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Cogl 2.0 Reference Manual | ![]() |
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Top | Description |
Sliced TexturesSliced Textures — Functions for creating and manipulating 2D meta textures that may internally be comprised of multiple 2D textures with power-of-two sizes. |
CoglTexture2DSliced; CoglTexture2DSliced * cogl_texture_2d_sliced_new_with_size (CoglContext *ctx
,int width
,int height
,int max_waste
,CoglPixelFormat internal_format
); CoglTexture2DSliced * cogl_texture_2d_sliced_new_from_file (CoglContext *ctx
,const char *filename
,int max_waste
,CoglPixelFormat internal_format
,CoglError **error
); CoglTexture2DSliced * cogl_texture_2d_sliced_new_from_data (CoglContext *ctx
,int width
,int height
,int max_waste
,CoglPixelFormat format
,CoglPixelFormat internal_format
,int rowstride
,const uint8_t *data
,CoglError **error
); CoglTexture2DSliced * cogl_texture_2d_sliced_new_from_bitmap (CoglBitmap *bmp
,int max_waste
,CoglPixelFormat internal_format
,CoglError **error
); CoglBool cogl_is_texture_2d_sliced (void *object
);
These functions allow high-level meta textures (See the CoglMetaTexture interface) to be allocated that may internally be comprised of multiple 2D texture "slices" with power-of-two sizes.
This API can be useful when working with GPUs that don't have native support for non-power-of-two textures or if you want to load a texture that is larger than the GPUs maximum texture size limits.
The algorithm for slicing works by first trying to map a virtual size to the next larger power-of-two size and then seeing how many wasted pixels that would result in. For example if you have a virtual texture that's 259 texels wide, the next pot size = 512 and the amount of waste would be 253 texels. If the amount of waste is above a max-waste threshold then we would next slice that texture into one that's 256 texels and then looking at how many more texels remain unallocated after that we choose the next power-of-two size. For the example of a 259 texel image that would mean having a 256 texel wide texture, leaving 3 texels unallocated so we'd then create a 4 texel wide texture - now there is only one texel of waste. The algorithm continues to slice the right most textures until the amount of waste is less than or equal to a specfied max-waste threshold. The same logic for slicing from left to right is also applied from top to bottom.
CoglTexture2DSliced * cogl_texture_2d_sliced_new_with_size (CoglContext *ctx
,int width
,int height
,int max_waste
,CoglPixelFormat internal_format
);
Creates a CoglTexture2DSliced that may internally be comprised of 1 or more CoglTexture2D textures depending on GPU limitations. For example if the GPU only supports power-of-two sized textures then a sliced texture will turn a non-power-of-two size into a combination of smaller power-of-two sized textures. If the requested texture size is larger than is supported by the hardware then the texture will be sliced into smaller textures that can be accessed by the hardware.
max_waste
is used as a threshold for recursively slicing the
right-most or bottom-most slices into smaller sizes until the
wasted padding at the bottom and right of the textures is less than
specified. A negative max_waste
will disable slicing.
The storage for the texture is not allocated before this function
returns. You can call cogl_texture_allocate()
to explicitly
allocate the underlying storage or let Cogl automatically allocate
storage lazily.
max_waste
value is given. If the given virtual texture size size
is larger than is supported by the hardware but slicing is disabled
the texture size would be too large to handle.
|
A CoglContext |
|
The virtual width of your sliced texture. |
|
The virtual height of your sliced texture. |
|
The threshold of how wide a strip of wasted texels are allowed along the right and bottom textures before they must be sliced to reduce the amount of waste. A negative can be passed to disable slicing. |
|
The format of the texture |
Returns : |
A new CoglTexture2DSliced object with no storage allocated yet. |
Since 1.10
Stability Level: Unstable
CoglTexture2DSliced * cogl_texture_2d_sliced_new_from_file (CoglContext *ctx
,const char *filename
,int max_waste
,CoglPixelFormat internal_format
,CoglError **error
);
Creates a CoglTexture2DSliced from an image file.
A CoglTexture2DSliced may internally be comprised of 1 or more CoglTexture2D textures depending on GPU limitations. For example if the GPU only supports power-of-two sized textures then a sliced texture will turn a non-power-of-two size into a combination of smaller power-of-two sized textures. If the requested texture size is larger than is supported by the hardware then the texture will be sliced into smaller textures that can be accessed by the hardware.
max_waste
is used as a threshold for recursively slicing the
right-most or bottom-most slices into smaller sizes until the
wasted padding at the bottom and right of the textures is less than
specified. A negative max_waste
will disable slicing.
max_waste
value is given. If the given virtual texture size is
larger than is supported by the hardware but slicing is disabled
the texture size would be too large to handle.
|
A CoglContext |
|
the file to load |
|
The threshold of how wide a strip of wasted texels are allowed along the right and bottom textures before they must be sliced to reduce the amount of waste. A negative can be passed to disable slicing. |
|
the CoglPixelFormat to use for the GPU storage of the
texture. If COGL_PIXEL_FORMAT_ANY is given then a premultiplied
format similar to the format of the source data will be used. The
default blending equations of Cogl expect premultiplied color data;
the main use of passing a non-premultiplied format here is if you
have non-premultiplied source data and are going to adjust the blend
mode (see cogl_material_set_blend() ) or use the data for something
other than straight blending. |
|
A CoglError to catch exceptional errors or NULL
|
Returns : |
A newly created CoglTexture2DSliced or NULL on
failure and error will be updated. |
Since 1.16
CoglTexture2DSliced * cogl_texture_2d_sliced_new_from_data (CoglContext *ctx
,int width
,int height
,int max_waste
,CoglPixelFormat format
,CoglPixelFormat internal_format
,int rowstride
,const uint8_t *data
,CoglError **error
);
Creates a new CoglTexture2DSliced texture based on data residing in memory.
A CoglTexture2DSliced may internally be comprised of 1 or more CoglTexture2D textures depending on GPU limitations. For example if the GPU only supports power-of-two sized textures then a sliced texture will turn a non-power-of-two size into a combination of smaller power-of-two sized textures. If the requested texture size is larger than is supported by the hardware then the texture will be sliced into smaller textures that can be accessed by the hardware.
max_waste
is used as a threshold for recursively slicing the
right-most or bottom-most slices into smaller sizes until the
wasted padding at the bottom and right of the textures is less than
specified. A negative max_waste
will disable slicing.
max_waste
value is given. If the given virtual texture size is
larger than is supported by the hardware but slicing is disabled
the texture size would be too large to handle.
|
width of texture in pixels |
|
height of texture in pixels |
|
the CoglPixelFormat the buffer is stored in in RAM |
|
The threshold of how wide a strip of wasted texels are allowed along the right and bottom textures before they must be sliced to reduce the amount of waste. A negative can be passed to disable slicing. |
|
the CoglPixelFormat to use for the GPU storage of the
texture. If COGL_PIXEL_FORMAT_ANY is given then a premultiplied
format similar to the format of the source data will be used. The
default blending equations of Cogl expect premultiplied color data;
the main use of passing a non-premultiplied format here is if you
have non-premultiplied source data and are going to adjust the blend
mode (see cogl_material_set_blend() ) or use the data for something
other than straight blending. |
|
the memory offset in bytes between the start of each
row in data . A value of 0 will make Cogl automatically
calculate rowstride from width and format . |
|
pointer the memory region where the source buffer resides |
|
A CoglError to catch exceptional errors or NULL
|
Returns : |
A newly created CoglTexture2DSliced or NULL on
failure and error will be updated. |
Since 1.16
CoglTexture2DSliced * cogl_texture_2d_sliced_new_from_bitmap (CoglBitmap *bmp
,int max_waste
,CoglPixelFormat internal_format
,CoglError **error
);
Creates a new CoglTexture2DSliced texture based on data residing in a bitmap.
A CoglTexture2DSliced may internally be comprised of 1 or more CoglTexture2D textures depending on GPU limitations. For example if the GPU only supports power-of-two sized textures then a sliced texture will turn a non-power-of-two size into a combination of smaller power-of-two sized textures. If the requested texture size is larger than is supported by the hardware then the texture will be sliced into smaller textures that can be accessed by the hardware.
max_waste
is used as a threshold for recursively slicing the
right-most or bottom-most slices into smaller sizes until the
wasted padding at the bottom and right of the textures is less than
specified. A negative max_waste
will disable slicing.
max_waste
value is given. If the given virtual texture size is
larger than is supported by the hardware but slicing is disabled
the texture size would be too large to handle.
|
A CoglBitmap |
|
The threshold of how wide a strip of wasted texels are allowed along the right and bottom textures before they must be sliced to reduce the amount of waste. A negative can be passed to disable slicing. |
|
the CoglPixelFormat to use for the GPU storage of the
texture. If COGL_PIXEL_FORMAT_ANY is given then a premultiplied
format similar to the format of the source data will be used. The
default blending equations of Cogl expect premultiplied color data;
the main use of passing a non-premultiplied format here is if you
have non-premultiplied source data and are going to adjust the blend
mode (see cogl_material_set_blend() ) or use the data for something
other than straight blending. |
|
A CoglError to catch exceptional errors or NULL
|
Returns : |
A newly created CoglTexture2DSliced or NULL on
failure and error will be updated. |
Since 1.16
CoglBool cogl_is_texture_2d_sliced (void *object
);
Gets whether the given object references a CoglTexture2DSliced.
|
A CoglObject pointer |
Returns : |
TRUE if the object references a CoglTexture2DSliced
and FALSE otherwise. |
Since 1.10
Stability Level: Unstable