if (width != last_width || height != last_height || num_bits != last_num_bits) {
update_texture(glsl_program_num, prefix, sampler_num);
last_width = width;
if (width != last_width || height != last_height || num_bits != last_num_bits) {
update_texture(glsl_program_num, prefix, sampler_num);
last_width = width;