Struct TextureDescriptor 

pub struct TextureDescriptor {
    pub extent: Extent2D,
    pub format: PixelFormat,
    pub usage: TextureUsage,
    pub sample_count: u32,
    pub mip_levels: u32,
    pub external: Option<ExternalImageDesc>,
}

What to allocate, or what to import.

Fields

extent: Extent2D

format: PixelFormat

usage: TextureUsage

sample_count: u32

Sample count for MSAA targets. 1 means single-sampled.

mip_levels: u32

How many mip levels this texture holds. 1 is the image alone.

A chain is not made for every texture, because it costs a third again in memory and a pass of downsampling on upload, and most textures here are drawn at or above their own size where it would never be read. A caller who will minify states it, and Self::mipmapped works out how many levels that takes.

Levels past the first are filled by the backend when the texture is written, not by the caller: there is no way to hand them in, because a chain a caller built by some other rule would sample differently on the two backends and this renderer’s whole test model is that they agree.

external: Option<ExternalImageDesc>

When present, import this existing image instead of allocating.

Implementations

impl TextureDescriptor

pub fn offscreen(extent: Extent2D, format: PixelFormat) -> Self

An offscreen render target, the workhorse of the test suites.

pub fn sampled(extent: Extent2D, format: PixelFormat) -> Self

A texture only ever read by a shader.

A baked gradient ramp and an uploaded image are both this: written once from the processor, sampled many times, never drawn into. Saying so costs a backend nothing and saves it a color attachment – which is not merely tidiness on GLES, where a format can be filterable as a texture and not renderable as an attachment. Asking for a target a caller does not need is how a texture that would have worked fails to be created.

pub fn mipmapped(extent: Extent2D, format: PixelFormat) -> Self

The same, with a full mip chain.

Every level down to a single texel, which is what a caller minifying by an unknown amount needs and is only a third again in memory however far it goes – each level is a quarter of the one above, and a quarter summed forever is a third.

pub fn is_mipmapped(&self) -> bool

Whether this texture holds more than the image itself.

pub fn is_external(&self) -> bool

Whether this describes an import rather than an allocation.

Trait Implementations

impl Debug for TextureDescriptor

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.