How to Use:
Red when z=1, Green when z=-1, x range -2 to 2, y range -2 to 2 (Samples 101 times each direction)
Create function float f(float x, float y) which returns the z value to display.
If need graph outside of range you scale.
Language is GLSL.
Analytic wave equation example at https://github.com/Hitthesurf/Rendering/blob/main/3DGraph/2DxyWaveExample.txt