Introduction - If you have any usage issues, please Google them yourself
Delay rendering, the first screen for N-and render the same size as a buffer texture, the next thing to render the texture, the general use of FBO, render time, the normal end of each pixel value, position, texture information N, respectively, rendering a texture to this. This is the first rendering. Then, when the second rendering, the texture before the value obtained by calculating the input value as a light to calculate the light.