direct_lighting_rl.h

/*
 * Fermat
 *
 * Copyright (c) 2017-2019, NVIDIA CORPORATION. All rights reserved.
 * 
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 * 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 the NVIDIA CORPORATION 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
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 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include <lights.h>
#include <clustered_rl.h>
#include <vtl_mesh_view.h>
#include <spatial_hash.h>



struct DirectLightingRL
{
    typedef AdaptiveClusteredRLView RLMap;

    static const uint32 INVALID_SLOT    = 0xFFFFFFFF;
    static const uint32 INVALID_SAMPLE  = 0xFFFFFFFF;

    FERMAT_HOST_DEVICE
    DirectLightingRL() {}

    FERMAT_HOST_DEVICE
    DirectLightingRL(
        RLMap       _rl,
        VTLMeshView _vtls) :
        vtl_rl(_rl), vtls(_vtls) {}

    FERMAT_DEVICE
    uint32 preprocess_vertex(
        const RenderingContextView& renderer,
        const EyeVertex&    ev,
        const uint32        pixel,
        const uint32        bounce,
        const bool          is_secondary_diffuse,
        const float         cone_radius,
        const cugar::Bbox3f scene_bbox)
    {
        // compute a spatial hash
        const float cone_scale   = 32.0f;
        const float filter_scale = is_secondary_diffuse ? 0.2f : 1.5f;

        const uint32 base_dim   = (is_secondary_diffuse ? 0 : renderer.instance) * 6;
        const uint32 random_set = cugar::hash(pixel + renderer.res_x * renderer.res_y * bounce);

        const float jitter[6] = {
            cugar::randfloat( base_dim + 0, random_set ),
            cugar::randfloat( base_dim + 1, random_set ),
            cugar::randfloat( base_dim + 2, random_set ),
            cugar::randfloat( base_dim + 3, random_set ),
            cugar::randfloat( base_dim + 4, random_set ),
            cugar::randfloat( base_dim + 5, random_set ),
        };

        const float bbox_delta = cugar::max_comp( scene_bbox[1] - scene_bbox[0] );

        const uint64 shading_key = spatial_hash(
            pixel,
            ev.geom.position,
            dot(ev.in, ev.geom.normal_s) > 0.0f ? ev.geom.normal_s : -ev.geom.normal_s,
            ev.geom.tangent,
            ev.geom.binormal,
            scene_bbox,
            jitter,
            cugar::min( cone_radius * cone_scale, bbox_delta * 0.05f ),
            //cone_radius * cone_scale,
            filter_scale);

        return vtl_rl.find_slot(shading_key);
    }

    FERMAT_DEVICE
    uint32 sample(
        const uint32        nee_slot,
        const float         z[3],
        VertexGeometryId*   light_vertex,
        VertexGeometry*     light_vertex_geom,
        float*              light_pdf,
        Edf*                light_edf)
    {
        // sample the light source surface
        //
        if (nee_slot != INVALID_SLOT)
        {
            uint32 vtl_cluster;

            // 1. use the clustered-RL to sample a VPL
            float  vtl_pdf;
            uint32 vtl_idx = vtl_rl.sample( nee_slot, z[2], &vtl_pdf, &vtl_cluster );

            // 2. sample the selected VTL uniformly
            vtls.sample( vtl_idx, cugar::Vector2f(z[0],z[1]), &light_vertex->prim_id, &light_vertex->uv, light_vertex_geom, light_pdf, light_edf );
            
            // 3. multiply by the RL-sampling pdf
            *light_pdf *= vtl_pdf;

            return vtl_cluster;
        }
        else
        {
            const uint32 vtl_idx = cugar::quantize( z[2], vtls.vtl_count() );

            // sample the selected VTL uniformly
            vtls.sample( vtl_idx, cugar::Vector2f(z[0],z[1]), &light_vertex->prim_id, &light_vertex->uv, light_vertex_geom, light_pdf, light_edf );

            return INVALID_SAMPLE;
        }
    }

    FERMAT_DEVICE
    void map(
        const uint32            prev_nee_slot,
        const uint32            triId,
        const cugar::Vector2f   uv,
        const VertexGeometry    light_vertex_geom,
        float*                  light_pdf,
        Edf*                    light_edf)
    {
        const uint32 vtl_idx = vtls.map(triId, uv, light_vertex_geom, light_pdf, light_edf);
        if (prev_nee_slot != uint32(-1) && vtl_idx != uint32(-1))
        {
            // multiply by the clustered-RL pdf
            *light_pdf *= vtl_rl.pdf( prev_nee_slot, vtl_idx );
        }
    }

    FERMAT_DEVICE
    void update(
        const uint32            nee_slot,
        const uint32            nee_cluster,
        const cugar::Vector3f   w,
        const bool              occluded)
    {
        // update the NEE RL pdfs
        if (nee_cluster != INVALID_SAMPLE)
        {
            const float new_value = cugar::max_comp(w.xyz()) * (occluded == false ? 1.0f : 0.0f);

            vtl_rl.update(nee_slot, nee_cluster, new_value);
        }
    }

    RLMap       vtl_rl;
    VTLMeshView vtls;
};