blender/intern/cycles/kernel/shaders/node_rgb_curves.osl

/*
 * Copyright 2011-2013 Blender Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "stdosl.h"
#include "oslutil.h"

float ramp_lookup(color ramp[], float at, int component)
{
	int table_size = arraylength(ramp);

	if (at < 0.0 || at > 1.0) {
		float t0, dy;
		if (at < 0.0) {
			t0 = ramp[0][component];
			dy = t0 - ramp[1][component];
			at = -at;
		}
		else {
			t0 = ramp[table_size - 1][component];
			dy = t0 - ramp[table_size - 2][component];
			at = at - 1.0;
		}
		return t0 + dy * at * (table_size - 1);
	}

	float f = clamp(at, 0.0, 1.0) * (table_size - 1);

	/* clamp int as well in case of NaN */
	int i = (int)f;
	if (i < 0) i = 0;
	if (i >= table_size) i = table_size - 1;
	float t = f - (float)i;

	float result = ramp[i][component];

	if (t > 0.0)
		result = (1.0 - t) * result + t * ramp[i + 1][component];
	
	return result;
}

shader node_rgb_curves(
	color ramp[] = {0.0},
	float min_x = 0.0,
	float max_x = 1.0,

	color ColorIn = 0.0,
	float Fac = 0.0,
	output color ColorOut = 0.0)
{
	color c = (ColorIn - color(min_x, min_x, min_x)) / (max_x - min_x);

	ColorOut[0] = ramp_lookup(ramp, c[0], 0);
	ColorOut[1] = ramp_lookup(ramp, c[1], 1);
	ColorOut[2] = ramp_lookup(ramp, c[2], 2);

	ColorOut = mix(ColorIn, ColorOut, Fac);
}