
1. Re: OpenGL GLSL sin, cos, and sqrt precision on Intel HD 5000
Robert_U Oct 16, 2014 7:42 AM (in response to LmMike)Hi Michael
I am looking into your questions and will report back on this thread soon.
Thanks
Robert

2. Re: OpenGL GLSL sin, cos, and sqrt precision on Intel HD 5000
LmMike Oct 16, 2014 9:22 AM (in response to Robert_U)Thanks.
I tried double precision in the shader, which only works for sqrt, and it had no effect. So that might zero it in on the cos/sin.
I actually think the float type has higher precision than the NVidia card, but I can't easily confirm that. But the ellipsoid math is producing an incorrect result.
Note that the angles are all between PI and PI. Most experiments are between 0 and PI or 0 and PI/2.

3. Re: OpenGL GLSL sin, cos, and sqrt precision on Intel HD 5000
Robert_U Nov 17, 2014 12:16 PM (in response to LmMike)Hi Michael
Yes, you are correct – double precision sin/cos functions are not present in GLSL.
Maybe ‘precise’ qualifier will help. It tells compiler not to optimize math expressions (for example, do not replace ‘x /y’ with ‘x * rcp(y)’).
Thanks
Robert