CodePudding user response:
So-called depth, pixel distance Z coordinates in the coordinate system is the distance of the observer, an area of OpenGL will have special Z values (Z value of each pixel) store, is the depth buffer, in general, we draw the graph, drawing back the cover at the front of the graphics, the order of the general drawing from the back forward, so will produce a "cover part of the" performance problems, first draw will be overwritten, and you observe only the most hidden under the module on the map, there is no meaning, depth test appears to solve the problem of cover,