mutter/cogl/cogl-texture-rectangle.h
Robert Bragg 90f106117f texture: Make CoglTextureRectangle experimentally public
This exposes CoglTextureRectangle in the experimental cogl 2.0 api. For
now we just expose a single constructor;
cogl_texture_rectangle_new_with_size() but we can add more later.

This is part of going work to improve our texture apis with more
emphasis on providing low-level access to the varying semantics of
different texture types understood by the gpu instead of only trying to
present a lowest common denominator api.

CoglTextureRectangle is notably useful for never being restricted to
power of two sizes and for being sampled with non-normalized texture
coordinates which can be convenient for use a lookup tables in glsl due
to not needing separate uniforms for mapping normalized coordinates to
texels. Unlike CoglTexture2D though rectangle textures can't have a
mipmap and they only support the _CLAMP_TO_EDGE wrap mode.

Applications wanting to use CoglTextureRectangle should first check
cogl_has_feature (COGL_FEATURE_ID_TEXTURE_RECTANGLE).

Reviewed-by: Neil Roberts <neil@linux.intel.com>
2011-11-01 12:03:02 +00:00

119 lines
4.2 KiB
C

/*
* 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/>.
*
*
* Authors:
* Robert Bragg <robert@linux.intel.com>
*/
#ifndef __COGL_TEXURE_RECTANGLE_H
#define __COGL_TEXURE_RECTANGLE_H
#include "cogl-context.h"
G_BEGIN_DECLS
/**
* SECTION:cogl-texture-rectangle
* @short_description: Functions for creating and manipulating rectangle
* textures for use with non-normalized coordinates.
*
* These functions allow low-level "rectangle" textures to be allocated.
* These textures are never constrained to power-of-two sizes but they
* also don't support having a mipmap and can only be wrapped with
* %COGL_PIPELINE_WRAP_MODE_CLAMP_TO_EDGE.
*
* The most notable difference between rectangle textures and 2D
* textures is that rectangle textures are sampled using un-normalized
* texture coordinates, so instead of using coordinates (0,0) and
* (1,1) to map to the top-left and bottom right corners of the
* texture you would instead use (0,0) and (width,height).
*
* The use of non-normalized coordinates can be particularly
* convenient when writing glsl shaders that use a texture as a lookup
* table since you don't need to upload separate uniforms to map
* normalized coordinates to texels.
*
* If you want to sample from a rectangle texture from GLSL you should
* use the sampler2DRect sampler type.
*
* Applications wanting to use #CoglTextureRectangle should first check
* for the %COGL_FEATURE_ID_TEXTURE_RECTANGLE feature using
* cogl_has_feature().
*/
typedef struct _CoglTextureRectangle CoglTextureRectangle;
#define COGL_TEXTURE_RECTANGLE(X) ((CoglTextureRectangle *)X)
#define cogl_is_texture_rectangle cogl_is_texture_rectangle_EXP
/**
* cogl_is_texture_rectangle:
* @object: A #CoglObject
*
* Gets whether the given object references an existing
* #CoglTextureRectangle object.
*
* Return value: %TRUE if the object references a
* #CoglTextureRectangle, %FALSE otherwise.
*/
gboolean
cogl_is_texture_rectangle (void *object);
#define cogl_texture_rectangle_new_with_size \
cogl_texture_rectangle_new_with_size_EXP
/**
* cogl_texture_rectangle_new_with_size:
* @context: A #CoglContext pointer
* @width: The texture width to allocate
* @height: The texture height to allocate
* @internal_format: The desired internal texture format
* @error: An optional GError pointer for reporting exceptions
*
* Allocates a new #CoglRectangle texture with a given @width, @height
* and @internal_format. This texture is a low-level texture that
* the GPU can sample from directly unlike high-level textures such
* as #CoglTexture2DSliced and #CoglAtlasTexture.
*
* <note>If you want to sample from a rectangle texture from GLSL you
* should use the sampler2DRect sampler type.</note>
*
* <note>Applications wanting to use #CoglTextureRectangle should
* first check for the %COGL_FEATURE_ID_TEXTURE_RECTANGLE feature
* using cogl_has_feature().</note>
*
* Returns: A pointer to a newly allocated #CoglRectangle texture
* or if the size was too large or there wasn't enough memory
* %NULL is returned and @error set.
*
* Since: 1.10
* Stability: unstable
*/
CoglTextureRectangle *
cogl_texture_rectangle_new_with_size (CoglContext *ctx,
int width,
int height,
CoglPixelFormat internal_format,
GError **error);
G_END_DECLS
#endif /* __COGL_TEXURE_RECTANGLE_H */