Blending - Introduction to 3D Game Programming with DirectX 9.0 - page 121

Chapter 7
Blending
In this chapter we examine a technique called blending that allows us to
blend (combine) pixels that we are currently rasterizing with pixels that
have been previously rasterized to the same pixel locations. In other
words, we blend primitives over previously drawn primitives. This
technique allows us to achieve a variety of effects (in particular,
transparency).
Objectives
To understand how blending works and how to use it
To learn about the different blend modes that Direct3D supports
To find out how the alpha component can be used to control the
transparency of a primitive
7.1 The Blending Equation
Consider Figure 7.1, where we have a red teapot drawn in front of a
wooden crate background.
Figure 7.1: An opaque
teapot
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