test2/intern/cycles/kernel/osl/shaders/node_light_falloff.osl

/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
 *
 * SPDX-License-Identifier: Apache-2.0 */

#include "stdcycles.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 (ray_length == FLT_MAX) {
    /* Distant lights (which have a ray_length of FLT_MAX) overflow when using most outputs of
     * the light falloff node. So just ignore the node in that case. */
    Quadratic = strength;
    Linear = strength;
    Constant = strength;
  }
  else {
    if (Smooth > 0.0) {
      float squared = ray_length * ray_length;
      strength *= squared / (Smooth + squared);
    }

    Quadratic = strength;
    Linear = (strength * ray_length);
    Constant = (strength * ray_length * ray_length);
  }
}