deformation_northstar.h

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// Copyright 2020, Hesham Wahba.
// Copyright 2020, Nova King.
// SPDX-License-Identifier: BSD-3-Clause

#pragma once

#include "utility_northstar.h"
#include "../ns_hmd.h"
#include <map>


class OpticalSystem
{
public:
        OpticalSystem(){};

        OpticalSystem(const OpticalSystem &_in);

        void
        LoadOpticalData(struct ns_eye *eye);

        Vector3
        GetEyePosition()
        {
                return eyePosition;
        }

        Vector2
        RenderUVToDisplayUV(Vector3 inputUV);

        Vector2
        RenderUVToDisplayUV(Vector2 inputUV);

        Vector2
        SolveDisplayUVToRenderUV(Vector2 inputUV,
                                 Vector2 initailGuess,
                                 int iterations);

        Vector2
        DisplayUVToRenderUVPreviousSeed(Vector2 inputUV);

        void
        RegenerateMesh();

        void
        UpdateEyePosition(const Vector3 pos)
        {
                eyePosition.x = pos.x;
                eyePosition.y = pos.y;
                eyePosition.z = pos.z;
        }

        const Vector4
        GetCameraProjection()
        {
                return cameraProjection;
        }

        void
        setiters(int init, int opt)
        {
                m_iniSolverIters = init;
                m_optSolverIters = opt;
        }

        void
        UpdateClipToWorld(Matrix4x4 eyeRotationMatrix)
        {
                Matrix4x4 eyeToWorld =
                    Matrix4x4::Translate(eyePosition) * eyeRotationMatrix;
                eyeToWorld.m02 *= -1;
                eyeToWorld.m12 *= -1;
                eyeToWorld.m22 *= -1;
                clipToWorld =
                    eyeToWorld * cameraProjection.ComposeProjection().Inverse();
        }

        Vector3 eyePosition;

        inline void
        ViewportPointToRayDirection(Vector2 UV,
                                    Vector3 cameraPosition,
                                    Matrix4x4 clipToWorld,
                                    Vector3 &out)
        {
                Vector3 tmp;
                tmp.x = UV.x - 0.5f;
                tmp.y = UV.y - 0.5f;
                tmp.z = 0.f;
                Vector3 dir =
                    clipToWorld.MultiplyPoint(tmp * 2.f) - cameraPosition;

                float mag = dir.Magnitude();
                out = dir / mag;
                return;
        }

private:
        float ellipseMinorAxis;
        float ellipseMajorAxis;
        Vector3 screenForward;
        Vector3 screenPosition;

        Vector4 cameraProjection;
        Matrix4x4 worldToSphereSpace;
        Matrix4x4 sphereToWorldSpace;
        Matrix4x4 worldToScreenSpace;
        Matrix4x4 clipToWorld;

        int m_iniSolverIters;
        int m_optSolverIters;

        std::map<float, std::map<float, Vector2> > m_requestedUVs;
};

// supporting functions
inline Vector3
Project(Vector3 v1, Vector3 v2)
{
        Vector3 v2Norm = (v2 / v2.Magnitude());
        return v2Norm * Vector3::Dot(v1, v2Norm);
}

inline float
intersectLineSphere(Vector3 Origin,
                    Vector3 Direction,
                    Vector3 spherePos,
                    float SphereRadiusSqrd,
                    bool frontSide = true)
{
        Vector3 L = spherePos - Origin;
        Vector3 offsetFromSphereCenterToRay = Project(L, Direction) - L;
        return (offsetFromSphereCenterToRay.sqrMagnitude() <= SphereRadiusSqrd)
                   ? Vector3::Dot(L, Direction) -
                         (sqrt(SphereRadiusSqrd -
                               offsetFromSphereCenterToRay.sqrMagnitude()) *
                          (frontSide ? 1.f : -1.f))
                   : -1.f;
}

inline float
intersectPlane(Vector3 n, Vector3 p0, Vector3 l0, Vector3 l)
{

        float denom = Vector3::Dot((Vector3::Zero() - n), l);
        if (denom > 1.4e-45f) {
                Vector3 p0l0 = p0 - l0;
                float t = Vector3::Dot(p0l0, (Vector3::Zero() - n)) / denom;
                return t;
        }
        return -1.f;
}