Chapter 10 -- Alpha Blending

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Chapter 10

As Microsoft Direct3D renders a scene, it can integrate color information from several sources: vertex color, the current material, texture maps, and the color previously written to the render target. Rather than simply choosing the color from only one of these locations, Direct3D can blend several of these colors. A factor called alpha can be used to indicate how the blending should be weighted. Alpha values can be stored in vertices, materials, and texture maps. Alpha is usually treated as a measure of opacity; that is, an alpha value of 0 means full transparency, an alpha value of 1 means full opacity, and alpha values between 0 and 1 mean some level of semitransparency. By using alpha blending, you can create interesting and realistic visual effects.