ABSTRACT
This chapter presents a novel (cross-platform) solution to the alpha blending of foliage, a solution that increases the quality of a wide range of alpha- test-class renderings, giving them the appearance of true alpha blending. Application of the post-process consisted of the rendering of an orthographically projected, quadrilateral polygon mapped over the entire screen onto which peoples applied a pixel shader to actually perform the blending work. Alpha blending uses a scalar value output by the pixel shader (alpha-value) to blend a rendered fragment with the destination pixel data. When rendering the foliage color with alpha testing enabled, a suitable alpha reference value had to be chosen and peoples exposed the color-pass alpha reference value to the artists for tweaking. The solution employed for Pure was to expose the foliage color passes' clear screen color to the artists, the idea being that by adjusting the color, people could lighten the artifact until it was hardly visible.
