Hum. My shader knowledge is limited but if anything I thought it'd be higher (I seem to recall some modern cards being able to do 64bit floats). You possibly have to turn it on (or off) since working with fixed points is inherently faster. For this application I sense that speed is not your issue. Immediately I see- http://www.opengl.org/discussion_boards/showthread.php/170053-Shader-floating-point-precision [^] And http://stackoverflow.com/questions/4414041/what-is-the-precision-of-highp-floats-in-glsl-es-2-0-for-iphone-ipod-touch-ipad[^] as being relevant. (There should be a corally in directx as well). Hope this helps.