Alpha Textures

[AnAngelsDeath]

I'm not sure if this is the right place to post this but since it has something to do with GPU's i figured i would try it here. But what exactly are Alpha Textures ? I was reading a review on HardOCP about the new MSI N580GTX Lightning XE GPU and they were talking about Alpha Textures, and I have heard of them before, but never really have heard what they exactly are.


and again sorry if this is the wrong spot, i just really couldn't figure out where this question should go

 

[defaultluser]

Alpha = the level of transparency of the texture. You can see through a texture with transparency.

One of the most common uses of Alpha textures is to make complex things like fences and ironwork without using tons of polygons to represent them. From a distance, they look pretty good.

The fence on the left side of the picture is an alpha texture. It contains portions that are transparent, and portions that are not (the fence textures). If you looked at it completely from the side, it would have no depth - there is no geometry defining that fence. Here is what the fence texture looks like alone (the checkerboard pattern denotes transparent regions):

Other popular uses of full transparency textures include creating foliage/leaves.

You can use partial levels of transparency to create effects like windows: this is called Alpha blending, where you make the underlying textures partially visible and blended with the textures above. See the image below, where the right picture shows the red sphere alpha-blended with partial transparency.

The name Alpha comes from an "Alpha channel" that was tacked-on to the RGB pixels used in representing 3D graphics.