bsdf_diffuse_ramp.h

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/*
 * Adapted from Open Shading Language with this license:
 *
 * Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
 * All Rights Reserved.
 *
 * Modifications Copyright 2012, Blender Foundation.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
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 *   contributors may be used to endorse or promote products derived from
 *   this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 */
 
#ifndef __BSDF_DIFFUSE_RAMP_H__
#define __BSDF_DIFFUSE_RAMP_H__
 
CCL_NAMESPACE_BEGIN
 
#ifdef __OSL__
 
typedef ccl_addr_space struct DiffuseRampBsdf {
  SHADER_CLOSURE_BASE;
 
  float3 *colors;
} DiffuseRampBsdf;
 
static_assert(sizeof(ShaderClosure) >= sizeof(DiffuseRampBsdf), "DiffuseRampBsdf is too large!");
 
ccl_device float3 bsdf_diffuse_ramp_get_color(const float3 colors[8], float pos)
{
  int MAXCOLORS = 8;
 
  float npos = pos * (float)(MAXCOLORS - 1);
  int ipos = float_to_int(npos);
  if (ipos < 0)
    return colors[0];
  if (ipos >= (MAXCOLORS - 1))
    return colors[MAXCOLORS - 1];
  float offset = npos - (float)ipos;
  return colors[ipos] * (1.0f - offset) + colors[ipos + 1] * offset;
}
 
ccl_device int bsdf_diffuse_ramp_setup(DiffuseRampBsdf *bsdf)
{
  bsdf->type = CLOSURE_BSDF_DIFFUSE_RAMP_ID;
  return SD_BSDF | SD_BSDF_HAS_EVAL;
}
 
ccl_device void bsdf_diffuse_ramp_blur(ShaderClosure *sc, float roughness)
{
}
 
ccl_device float3 bsdf_diffuse_ramp_eval_reflect(const ShaderClosure *sc,
                                                 const float3 I,
                                                 const float3 omega_in,
                                                 float *pdf)
{
  const DiffuseRampBsdf *bsdf = (const DiffuseRampBsdf *)sc;
  float3 N = bsdf->N;
 
  float cos_pi = fmaxf(dot(N, omega_in), 0.0f);
  *pdf = cos_pi * M_1_PI_F;
  return bsdf_diffuse_ramp_get_color(bsdf->colors, cos_pi) * M_1_PI_F;
}
 
ccl_device float3 bsdf_diffuse_ramp_eval_transmit(const ShaderClosure *sc,
                                                  const float3 I,
                                                  const float3 omega_in,
                                                  float *pdf)
{
  return make_float3(0.0f, 0.0f, 0.0f);
}
 
ccl_device int bsdf_diffuse_ramp_sample(const ShaderClosure *sc,
                                        float3 Ng,
                                        float3 I,
                                        float3 dIdx,
                                        float3 dIdy,
                                        float randu,
                                        float randv,
                                        float3 *eval,
                                        float3 *omega_in,
                                        float3 *domega_in_dx,
                                        float3 *domega_in_dy,
                                        float *pdf)
{
  const DiffuseRampBsdf *bsdf = (const DiffuseRampBsdf *)sc;
  float3 N = bsdf->N;
 
  // distribution over the hemisphere
  sample_cos_hemisphere(N, randu, randv, omega_in, pdf);
 
  if (dot(Ng, *omega_in) > 0.0f) {
    *eval = bsdf_diffuse_ramp_get_color(bsdf->colors, *pdf * M_PI_F) * M_1_PI_F;
#  ifdef __RAY_DIFFERENTIALS__
    *domega_in_dx = (2 * dot(N, dIdx)) * N - dIdx;
    *domega_in_dy = (2 * dot(N, dIdy)) * N - dIdy;
#  endif
  }
  else
    *pdf = 0.0f;
 
  return LABEL_REFLECT | LABEL_DIFFUSE;
}
 
#endif /* __OSL__ */
 
CCL_NAMESPACE_END
 
#endif /* __BSDF_DIFFUSE_RAMP_H__ */