renderer.set_shader_program(&shprog, &shdata);
renderer.set_texture("source", &color_buf, &nearest_sampler);
renderer.set_texture("curve", &curve, &linear_sampler);
renderer.set_shader_program(&shprog, &shdata);
renderer.set_texture("source", &color_buf, &nearest_sampler);
renderer.set_texture("curve", &curve, &linear_sampler);