opengl实例给三角形和四边形添加2种不同类型的着色方法。使用单调着色（Flat coloring）给四边形涂上固定的一种颜色。使用平滑着色（Smooth coloring）将三角形的三个顶点的不同颜色混合在一起，创建漂亮的色彩混合。-opengl examples to add two kinds of triangles and quadrilaterals of different types of coloring methods. Use of monotone color (Flat coloring) to a fixed quadrilateral painted a color. Use smooth shading (Smooth coloring) to the triangle' s three vertices of different colors mixed together, create a beautiful color mixing.