/*
 * Adapted from Open Shading Language with this license:
 *
 * Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al.
 * All Rights Reserved.
 *
 * Modifications Copyright 2011, 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_TRANSPARENT_H__
#define __BSDF_TRANSPARENT_H__

CCL_NAMESPACE_BEGIN

ccl_device void bsdf_transparent_setup(ShaderData *sd, const float3 weight, int path_flag)
{
  /* Check cutoff weight. */
  float sample_weight = fabsf(average(weight));
  if (!(sample_weight >= CLOSURE_WEIGHT_CUTOFF)) {
    return;
  }

  if (sd->flag & SD_TRANSPARENT) {
    sd->closure_transparent_extinction += weight;

    /* Add weight to existing transparent BSDF. */
    for (int i = 0; i < sd->num_closure; i++) {
      ShaderClosure *sc = &sd->closure[i];

      if (sc->type == CLOSURE_BSDF_TRANSPARENT_ID) {
        sc->weight += weight;
        sc->sample_weight += sample_weight;
        break;
      }
    }
  }
  else {
    sd->flag |= SD_BSDF | SD_TRANSPARENT;
    sd->closure_transparent_extinction = weight;

    if (path_flag & PATH_RAY_TERMINATE) {
      /* In this case the number of closures is set to zero to disable
       * all others, but we still want to get transparency so increase
       * the number just for this. */
      sd->num_closure_left = 1;
    }

    /* Create new transparent BSDF. */
    ShaderClosure *bsdf = closure_alloc(
        sd, sizeof(ShaderClosure), CLOSURE_BSDF_TRANSPARENT_ID, weight);

    if (bsdf) {
      bsdf->sample_weight = sample_weight;
      bsdf->N = sd->N;
    }
    else if (path_flag & PATH_RAY_TERMINATE) {
      sd->num_closure_left = 0;
    }
  }
}

ccl_device float3 bsdf_transparent_eval_reflect(const ShaderClosure *sc,
                                                const float3 I,
                                                const float3 omega_in,
                                                float *pdf)
{
  return make_float3(0.0f, 0.0f, 0.0f);
}

ccl_device float3 bsdf_transparent_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_transparent_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)
{
  // only one direction is possible
  *omega_in = -I;
#ifdef __RAY_DIFFERENTIALS__
  *domega_in_dx = -dIdx;
  *domega_in_dy = -dIdy;
#endif
  *pdf = 1;
  *eval = make_float3(1, 1, 1);
  return LABEL_TRANSMIT | LABEL_TRANSPARENT;
}

CCL_NAMESPACE_END

#endif /* __BSDF_TRANSPARENT_H__ */
