Rendering soft shadows with OpenGL based on planar projection method

Because projection shadows algorithm is easy to understand and implement, it plays an important role in the practical application of realistic computer graphics. In this paper, on the basis of OpenGL, we draw the shadows on the plane using projection shadows algorithm. In order to approximate soft-shadow effect, a number of points on the light source are sampled. For each of these point light sources, an image is rendered. Enable the GLBLEND function of OpenGL to blend images rendered from each sample point, then the average of these images is the image with soft shadows.