or if the size was too large or there wasn't enough memory
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* %NULL is returned and @error set.
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* Since: 2.0
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* Stability: unstable
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*/
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CoglTextureRectangle *
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cogl_texture_rectangle_new_from_bitmap (CoglBitmap *bitmap,
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CoglPixelFormat internal_format,
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CoglError **error);
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/**
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* cogl_texture_rectangle_new_from_foreign:
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* @ctx: A #CoglContext
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* @gl_handle: A GL handle for a GL_TEXTURE_RECTANGLE texture object
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* @width: Width of the foreign GL texture
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* @height: Height of the foreign GL texture
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* @internal_format: The format of the texture
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* @error: A #CoglError for exceptions
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*
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* Wraps an existing GL_TEXTURE_RECTANGLE texture object as a
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* #CoglTextureRectangle. This can be used for integrating Cogl with
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* software using OpenGL directly.
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*
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* <note>Unlike for #CoglTexture2D textures, coordinates for
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* #CoglTextureRectangle textures should not be normalized. So instead
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* of using the coordinate (1, 1) to sample the bottom right corner of
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* a rectangle texture you would use (@width, @height) where @width
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* and @height are the width and height of the texture.</note>
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*
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* <note>The results are undefined for passing an invalid @gl_handle
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* or if @width or @height don't have the correct texture
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* geometry.</note>
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*
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* <note>If you want to sample from a rectangle texture from GLSL you
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* should use the sampler2DRect sampler type.</note>
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*
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* <note>Applications wanting to use #CoglTextureRectangle should
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* first check for the %COGL_FEATURE_ID_TEXTURE_RECTANGLE feature
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* using cogl_has_feature().</note>
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* Returns: A newly allocated #CoglTextureRectangle, or if Cogl could
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* not validate the @gl_handle in some way (perhaps because
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* of an unsupported format) it will return %NULL and set
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* @error.
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*
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*/
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CoglTextureRectangle *
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cogl_texture_rectangle_new_from_foreign (CoglContext *ctx,
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unsigned int gl_handle,
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int width,
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int height,
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CoglPixelFormat format,
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CoglError **error);
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G_END_DECLS
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#endif /* __COGL_TEXURE_RECTANGLE_H */
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