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Rectangle textures (non-normalized coordinates)Rectangle textures (non-normalized coordinates) — 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().
CoglTextureRectangle * cogl_texture_rectangle_new_with_size (CoglContext *ctx,int width,int height,CoglPixelFormat internal_format,CoglError **error);
Allocates a new CoglTextureRectangle 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.
width, height) where width
and height are the width and height of the texture.COGL_FEATURE_ID_TEXTURE_RECTANGLE feature
using cogl_has_feature().ctx |
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 CoglError pointer for reporting exceptions |
A pointer to a newly allocated
CoglTextureRectangle texture or if the size was too large
or there wasn't enough memory NULL is returned and error
set.
[transfer full]
Since 1.10
Stability Level: Unstable
CoglTextureRectangle * cogl_texture_rectangle_new_from_bitmap (CoglBitmap *bitmap,CoglPixelFormat internal_format,CoglError **error);
Allocates a new CoglTextureRectangle texture which will be
initialized with the pixel data from bitmap
. Internally the data
will be stored in the format given by 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.
width, height) where width
and height are the width and height of the texture.COGL_FEATURE_ID_TEXTURE_RECTANGLE feature
using cogl_has_feature().bitmap |
||
internal_format |
the CoglPixelFormat to use for the GPU storage of the texture |
|
error |
A return location for a CoglError or |
A pointer to a newly allocated
CoglTextureRectangle texture or if the size was too large
or there wasn't enough memory NULL is returned and error
set.
[transfer full]
Since 2.0
Stability Level: Unstable
CoglBool
cogl_is_texture_rectangle (void *object);
Gets whether the given object references an existing CoglTextureRectangle object.