Sliced Textures

## Sliced Textures Sliced Textures — Functions for creating and manipulating 2D meta textures that may internally be comprised of multiple 2D textures with power-of-two sizes. |

## Synopsis

                        CoglTexture2DSliced;
    CoglTexture2DSliced * cogl_texture_2d_sliced_new_with_size
                                                            (CoglContext *ctx,
                                                             unsigned int width,
                                                             unsigned int height,
                                                             int max_waste,
                                                             CoglPixelFormat internal_format,
                                                             GError **error);
    gboolean            cogl_is_texture_2d_sliced           (void *object);

## Description

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.

## Details

### CoglTexture2DSliced

    typedef struct _CoglTexture2DSliced CoglTexture2DSliced;

### cogl_texture_2d_sliced_new_with_size ()

    CoglTexture2DSliced * cogl_texture_2d_sliced_new_with_size
                                                            (CoglContext *ctx,
                                                             unsigned int width,
                                                             unsigned int height,
                                                             int max_waste,
                                                             CoglPixelFormat internal_format,
                                                             GError **error);

Creates a CoglTexture2DSliced that may internally be comprised of 1 or more CoglTexture2D textures with power-of-two sizes. `max_waste` is used as a threshold for recursively slicing the right-most or bottom-most slices into smaller power-of-two sizes until the wasted padding at the bottom and right of the power-of-two textures is less than specified.

`ctx` : | A CoglContext
`width` : | The virtual width of your sliced texture.
`height` : | The virtual height of your sliced texture.
`max_waste` : | The threshold of how wide a strip of wasted texels are allowed in the non-power-of-two textures before they must be sliced to reduce the amount of waste.
`internal_format` : | The format of the texture
`error` : | A GError for exceptions.
Returns : | A newly allocated CoglTexture2DSliced or if there was an error allocating any of the internal slices `NULL` is returned and `error` is updated.

Since 1.10

Stability Level: Unstable

### cogl_is_texture_2d_sliced ()

    gboolean            cogl_is_texture_2d_sliced           (void *object);

Gets whether the given object references a CoglTexture2dSliced.

`object` : | A CoglObject pointer
Returns : | `TRUE` if the object references a CoglTexture2dSliced and `FALSE` otherwise.

Since 1.10

Stability Level: Unstable