/*
 * 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_TOON_H__
#define __BSDF_TOON_H__

CCL_NAMESPACE_BEGIN

typedef ccl_addr_space struct ToonBsdf {
	SHADER_CLOSURE_BASE;

	float3 N;
	float size;
	float smooth;
} ToonBsdf;

/* DIFFUSE TOON */

ccl_device int bsdf_diffuse_toon_setup(ToonBsdf *bsdf)
{
	bsdf->type = CLOSURE_BSDF_DIFFUSE_TOON_ID;
	bsdf->size = saturate(bsdf->size);
	bsdf->smooth = saturate(bsdf->smooth);

	return SD_BSDF|SD_BSDF_HAS_EVAL;
}

ccl_device bool bsdf_toon_merge(const ShaderClosure *a, const ShaderClosure *b)
{
	const ToonBsdf *bsdf_a = (const ToonBsdf*)a;
	const ToonBsdf *bsdf_b = (const ToonBsdf*)b;

	return (isequal_float3(bsdf_a->N, bsdf_b->N)) &&
	       (bsdf_a->size == bsdf_b->size) &&
		   (bsdf_a->smooth == bsdf_b->smooth);
}

ccl_device float3 bsdf_toon_get_intensity(float max_angle, float smooth, float angle)
{
	float is;

	if(angle < max_angle)
		is = 1.0f;
	else if(angle < (max_angle + smooth) && smooth != 0.0f)
		is = (1.0f - (angle - max_angle)/smooth);
	else
		is = 0.0f;
	
	return make_float3(is, is, is);
}

ccl_device float bsdf_toon_get_sample_angle(float max_angle, float smooth)
{
	return fminf(max_angle + smooth, M_PI_2_F);
}

ccl_device float3 bsdf_diffuse_toon_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
	const ToonBsdf *bsdf = (const ToonBsdf*)sc;
	float max_angle = bsdf->size*M_PI_2_F;
	float smooth = bsdf->smooth*M_PI_2_F;
	float angle = safe_acosf(fmaxf(dot(bsdf->N, omega_in), 0.0f));

	float3 eval = bsdf_toon_get_intensity(max_angle, smooth, angle);
	
	if(eval.x > 0.0f) {
		float sample_angle = bsdf_toon_get_sample_angle(max_angle, smooth);

		*pdf = 0.5f * M_1_PI_F / (1.0f - cosf(sample_angle));
		return *pdf * eval;
	}

	return make_float3(0.0f, 0.0f, 0.0f);
}

ccl_device float3 bsdf_diffuse_toon_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_toon_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 ToonBsdf *bsdf = (const ToonBsdf*)sc;
	float max_angle = bsdf->size*M_PI_2_F;
	float smooth = bsdf->smooth*M_PI_2_F;
	float sample_angle = bsdf_toon_get_sample_angle(max_angle, smooth);
	float angle = sample_angle*randu;

	if(sample_angle > 0.0f) {
		sample_uniform_cone(bsdf->N, sample_angle, randu, randv, omega_in, pdf);

		if(dot(Ng, *omega_in) > 0.0f) {
			*eval = *pdf * bsdf_toon_get_intensity(max_angle, smooth, angle);

#ifdef __RAY_DIFFERENTIALS__
			// TODO: find a better approximation for the bounce
			*domega_in_dx = (2.0f * dot(bsdf->N, dIdx)) * bsdf->N - dIdx;
			*domega_in_dy = (2.0f * dot(bsdf->N, dIdy)) * bsdf->N - dIdy;
#endif
		}
		else
			*pdf = 0.0f;
	}

	return LABEL_REFLECT | LABEL_DIFFUSE;

}

/* GLOSSY TOON */

ccl_device int bsdf_glossy_toon_setup(ToonBsdf *bsdf)
{
	bsdf->type = CLOSURE_BSDF_GLOSSY_TOON_ID;
	bsdf->size = saturate(bsdf->size);
	bsdf->smooth = saturate(bsdf->smooth);

	return SD_BSDF|SD_BSDF_HAS_EVAL;
}

ccl_device float3 bsdf_glossy_toon_eval_reflect(const ShaderClosure *sc, const float3 I, const float3 omega_in, float *pdf)
{
	const ToonBsdf *bsdf = (const ToonBsdf*)sc;
	float max_angle = bsdf->size*M_PI_2_F;
	float smooth = bsdf->smooth*M_PI_2_F;
	float cosNI = dot(bsdf->N, omega_in);
	float cosNO = dot(bsdf->N, I);
	
	if(cosNI > 0 && cosNO > 0) {
		/* reflect the view vector */
		float3 R = (2 * cosNO) * bsdf->N - I;
		float cosRI = dot(R, omega_in);

		float angle = safe_acosf(fmaxf(cosRI, 0.0f));

		float3 eval = bsdf_toon_get_intensity(max_angle, smooth, angle);
		float sample_angle = bsdf_toon_get_sample_angle(max_angle, smooth);

		*pdf = 0.5f * M_1_PI_F / (1.0f - cosf(sample_angle));
		return *pdf * eval;
	}
	
	return make_float3(0.0f, 0.0f, 0.0f);
}

ccl_device float3 bsdf_glossy_toon_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_glossy_toon_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 ToonBsdf *bsdf = (const ToonBsdf*)sc;
	float max_angle = bsdf->size*M_PI_2_F;
	float smooth = bsdf->smooth*M_PI_2_F;
	float cosNO = dot(bsdf->N, I);
	
	if(cosNO > 0) {
		/* reflect the view vector */
		float3 R = (2 * cosNO) * bsdf->N - I;

		float sample_angle = bsdf_toon_get_sample_angle(max_angle, smooth);
		float angle = sample_angle*randu;

		sample_uniform_cone(R, sample_angle, randu, randv, omega_in, pdf);

		if(dot(Ng, *omega_in) > 0.0f) {
			float cosNI = dot(bsdf->N, *omega_in);

			/* make sure the direction we chose is still in the right hemisphere */
			if(cosNI > 0) {
				*eval = *pdf * bsdf_toon_get_intensity(max_angle, smooth, angle);

#ifdef __RAY_DIFFERENTIALS__
				*domega_in_dx = (2 * dot(bsdf->N, dIdx)) * bsdf->N - dIdx;
				*domega_in_dy = (2 * dot(bsdf->N, dIdy)) * bsdf->N - dIdy;
#endif
			}
			else
				*pdf = 0.0f;
		}
		else
			*pdf = 0.0f;
	}

	return LABEL_GLOSSY | LABEL_REFLECT;
}

CCL_NAMESPACE_END

#endif /* __BSDF_TOON_H__ */

