Fast Way To Determine If All Pixels In Opengl Depth Buffer Were Drawn At Least Once?

Fast Way To Determine If All Pixels In Opengl Depth Buffer Were Drawn At Least Once?

Hello, I am programming a FPS game and I simply want to make it faster. I tried a lot of things, from which few of them worked. My testing map has 15k vertexes and 26k triangles, and I am using partitioning space by X*Y*Z orthogonal cubes. Thats fine cause it works. Next thing that helped a lot was to order partitions by metric from partition where I am and display them from nearest, which caused OpenGl to not overdraw it so much. Also I use face culling and my own per-triangle frustum clipping, and also overdraw check that makes it sure that same triangle is rendered only once. Also before loading a map, the triangle lists of each partition are ordered by texture to minimalize need of switching glEnd and glBegin, which caused big slowdown. Also, I tried arranging triangles into triangle strips, but they suck arse, and also I tried using VBOs instead glBegin and glEnd, but it didnt helped that much as internet promised. My next, yet undone idea is to compute all this stuff just when the player position and rotation changes, and if not just render it as before without any computations.

 

Anyway, in every tic I count number of triangles being actually drawn. As a testing map I use Hell Gate from Quake III (that one with crazy mouth in a room, if somebody knows that one ) loaded from exported .obj file. When I am on the end of map and looking outside (in the mouth), 36 triangles are being drawn, which seems fair to me. However, turning by 180 degrees causes me to look INSIDE the map and my frustum to contain nearly all partitions, and 22k triangles from 26k are displayed. Now I get to my idea - display few partitions, then CHECK IF ALL PIXELS WERE DISPLAYED, if not, display some more partitions, and so on. That could make it really fast, cause it would cut of everything excpet the first room. Problém is that extracting depth buffer and checking all the 1920x1080 of that little guys is so slow that it would be contraproductive (proven by try).

 

So my question is - is there actually a FAST way how to check if all pixels are rendered at least once? (= if the depth value is not 127 anywhere) I did like 3-hours research which didnt found answer. Also, if people here will say "no" it will encourage me in writing my own rasterization (at least I will have totally full control).