Lab 5Built on WebGL

Textures & Sampling

Wrap, filter and mip a texture, and see what each sampler setting actually costs you.

What you should come away with: Why a texture looks wrong at a distance, and what mipmapping is really trading away.

Assumes: Coordinate Spaces. It will still make sense without it, but that one comes first.

orientation marker
tile edge

mipmaps on

Start here

Not sure where to start? Any of these sets the controls to something worth looking at.

Minification

Trilinear: bilinear in the two nearest levels, then blended between them. No shimmer and no seams — the usual default, and the most expensive of the five.

Magnification

Bilinear blend between the four nearest texels — soft edges up close.

Wrap

horizontal (S)

vertical (T)

Coordinates

tiles6.0

offset0.00

UVs outside 0…1 are what wrap modes decide about. Push the offset with clamp selected and the edge texel smears into a stripe — that is CLAMP_TO_EDGE doing exactly what it says.

Move any control and this becomes a link you can share — the address bar follows what you do.

What the sampler is doing

texture: 256²
mip levels: 9
tiles across: 6.0
wrap: R / R

The far end of this plane compresses hundreds of texels into one pixel. A sampler with no mip chain has to pick one of them and the choice changes every frame you move — which is the shimmer. A mipmap is simply the same image pre-shrunk nine times, so there is always a level where one texel is about one pixel. It costs a third more memory and removes an entire class of artefact, which is why it is almost always the right default.