Quote from Vordwann on August 12, 2012, 2:32 pm

wrathofmobius wrote:

Vertex textures are very weird textures that shouldn't exist. They look exactly like their good counterparts in Hammer, but once you run the map, you may notice that the lighting is very weird. That is because the lighting of the texture has to do with how far away you are from it. This creates some very weird lighting effects.
I'll just repeat it again: NEVER USE VERTEX TEXTURES!

ChickenMobile wrote:

Vertex textures... why are they even there?

Vertex textures, for those who don't know quite how they work, are compiled using the VertexLitGeneric shader, which is used for models in the Source engine, not brushes.

My best guess for vertex textures are that they are what the faces of animated destruction props are UV mapped to. The hammer editor has an option to export to a .dxf file, which can be imported to 3D/CAD programs.

The faces must retain texture information, so when you bring them back into the Source engine, they can reference different vertex textures. Valve most likely used this method when creating props for the Wheatley chapters (and a few for overgrown/reconstructing) when walls that seemed like normal brushwork were actually animated meshes that crumbled, using a physics/destruction plugin in 3D animation software.

This is also supported by the fact that the faces created by using a destruction modifier on a model in a 3D animation program have warped UV maps, but still all reference a single texture, most likely still the vertex texture from the source engine. This is why, when you look at the parts of the broken tiles in the cracks, after the animation plays in-game, the texture seems warped because it is a default UV map (created by the physics/destruction plugin) that has not been modified to perfectly fit with the original sides of the exported brushes from Hammer.

Conclusion: My hypothesis is that vertex textures are the materials Valve has their animated destruction props reference for texture info because vertex textures are better suited for models, not world geometry.

"BUT VORDWANN, WHY DO WE HAVE TO SEE THEM IN THE TEXTURE BROWSER IF THEY'RE ONLY FOR MODELS?!?!?!"

VertexLitGeneric (yes, that's why they're called vertex textures) may well be a material shader for models only, but because these are applied to world geometry so it can be exported, it's more practical and convenient to have them in the texture browser in Hammer. Also, because the same vertex textures are used for several different animated destruction props, it wouldn't make sense to just hide the same texture in many different directories in the packed models, and instead it saves space and time to put it in with the Hammer-accessable texture directory.

Additionally, you don't see any vertex textures for Old Aperture materials because there are no animated destruction props for using the materials in the underground area.