TextureFormat

Namespace: Ava3D

public enum TextureFormat

A block-compressed texture format, as the hardware stores it.

Why this exists. A texel of RGBA8 is four bytes, and a third again for its mip chain. A consumer of this control measured 58.7 Mtexels of surface across one ship, which is 224 MB by that arithmetic — and the whole of it decompresses on the card for free in one of the formats below, at a quarter to a sixth of the size. It is the largest single memory saving available anywhere in this library, and it is entirely a matter of accepting bytes that are already in the right shape.

Which format is a device question, not a preference. None of these is universal. BC is desktop and console; ETC2 is the GL ES 3.0 and WebGL 2 baseline; ASTC is where mobile went. So a caller either ships the one its target has, or ships more than one and asks — and RenderInfo.Features reports what this device took.

A format the device cannot take is decoded on the CPU and uploaded as RGBA8: larger and slower, and it says so, but never a wrong picture.

Values

Value	Description
`Rgba8`	Uncompressed RGBA, eight bits a channel. What `Texture.FromPixels` produces.
`Bc1`	BC1 / DXT1: colour and one bit of alpha, at half a byte a texel. Desktop and console.
`Bc3`	BC3 / DXT5: colour with interpolated alpha, one byte a texel.
`Bc4`	BC4: one channel, half a byte a texel. For a height field or a mask.
`Bc5`	BC5: two channels, one byte a texel. The usual home for a tangent-space normal map.
`Bc7`	BC7: colour and alpha at one byte a texel, and the best of these on desktop.
`Etc2Rgb`	ETC2 RGB: half a byte a texel. Core in GL ES 3.0, and the WebGL 2 baseline.
`Etc2Rgba`	ETC2 RGBA: one byte a texel.
`Astc4x4`	ASTC at 4×4 blocks: one byte a texel. Where mobile went.
`Astc8x8`	ASTC at 8×8 blocks: a quarter of a byte a texel.