Pro OpenGL ES for iOS

174 CHAPTER 6: Will It Blend?^

Figure 6-3. Blending full intensities of red and blue

Now it’s time for another experiment of sorts. Take the code from the previous example,

set both alphas to 0.5, and reset the blend function back to the traditional values for

transparency:

glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);

After you run this modified code, take note of the combined color, and notice that the

further square is blue at -4.0 away and is also the first to be rendered, with the red one

as the second. Now reverse the order of the colors that are drawn, and run. What’s

wrong? You should get something like Figure 6-4.