OpenGL 4.2 Atomic Counters: Rasterization Pattern, Helper for Rendering Optimization (Windows, Linux)

2013/10/31 JeGX

Article index:

This demo is an update of the first atomic counters demo I published last year. No big changes except this new demo is for GLSL Hacker and then is available for Windows and Linux and maybe in a decade for OS X (bad luck, OpenGL 4.2 is required and OS X just got OpenGL 4.1) 😉

This demo of atomic counters allows to show three uses:

1 – the rasterization pattern on several different GPUs
2 – the number of vertices processed to render a triangular mesh
3 – the number of fragments processed to render a triangular mesh

The demos of this article have been coded with GLSL Hacker and you can find all source codes in the Code Sample Pack in the moon3d/gl-420-atomic_counters/ folder. You can download GLSL Hacker from this page.

As usual, the GLSL programs are not specific to GLSL Hacker. You can use them in any OpenGL/WebGL application with minor changes only (shader inputs).

All demos are based on Lua programming language and modules are used to simplify the main code.

1 – Rasterization pattern

Atomic counters allows to show in which order the pixels are renderer. The following images show how a 256×256-pixel quad is renderer on GeForce GTX 660, 680, 780 and on Radeon HD 6970.
The order of rendering corresponds to the color: black zones are rendered first then the red ones.

GeForce GTX 680 + R325.25, Linux Mint 13