reflection probes and volumetrics in 1.80

2023-09-25

Did you know reflection probes?

Cubemap. Environment map. Reflection probe. Reflection capture. They go by many names, but they are all essentially just a fancy way of saying "a full 360 degree panoramic image". Although that's not quite accurate. 360 degree panoramic images are usually equirectangular projections of a sphere to a 2D image, whereas cubemaps are simply 6 images of the scene taken in 6 different directions, that can map to faces of a cube. To view the "panorama" you must then simply exist within the cube and gaze at it.

A video rendered in Blender 1.80 showing a reflective sphere moving over a cube, and then the cube itself moving. The moving cube also moves in the reflection.

Blender started out as a scanline renderer, with no type of raytracing. This was intentional as raytracers were known to be slow, and Blender was made for quick day to day animation studio work. You can read about it in the Blender 1.5 manual!. Anyways, since scanline renderers scan lines instead of tracing rays, they can't do real reflections. But you don't need real reflections to make something look reflective!

Reflections must be one of the most faked effects in computer graphics, as doing it the *proper* way would involve actually reflecting all camera rays hitting the reflective surface, or rendering the entire scene again from the perspective of a mirror. For realtime graphics (games) you can get away with environment mapping most of the time

Another cool thing is volumetric fog.

The 3D text "Punoflip" rotating in a dark void, reflecting a picture of a city at night and being lit from behind with a spot light that casts volumetric haze around the text.