text: /*
   * 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.
   * * Neither the name of Sony Pictures Imageworks nor the names of its
   *   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
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef __BSDF_DIFFUSE_RAMP_H__
  #define __BSDF_DIFFUSE_RAMP_H__
  
  CCL_NAMESPACE_BEGIN
  
  ccl_device float3 bsdf_diffuse_ramp_get_color(const ShaderClosure *sc, 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(ShaderClosure *sc)
  {
  	sc->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 colors[8], const float3 I, const float3 omega_in, float *pdf)
  {
  	float3 N = sc->N;
  
  	float cos_pi = fmaxf(dot(N, omega_in), 0.0f);
  	*pdf = cos_pi * M_1_PI_F;
  	return bsdf_diffuse_ramp_get_color(sc, colors, cos_pi) * M_1_PI_F;
  }
  
  ccl_device float3 bsdf_diffuse_ramp_eval_transmit(const ShaderClosure *sc, const float3 colors[8], 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, const float3 colors[8], 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)
  {
  	float3 N = sc->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(sc, 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;
  }
  
  CCL_NAMESPACE_END
  
  #endif /* __BSDF_DIFFUSE_RAMP_H__ */
  