Textures

Textures

render/texture.mojo and render/texture_store.mojo. A Texture is an RGBA image with a wrap mode, a filter, a color space and an optional mip chain. A material names one by id.

three.js: Texture, wrapS, wrapT, magFilter, minFilter, generateMipmaps, colorSpace.

Make a texture

checkerboard(size, squares, first, second, wrap=REPEAT, filter=NEAREST, mipmapped=False)
texture_from(image, wrap=REPEAT, filter=NEAREST, color_space=None, mipmapped=False)
Texture(width, height, pixels, wrap=REPEAT, filter=NEAREST, color_space=SRGB, mipmapped=False)

checkerboard builds a test pattern. texture_from takes a DecodedImage from the PNG reader. Texture takes row-major RGBA bytes from the top.

Wrap

Value	A coordinate of 1.5 reads
REPEAT	The same texel as 0.5.
CLAMP	The edge texel.
MIRROR	The image reflected, so tiles meet without a seam.

Under REPEAT, coordinates 0 and 1 name the same texel. Under CLAMP they name opposite edges.

Filter

Value	Meaning
NEAREST	The texel the sample lands in. Hard edges.
BILINEAR	The four nearest texels, blended by distance.

Mipmaps

mipmapped=True builds a chain of halved copies down to one texel. Sampling then picks the level whose texels match the pixel footprint, and blends between the two nearest levels. This stops a distant surface from shimmering.

The chain costs a third more memory. It is built in premultiplied linear light.

Color space

Value	Meaning
SRGB	An image. Bytes are decoded to linear light when read. The default.
LINEAR	Data. Bytes are used as stored.
UNKNOWN_SPACE	A decoder's answer for a file it cannot interpret. A texture refuses it.

Alpha is never decoded. It is coverage, not color.

Coordinates

u runs from left to right and v from bottom to top. Rows in memory run from the top. Sampling flips once, as three.js's flipY does.

Members

Member	Meaning
sample(u, v) -> FloatColor	The color at a coordinate, level zero.
sample_level(u, v, level) -> FloatColor	Trilinear, between two mip levels.
texel(x, y) -> Color	One stored texel.
is_blank() -> Bool	The blank texture, which samples as opaque white.
validate()	Refuse a wrap, filter or color space that is none of the named values.
levels, width, height	The chain length and the base size.

TextureStore

assets.textures.add(texture) returns a TextureId. get(id) borrows it. NO_TEXTURE is the id of no texture, and samples as white.

Errors

• Dimensions must be positive, and the buffer length must match.
• A wrap, filter or color space that is none of its named values raises. The GPU upload checks again.
• A checkerboard size must divide evenly by its square count.

Why

See Why mipmaps and Why color is linear.