Visuals

Visuals define render expressions. They do not mutate simulation state.

visual WaterDefault for Liquid + LbmD3Q7 {
    color {
        let moving = self.fE + self.fW + self.fN + self.fS + self.fU + self.fD;
        let pooled = clamp(self.density, 0.0, 1.0);

        rgba(0.04, 0.24 + pooled * 0.24, 0.58 + moving * 0.10, 0.86)
    }
}

Visuals are attached by the simulation:

visualize Water with WaterDefault;

color is a derived render value, not a stored simulation field. A visual can be bound only to a model that composes every property in the visual’s for signature.

A reused model can bring its published appearance. A local visualize binding can override that appearance without changing its imported behavior schedule. Camera, slices and infinite grid guides belong to the viewer, not the visual definition.