bsdf_diffuse.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 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 
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 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
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*/

#ifndef __BSDF_DIFFUSE_H__
#define __BSDF_DIFFUSE_H__

CCL_NAMESPACE_BEGIN

/* DIFFUSE */

typedef struct BsdfDiffuseClosure {
    //float3 m_N;
} BsdfDiffuseClosure;

__device void bsdf_diffuse_setup(ShaderData *sd, ShaderClosure *sc)
{
    sc->type = CLOSURE_BSDF_DIFFUSE_ID;
    sd->flag |= SD_BSDF|SD_BSDF_HAS_EVAL;
}

__device void bsdf_diffuse_blur(ShaderClosure *sc, float roughness)
{
}

__device float3 bsdf_diffuse_eval_reflect(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
    float3 m_N = sd->N;

    float cos_pi = fmaxf(dot(m_N, omega_in), 0.0f) * M_1_PI_F;
    *pdf = cos_pi;
    return make_float3(cos_pi, cos_pi, cos_pi);
}

__device float3 bsdf_diffuse_eval_transmit(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
    return make_float3(0.0f, 0.0f, 0.0f);
}

__device float bsdf_diffuse_albedo(const ShaderData *sd, const ShaderClosure *sc, const float3 I)
{
    return 1.0f;
}

__device int bsdf_diffuse_sample(const ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
{
    float3 m_N = sd->N;

    // distribution over the hemisphere
    sample_cos_hemisphere(m_N, randu, randv, omega_in, pdf);

    if(dot(sd->Ng, *omega_in) > 0.0f) {
        *eval = make_float3(*pdf, *pdf, *pdf);
#ifdef __RAY_DIFFERENTIALS__
        // TODO: find a better approximation for the diffuse bounce
        *domega_in_dx = (2 * dot(m_N, sd->dI.dx)) * m_N - sd->dI.dx;
        *domega_in_dy = (2 * dot(m_N, sd->dI.dy)) * m_N - sd->dI.dy;
        *domega_in_dx *= 125.0f;
        *domega_in_dy *= 125.0f;
#endif
    }
    else
        *pdf = 0.0f;
    
    return LABEL_REFLECT|LABEL_DIFFUSE;
}

/* TRANSLUCENT */

typedef struct BsdfTranslucentClosure {
    //float3 m_N;
} BsdfTranslucentClosure;

__device void bsdf_translucent_setup(ShaderData *sd, ShaderClosure *sc)
{
    sc->type = CLOSURE_BSDF_TRANSLUCENT_ID;
    sd->flag |= SD_BSDF|SD_BSDF_HAS_EVAL;
}

__device void bsdf_translucent_blur(ShaderClosure *sc, float roughness)
{
}

__device float3 bsdf_translucent_eval_reflect(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
    return make_float3(0.0f, 0.0f, 0.0f);
}

__device float3 bsdf_translucent_eval_transmit(const ShaderData *sd, const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
    float3 m_N = sd->N;

    float cos_pi = fmaxf(-dot(m_N, omega_in), 0.0f) * M_1_PI_F;
    *pdf = cos_pi;
    return make_float3 (cos_pi, cos_pi, cos_pi);
}

__device float bsdf_translucent_albedo(const ShaderData *sd, const ShaderClosure *sc, const float3 I)
{
    return 1.0f;
}

__device int bsdf_translucent_sample(const ShaderData *sd, const ShaderClosure *sc, float randu, float randv, float3 *eval, float3 *omega_in, float3 *domega_in_dx, float3 *domega_in_dy, float *pdf)
{
    float3 m_N = sd->N;

    // we are viewing the surface from the right side - send a ray out with cosine
    // distribution over the hemisphere
    sample_cos_hemisphere (-m_N, randu, randv, omega_in, pdf);
    if(dot(sd->Ng, *omega_in) < 0) {
        *eval = make_float3(*pdf, *pdf, *pdf);
#ifdef __RAY_DIFFERENTIALS__
        // TODO: find a better approximation for the diffuse bounce
        *domega_in_dx = (2 * dot(m_N, sd->dI.dx)) * m_N - sd->dI.dx;
        *domega_in_dy = (2 * dot(m_N, sd->dI.dy)) * m_N - sd->dI.dy;
        *domega_in_dx *= -125.0f;
        *domega_in_dy *= -125.0f;
#endif
    } else
        *pdf = 0;

    return LABEL_TRANSMIT|LABEL_DIFFUSE;
}

CCL_NAMESPACE_END

#endif /* __BSDF_DIFFUSE_H__ */