CHECKS
THE BOX'S MAIN HELP:
This function generates a checkered pattern.
FU (input):
This must be a float. The default is 4. This control the number of checks.
FV (input):
This must be a float. The default is 4. This control the number of checks.
U (input):
This must be a float. The default is state->tex_list[0].x
V (input):
This must be a float. The default is state->tex_list[0].y
OUT (output):
This function generates a checkered pattern.