OpenGL中的绝大多数特效都与某些类型的（色彩）混合有关。混色的定义为，将某个象素的颜色和已绘制在屏幕上与其对应的象素颜色相互结合。至于如何结合这两个颜色则依赖于颜色的alpha通道的分量值，以及/或者所使用的混色函数。Alpha通常是位于颜色值末尾的第4个颜色组成分量。前面这些课我们都是用GL_RGB来指定颜色的三个分量。相应的GL_RGBA可以指定alpha分量的值。更进一步，我们可以使用glColor4f()来代替glColor3f()。-OpenGL in the vast majority of effects are related to certain types of (color) mixed about. Blending is defined as the color of a pixel and has drawn on the screen and its corresponding pixel color combination. As for how to combine these two colors is dependent on the color of the alpha channel of the sub-value, and/or the use of blending functions. Alpha is usually the color value at the end of the first four color composition of components. We are all in front of the class to specify the color with GL_RGB three components. GL_RGBA corresponding alpha component values can be specified. Furthermore, we can use glColor4f () instead of glColor3f ().