Rewrite `!physics` computation code as an OpenGL compute shader?

[jonathanhogg]

This would require OpenGL 4.3, but would obviously allow for significant performance gains. One could, perhaps, retain the CPU implementation and only attempt use of a compute shader if ARB_compute_shader is present.

More on compute shaders here:

https://www.khronos.org/opengl/wiki/Compute_Shader

and a moderngl example here:

https://github.com/moderngl/moderngl/blob/main/examples/compute_shader_ssbo.py