reseting the grid at the beginning of every physic update, implemented with a computeshader. maybe there is a more performant way to do this, using glBufferSubData or glClearBuffer... and merging velocity and mass buffer... Mass buffer currently is used for the array_buffer as well, what makes it quite hard to merge with the velocity buffer and using it for rendering. But if we need to do a seperate array buffer later on anyways, in order to give normals to the vertex shader, this problem would be obsolete anyways. So maybe it would be a time saver to use a built in OpenGL command.