emissiveMap

An emissive map is a texture used in 3D computer graphics to define which parts of a surface should appear to emit light. This is distinct from actual light sources, as emissive materials do not illuminate other objects in the scene but rather glow on their own. The map itself is typically a grayscale image where white areas represent the brightest emission, black areas represent no emission, and shades of gray represent varying degrees of light output.

When applied to a material, the emissive map dictates the color and intensity of the light emitted by specific pixels or texels of the surface. For instance, a screen on a computer monitor in a game might use an emissive map to make the display glow while the rest of the monitor casing remains dark. Similarly, warning lights or indicators on a vehicle model can be simulated using emissive maps.

The advantage of using an emissive map is that it allows for the creation of visually striking effects without the performance cost associated with real-time global illumination or numerous point lights. It's a common technique for adding details like illuminated buttons, neon signs, or glowing magical effects. The emitted color can be controlled independently of the surface's base color, allowing for a wide range of visual possibilities. Many rendering engines and game development tools support emissive maps as a standard material property.