blender/intern/cycles/kernel/svm/svm_closure.h

/*
 * Copyright 2011, Blender Foundation.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

CCL_NAMESPACE_BEGIN

/* Closure Nodes */

__device void svm_node_glossy_setup(ShaderData *sd, ShaderClosure *sc, int type, float eta, float roughness, bool refract)
{
	if(type == CLOSURE_BSDF_REFRACTION_ID) {
		if(refract)
			bsdf_refraction_setup(sd, sc, eta);
		else
			bsdf_reflection_setup(sd, sc);
	}
	else if(type == CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID) {
		bsdf_microfacet_beckmann_setup(sd, sc, roughness, eta, refract);
	}
	else
		bsdf_microfacet_ggx_setup(sd, sc, roughness, eta, refract);
}

__device_inline ShaderClosure *svm_node_closure_get(ShaderData *sd)
{
#ifdef __MULTI_CLOSURE__
	ShaderClosure *sc = &sd->closure[sd->num_closure];

	if(sd->num_closure < MAX_CLOSURE)
		sd->num_closure++;

	return sc;
#else
	return &sd->closure;
#endif
}

__device_inline void svm_node_closure_set_mix_weight(ShaderClosure *sc, float mix_weight)
{
#ifdef __MULTI_CLOSURE__
	sc->weight *= mix_weight;
	sc->sample_weight = fabsf(average(sc->weight));
#endif
}

__device void svm_node_closure_bsdf(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, float randb, int path_flag)
{
	uint type, param1_offset, param2_offset;

#ifdef __MULTI_CLOSURE__
	uint mix_weight_offset;
	decode_node_uchar4(node.y, &type, &param1_offset, &param2_offset, &mix_weight_offset);
	float mix_weight = (stack_valid(mix_weight_offset)? stack_load_float(stack, mix_weight_offset): 1.0f);

	if(mix_weight == 0.0f)
		return;
#else
	decode_node_uchar4(node.y, &type, &param1_offset, &param2_offset, NULL);
	float mix_weight = 1.0f;
#endif

	float param1 = (stack_valid(param1_offset))? stack_load_float(stack, param1_offset): __int_as_float(node.z);
	float param2 = (stack_valid(param2_offset))? stack_load_float(stack, param2_offset): __int_as_float(node.w);

	switch(type) {
		case CLOSURE_BSDF_DIFFUSE_ID: {
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);

			float roughness = param1;
			if(roughness == 0.0f)
				bsdf_diffuse_setup(sd, sc);
			else
				bsdf_oren_nayar_setup(sd, sc, roughness);
			break;
		}
		case CLOSURE_BSDF_TRANSLUCENT_ID: {
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);
			bsdf_translucent_setup(sd, sc);
			break;
		}
		case CLOSURE_BSDF_TRANSPARENT_ID: {
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);
			bsdf_transparent_setup(sd, sc);
			break;
		}
		case CLOSURE_BSDF_REFLECTION_ID:
		case CLOSURE_BSDF_MICROFACET_GGX_ID:
		case CLOSURE_BSDF_MICROFACET_BECKMANN_ID: {
#ifdef __CAUSTICS_TRICKS__
			if(kernel_data.integrator.no_caustics && (path_flag & PATH_RAY_DIFFUSE))
				break;
#endif
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);

			float roughness = param1;

			/* setup bsdf */
			if(type == CLOSURE_BSDF_REFLECTION_ID)
				bsdf_reflection_setup(sd, sc);
			else if(type == CLOSURE_BSDF_MICROFACET_BECKMANN_ID)
				bsdf_microfacet_beckmann_setup(sd, sc, roughness, 1.0f, false);
			else
				bsdf_microfacet_ggx_setup(sd, sc, roughness, 1.0f, false);

			break;
		}
		case CLOSURE_BSDF_REFRACTION_ID:
		case CLOSURE_BSDF_MICROFACET_GGX_REFRACTION_ID:
		case CLOSURE_BSDF_MICROFACET_BECKMANN_REFRACTION_ID: {
#ifdef __CAUSTICS_TRICKS__
			if(kernel_data.integrator.no_caustics && (path_flag & PATH_RAY_DIFFUSE))
				break;
#endif
			/* index of refraction */
			float eta = fmaxf(param2, 1.0f + 1e-5f);
			eta = (sd->flag & SD_BACKFACING)? 1.0f/eta: eta;

			/* fresnel */
			float cosNO = dot(sd->N, sd->I);
			float fresnel = fresnel_dielectric_cos(cosNO, eta);
			float roughness = param1;

#ifdef __MULTI_CLOSURE__
			/* reflection */
			ShaderClosure *sc = svm_node_closure_get(sd);

			float3 weight = sc->weight;
			float sample_weight = sc->sample_weight;

			svm_node_closure_set_mix_weight(sc, mix_weight*fresnel);
			svm_node_glossy_setup(sd, sc, type, eta, roughness, false);

			/* refraction */
			sc = svm_node_closure_get(sd);

			sc->weight = weight;
			sc->sample_weight = sample_weight;

			svm_node_closure_set_mix_weight(sc, mix_weight*(1.0f - fresnel));
			svm_node_glossy_setup(sd, sc, type, eta, roughness, true);
#else
			ShaderClosure *sc = svm_node_closure_get(sd);

			bool refract = (randb > fresnel);

			svm_node_closure_set_mix_weight(sc, mix_weight);
			svm_node_glossy_setup(sd, sc, type, eta, roughness, refract);
#endif

			break;
		}
#ifdef __DPDU__
		case CLOSURE_BSDF_WARD_ID: {
#ifdef __CAUSTICS_TRICKS__
			if(kernel_data.integrator.no_caustics && (path_flag & PATH_RAY_DIFFUSE))
				break;
#endif
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);

			float roughness_u = param1;
			float roughness_v = param2;

			bsdf_ward_setup(sd, sc, normalize(sd->dPdu), roughness_u, roughness_v);
			break;
		}
#endif
		case CLOSURE_BSDF_ASHIKHMIN_VELVET_ID: {
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);

			/* sigma */
			float sigma = clamp(param1, 0.0f, 1.0f);
			bsdf_ashikhmin_velvet_setup(sd, sc, sigma);
			break;
		}
		default:
			break;
	}
}

__device void svm_node_closure_volume(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node, int path_flag)
{
	uint type, param1_offset, param2_offset;

#ifdef __MULTI_CLOSURE__
	uint mix_weight_offset;
	decode_node_uchar4(node.y, &type, &param1_offset, &param2_offset, &mix_weight_offset);
	float mix_weight = (stack_valid(mix_weight_offset)? stack_load_float(stack, mix_weight_offset): 1.0f);

	if(mix_weight == 0.0f)
		return;
#else
	decode_node_uchar4(node.y, &type, &param1_offset, &param2_offset, NULL);
	float mix_weight = 1.0f;
#endif

	float param1 = (stack_valid(param1_offset))? stack_load_float(stack, param1_offset): __int_as_float(node.z);
	//float param2 = (stack_valid(param2_offset))? stack_load_float(stack, param2_offset): __int_as_float(node.w);

	switch(type) {
		case CLOSURE_VOLUME_TRANSPARENT_ID: {
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);

			float density = param1;
			volume_transparent_setup(sd, sc, density);
			break;
		}
		case CLOSURE_VOLUME_ISOTROPIC_ID: {
			ShaderClosure *sc = svm_node_closure_get(sd);
			svm_node_closure_set_mix_weight(sc, mix_weight);

			float density = param1;
			volume_isotropic_setup(sd, sc, density);
			break;
		}
		default:
			break;
	}
}

__device void svm_node_closure_emission(ShaderData *sd, float *stack, uint4 node)
{
#ifdef __MULTI_CLOSURE__
	uint mix_weight_offset = node.y;

	if(stack_valid(mix_weight_offset)) {
		float mix_weight = stack_load_float(stack, mix_weight_offset);

		if(mix_weight == 0.0f)
			return;

		ShaderClosure *sc = svm_node_closure_get(sd);
		sc->weight *= mix_weight;
		sc->type = CLOSURE_EMISSION_ID;
	}
	else {
		ShaderClosure *sc = svm_node_closure_get(sd);
		sc->type = CLOSURE_EMISSION_ID;
	}

#else
	ShaderClosure *sc = &sd->closure;
	sc->type = CLOSURE_EMISSION_ID;
#endif

	sd->flag |= SD_EMISSION;
}

__device void svm_node_closure_background(ShaderData *sd, float *stack, uint4 node)
{
#ifdef __MULTI_CLOSURE__
	uint mix_weight_offset = node.y;

	if(stack_valid(mix_weight_offset)) {
		float mix_weight = stack_load_float(stack, mix_weight_offset);

		if(mix_weight == 0.0f)
			return;

		ShaderClosure *sc = svm_node_closure_get(sd);
		sc->weight *= mix_weight;
		sc->type = CLOSURE_BACKGROUND_ID;
	}
	else {
		ShaderClosure *sc = svm_node_closure_get(sd);
		sc->type = CLOSURE_BACKGROUND_ID;
	}

#else
	ShaderClosure *sc = &sd->closure;
	sc->type = CLOSURE_BACKGROUND_ID;
#endif
}

__device void svm_node_closure_holdout(ShaderData *sd, float *stack, uint4 node)
{
#ifdef __MULTI_CLOSURE__
	uint mix_weight_offset = node.y;

	if(stack_valid(mix_weight_offset)) {
		float mix_weight = stack_load_float(stack, mix_weight_offset);

		if(mix_weight == 0.0f)
			return;

		ShaderClosure *sc = svm_node_closure_get(sd);
		sc->weight = make_float3(mix_weight, mix_weight, mix_weight);
		sc->type = CLOSURE_HOLDOUT_ID;
	}
	else {
		ShaderClosure *sc = svm_node_closure_get(sd);
		sc->weight = make_float3(1.0f, 1.0f, 1.0f);
		sc->type = CLOSURE_HOLDOUT_ID;
	}
#else
	ShaderClosure *sc = &sd->closure;
	sc->type = CLOSURE_HOLDOUT_ID;
#endif

	sd->flag |= SD_HOLDOUT;
}

/* Closure Nodes */

__device_inline void svm_node_closure_store_weight(ShaderData *sd, float3 weight)
{
#ifdef __MULTI_CLOSURE__
	sd->closure[sd->num_closure].weight = weight;
#else
	sd->closure.weight = weight;
#endif
}

__device void svm_node_closure_set_weight(ShaderData *sd, uint r, uint g, uint b)
{
	float3 weight = make_float3(__int_as_float(r), __int_as_float(g), __int_as_float(b));
	svm_node_closure_store_weight(sd, weight);
}

__device void svm_node_emission_set_weight_total(KernelGlobals *kg, ShaderData *sd, uint r, uint g, uint b)
{
	float3 weight = make_float3(__int_as_float(r), __int_as_float(g), __int_as_float(b));

	if(sd->object != ~0)
		weight /= object_surface_area(kg, sd->object);

	svm_node_closure_store_weight(sd, weight);
}

__device void svm_node_closure_weight(ShaderData *sd, float *stack, uint weight_offset)
{
	float3 weight = stack_load_float3(stack, weight_offset);

	svm_node_closure_store_weight(sd, weight);
}

__device void svm_node_emission_weight(KernelGlobals *kg, ShaderData *sd, float *stack, uint4 node)
{
	uint color_offset = node.y;
	uint strength_offset = node.z;
	uint total_power = node.w;

	float strength = stack_load_float(stack, strength_offset);
	float3 weight = stack_load_float3(stack, color_offset)*strength;

	if(total_power && sd->object != ~0)
		weight /= object_surface_area(kg, sd->object);

	svm_node_closure_store_weight(sd, weight);
}

__device void svm_node_mix_closure(ShaderData *sd, float *stack,
	uint4 node, int *offset, float *randb)
{
#ifdef __MULTI_CLOSURE__
	/* fetch weight from blend input, previous mix closures,
	 * and write to stack to be used by closure nodes later */
	uint weight_offset, in_weight_offset, weight1_offset, weight2_offset;
	decode_node_uchar4(node.y, &weight_offset, &in_weight_offset, &weight1_offset, &weight2_offset);

	float weight = stack_load_float(stack, weight_offset);
	float in_weight = (stack_valid(in_weight_offset))? stack_load_float(stack, in_weight_offset): 1.0f;

	if(stack_valid(weight1_offset))
		stack_store_float(stack, weight1_offset, in_weight*(1.0f - weight));
	if(stack_valid(weight2_offset))
		stack_store_float(stack, weight2_offset, in_weight*weight);
#else
	/* pick a closure and make the random number uniform over 0..1 again.
	 * closure 1 starts on the next node, for closure 2 the start is at an
	 * offset from the current node, so we jump */
	uint weight_offset = node.y;
	uint node_jump = node.z;
	float weight = stack_load_float(stack, weight_offset);
	weight = clamp(weight, 0.0f, 1.0f);

	if(*randb < weight) {
		*offset += node_jump;
		*randb = *randb/weight;
	}
	else
		*randb = (*randb - weight)/(1.0f - weight);
#endif
}

__device void svm_node_add_closure(ShaderData *sd, float *stack, uint unused,
	uint node_jump, int *offset, float *randb, float *closure_weight)
{
#ifdef __MULTI_CLOSURE__
	/* nothing to do, handled in compiler */
#else
	/* pick one of the two closures with probability 0.5. sampling quality
	 * is not going to be great, for that we'd need to evaluate the weights
	 * of the two closures being added */
	float weight = 0.5f;

	if(*randb < weight) {
		*offset += node_jump;
		*randb = *randb/weight;
	}
	else
		*randb = (*randb - weight)/(1.0f - weight);
	
	*closure_weight *= 2.0f;
#endif
}

CCL_NAMESPACE_END