3 Replies Latest reply on Nov 17, 2014 12:16 PM by Robert_U

    OpenGL GLSL sin, cos, and sqrt precision on Intel HD 5000

    LmMike

      What is the maximum, actual precision of the sin, cos, and sqrt functions on an Intel HD 5000? I am working with a Surface Pro 3.

       

      I have a calculation in a shader which generates a cartesian position from a WGS84 location.

       

      The result is off by about 0.00001 radians. This would seem to suggest that Intel's trig precision is the bottom of the barrel for GLSL support -- 1/100000.

       

      This function works perfectly on an ancient NVidia Geforce 8400 GS. The exact same shader, with the same inputs, produces an output with an undesirable offset.

       

      I need to know the precision to know whether I just have to avoid Intel cards entirely.

       

      I may be able to provide more info as needed, but I need to use this as a starting point.

       

      Alternatively, are there any caveats or gotchyas with Intel GLSL math, as opposed to NVidias, that someone might know of?