svm_closure.h

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/*
 * 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