   Colors
  1) Generally, what's the point in giving a vertex a color component (RGBA) if it's ultimately the texture mapping that defines the mesh's appearance/color/look?2) Also, I remember reading somewhere about color masks (colors used as masks), in general, how are those used when rendering a mesh? I mean I know how they are used when rendering sprites and filtering colors to the color/frame buffer but with a mesh? I have no clue.[Edited by - 16bit_port on May 8, 2010 11:43:13 AM]
  To answer 1)Depends on what your doing, if your working with densly tesselated meshes you can use the colours of the vertices as the diffuse instead of using a map with texture coordinates.Back in the old days, like talking quake 2 days, they used to colour the verts to create psychadelic textures, but not many people do that now cause noones that impressed by it anymore.To answer 2)Not sure what you mean.   ;  You can use the verticies mixed with the texture colour to help break up texture repeats. It acts as extra low-frequency 3-channel noise.You could use the vertex colours to mix in effects for individual meshes -- mud, blood, smoke-blackening etc. Cheap, easy and doesn't need the fillrate overhead of decals.The RGB values provide a way to pass extra data in -- one example use is to use those values to control the blending of multiple textures across a landscape. These days you'd probably do it with arbitrary vertex attributes, but on older drivers it provided extra data channels.If you normally colour the mesh in white/grey shades, you could colour various parts of meshes in other colours to indicate properties such as selection.You can do cheap lighting effects -- normally your mech's mesh is grey coloured, but you know which verticies are near the guns and when it opens fire, you change the colour of those verticies. Instance "muzzleflash" lighting effects without needing to add an actual lightsource.It allows you to re-use a texture adding a different appearance; a greenish tinge can be added to the brickwork of a bridge in the areas near the water. A single brickwork texture can be stone or brick depending on if you have a greyish or reddish polygon underlying it.;  In my software 3D engine I use vertex colors to store lighting effects in. Sometimes I also use the vertex colors to highlight certain parts of the mesh by darkening the surrounding vertices' colors.   