blender/intern/cycles/kernel/shaders/node_light_falloff.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"

shader node_light_falloff(
	float Strength = 0.0,
	float Smooth = 0.0,
	output float Quadratic = 0.0,
	output float Linear = 0.0,
	output float Constant = 0.0)
{
	float ray_length = 0.0;
	float strength = Strength;
	getattribute("path:ray_length", ray_length);

	if (Smooth > 0.0) {
		float squared = ray_length * ray_length;
		strength *= squared / (Smooth + squared);
	}

	/* Quadratic */ 
	Quadratic = strength;
	
	/* Linear */
	Linear = (strength * ray_length);

	/* Constant */
	Constant = (strength * ray_length * ray_length);
}