PLatLongEnvSphere.h

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#pragma once
 
#include "Core/Intersection/PBasicSphere.h"
#include "Math/TVector2.h"
#include "Math/TVector3.h"
#include "Math/Geometry/TAABB3D.h"
#include "Math/Transform/StaticRigidTransform.h"
 
#include <array>
 
namespace ph
{
 
class PLatLongEnvSphere : public PBasicSphere
{
    // TODO: currently not fully time aware
public:
    explicit PLatLongEnvSphere(real radius);
 
    PLatLongEnvSphere(
        real radius, 
        const math::StaticRigidTransform* localToWorld,
        const math::StaticRigidTransform* worldToLocal);
 
    bool isIntersecting(const Ray& ray, HitProbe& probe) const override;
    bool isOccluding(const Ray& ray) const override;
 
    void calcHitDetail(
        const Ray& ray,
        HitProbe&  probe,
        HitDetail* out_detail) const override;
 
    void calcPosPdf(PrimitivePosPdfQuery& query) const override;
 
    void genPosSample(
        PrimitivePosSampleQuery& query,
        SampleFlow& sampleFlow,
        HitProbe& probe) const override;
 
    bool mayOverlapVolume(const math::AABB3D& volume) const override;
    math::AABB3D calcAABB() const override;
    real calcExtendedArea() const override;
 
private:
    void genPosSampleWithObservationPos(
        const math::Vector2R& latLong01,
        real latLong01Pdf,
        PrimitivePosSampleQuery& query,
        HitProbe& probe) const;
 
    void genPosSampleWithoutObservationPos(
        const math::Vector2R& latLong01,
        real latLong01Pdf,
        PrimitivePosSampleQuery& query,
        SampleFlow& sampleFlow,
        HitProbe& probe) const;
 
    void calcPosPdfWithObservationPos(
        const math::Vector2R& latLong01,
        real latLong01Pdf,
        PrimitivePosPdfQuery& query) const;
 
    bool latLong01ToSurface(
        const math::Vector2R& latLong01,
        const math::Vector3R& observationPos,
        math::Vector3R* out_surface,
        math::Vector3R* out_unitObservationDir) const;
 
    void latLong01ToSurface(
        const math::Vector2R& latLong01,
        const std::array<real, 2>& uniformSample,
        math::Vector3R* out_surface,
        math::Vector3R* out_unitObservationDir,
        real* out_pdfA) const;
 
    const math::StaticRigidTransform* m_localToWorld;
    const math::StaticRigidTransform* m_worldToLocal;
    math::Vector3R m_worldOrigin;
};
 
inline bool PLatLongEnvSphere::mayOverlapVolume(const math::AABB3D& volume) const
{
    // Rather than transforming `volume` to local space, we transform the sphere to world space 
    // instead. Under static rigid transform the sphere shape is rotational invariant, we can 
    // inversely translate `volume` and test against the sphere at the origin
    auto effectiveVolume = volume.getTranslated(m_worldOrigin.negate());
    return PBasicSphere::mayOverlapVolume(effectiveVolume);
}
 
inline math::AABB3D PLatLongEnvSphere::calcAABB() const
{
    // Under static rigid transform, only translation will matter to the AABB of a sphere
    return PBasicSphere::calcAABB().translate(m_worldOrigin);
}
 
inline real PLatLongEnvSphere::calcExtendedArea() const
{
    // Does not change under rigid transform
    return PBasicSphere::calcExtendedArea();
}
 
}// end namespace ph