The paints of Cauldron3D.Paint in RGBA, four bytes a pixel, for a picture drawn in full colour (Cauldron3D.Render.draw/3 with :palette).

An indexed texture's colours come from its own palette, or the picture's. Light 128 is a texture's own colours; light scales red, green and blue alike, or each by its own amount where a paint gives {r, g, b} light. A texel of the setup's clear index is alpha 0, which the overlays leave out. A surface is an RGBA texture already lit.

A setup with a tint has each pixel's colour and alpha multiplied by it; where it also has an alpha_test, a pixel whose own alpha is below the test is alpha 0 first.

{:warp, ...}'s :amplitude and :wavelength may each be {s, t}: the move along s (by the sine of t) and the move along t (by the sine of s).

Besides Cauldron3D.Paint's paints:

• {:skybox, faces} — a sky at no distance from six RGBA textures, faces a map with :front (looking along +x), :back, :left (+y), :right, :up (+z) and :down, each seen from inside the box with up toward +z (:up and :down with their top toward +x)
• {:lit, paint, lighting} — paint (with the setup's tint) and, added to it, the light of each of lighting.lights (%{origin:, radius:, colour: {r, g, b}}, and for a spot light fov: in degrees with axes: {forward, right, up}) on a flat surface of normal lighting.normal: at the pixel's place p in a perspective view, with l the light's origin less p, each channel of the texel of lighting.texture at the paint's place plus lighting.offset (alpha 0 where it is colour lighting.clear) times max(normal · l / |l|, 0) * max(1 - |l|² / radius², 0) (times 1 - x² - y² for a spot, x and y being p's place across and up the light's view over its distance along forward times tan(fov / 2), and nothing behind it) times the colour times the texel's alpha, each light's share held at 0 or above