Voxel
A voxel, or volumetric pixel, is a three-dimensional analogy of a pixel. Voxel files end in ".VXL".Voxels may be virtually any colour (assuming the colour is utilised in the palette of the game or voxel editor)and can use surface normals. Voxels may also be animated with the use of an HVA file, but there are limits in the Tiberian Sun and Red Alert 2 engines as to what unit types may use certain types of animations. For example, in Tiberian Sun, an aircraft type may not utilise a turret animation.
Voxels are usually used to render vehicles and turrets in the Tiberian Sun and Red Alert 2 engines, whereas SHP files are generally used for infantry units and buildings. This is due to hard-coded restrictions in the game engines, and also because SHPs are usually of a higher in-game quality than voxels.
It is worth noting that units which are comprised of voxels will tilt while walking up a slope in the aforementioned engines, whereas an SHP unit, such as the Titan or Wolverine, will not. Voxels are generally used for the turrets of SHP buildings such as the Sentry Gun or Grand Cannon, because they allow 360 degree rotation of the turret, without the need for the facings that would be used in an SHP.
Format
[insert more info here, re: sections and stuff]
The individual voxels (in terms of volumetric pixels) are stored as a series of five values in WW's voxel format: The X, Y and Z position of the voxel, the color index, and the normal index.
The what color the color index stands for depends on the palette the voxel is displayed with; what angle a normals value indicates depends on the normals generation and the normals array value for the index.