二次曲面，其功能是能够创建二次物体。通过OpenGL基于屏幕像素块所覆盖的区域对每一块覆盖的范围值进行计算，然后在RGBA模式中,OpenGL用该值与Alpha值相乘。-conicoid, and its function is to create two objects. Adoption of OpenGL-based screen pixel block area covered for each one covering the value calculated, and then RG