geometry.h

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/*
    pbrt source code Copyright(c) 1998-2010 Matt Pharr and Greg Humphreys.

    This file is part of pbrt.

    pbrt 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.  Note that the text contents of
    the book "Physically Based Rendering" are *not* licensed under the
    GNU GPL.

    pbrt 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, see <http://www.gnu.org/licenses/>.

 */

#if defined(_MSC_VER)
#pragma once
#endif

#ifndef PBRT_CORE_GEOMETRY_H
#define PBRT_CORE_GEOMETRY_H

// core/geometry.h*
#include "pbrt.h"

// Geometry Declarations
class Vector {
public:
    // Vector Public Methods
    Vector() { x = y = z = 0.f; }
    Vector(float xx, float yy, float zz)
        : x(xx), y(yy), z(zz) {
        Assert(!HasNaNs());
    }
    bool HasNaNs() const { return isnan(x) || isnan(y) || isnan(z); }
    explicit Vector(const Point &p);
#ifndef NDEBUG
    // The default versions of these are fine for release builds; for debug
    // we define them so that we can add the Assert checks.
    Vector(const Vector &v) {
        Assert(!v.HasNaNs());
        x = v.x; y = v.y; z = v.z;
    }
    
    Vector &operator=(const Vector &v) {
        Assert(!v.HasNaNs());
        x = v.x; y = v.y; z = v.z;
        return *this;
    }
#endif // !NDEBUG
    Vector operator+(const Vector &v) const {
        Assert(!v.HasNaNs());
        return Vector(x + v.x, y + v.y, z + v.z);
    }
    
    Vector& operator+=(const Vector &v) {
        Assert(!v.HasNaNs());
        x += v.x; y += v.y; z += v.z;
        return *this;
    }
    Vector operator-(const Vector &v) const {
        Assert(!v.HasNaNs());
        return Vector(x - v.x, y - v.y, z - v.z);
    }
    
    Vector& operator-=(const Vector &v) {
        Assert(!v.HasNaNs());
        x -= v.x; y -= v.y; z -= v.z;
        return *this;
    }
    bool operator==(const Vector &v) const {
        return x == v.x && y == v.y && z == v.z;
    }
    Vector operator*(float f) const { return Vector(f*x, f*y, f*z); }
    
    Vector &operator*=(float f) {
        Assert(!isnan(f));
        x *= f; y *= f; z *= f;
        return *this;
    }
    Vector operator/(float f) const {
        Assert(f != 0);
        float inv = 1.f / f;
        return Vector(x * inv, y * inv, z * inv);
    }
    
    Vector &operator/=(float f) {
        Assert(f != 0);
        float inv = 1.f / f;
        x *= inv; y *= inv; z *= inv;
        return *this;
    }
    Vector operator-() const { return Vector(-x, -y, -z); }
    float operator[](int i) const {
        Assert(i >= 0 && i <= 2);
        return (&x)[i];
    }
    
    float &operator[](int i) {
        Assert(i >= 0 && i <= 2);
        return (&x)[i];
    }
    float LengthSquared() const { return x*x + y*y + z*z; }
    float Length() const { return sqrtf(LengthSquared()); }
    explicit Vector(const Normal &n);

    // Vector Public Data
    float x, y, z;
};


class Point {
public:
    // Point Public Methods
    Point() { x = y = z = 0.f; }
    Point(float xx, float yy, float zz)
        : x(xx), y(yy), z(zz) {
        Assert(!HasNaNs());
    }
#ifndef NDEBUG
    Point(const Point &p) {
        Assert(!p.HasNaNs());
        x = p.x; y = p.y; z = p.z;
    }
    
    Point &operator=(const Point &p) {
        Assert(!p.HasNaNs());
        x = p.x; y = p.y; z = p.z;
        return *this;
    }
#endif // !NDEBUG
    Point operator+(const Vector &v) const {
        Assert(!v.HasNaNs());
        return Point(x + v.x, y + v.y, z + v.z);
    }
    
    Point &operator+=(const Vector &v) {
        Assert(!v.HasNaNs());
        x += v.x; y += v.y; z += v.z;
        return *this;
    }
    Vector operator-(const Point &p) const {
        Assert(!p.HasNaNs());
        return Vector(x - p.x, y - p.y, z - p.z);
    }
    
    Point operator-(const Vector &v) const {
        Assert(!v.HasNaNs());
        return Point(x - v.x, y - v.y, z - v.z);
    }
    
    Point &operator-=(const Vector &v) {
        Assert(!v.HasNaNs());
        x -= v.x; y -= v.y; z -= v.z;
        return *this;
    }
    Point &operator+=(const Point &p) {
        Assert(!p.HasNaNs());
        x += p.x; y += p.y; z += p.z;
        return *this;
    }
    Point operator+(const Point &p) const {
        Assert(!p.HasNaNs());
        return Point(x + p.x, y + p.y, z + p.z);
    }
    Point operator* (float f) const {
        return Point(f*x, f*y, f*z);
    }
    Point &operator*=(float f) {
        x *= f; y *= f; z *= f;
        return *this;
    }
    Point operator/ (float f) const {
        float inv = 1.f/f;
        return Point(inv*x, inv*y, inv*z);
    }
    Point &operator/=(float f) {
        float inv = 1.f/f;
        x *= inv; y *= inv; z *= inv;
        return *this;
    }
    float operator[](int i) const {
        Assert(i >= 0 && i <= 2);
        return (&x)[i];
    }
    
    float &operator[](int i) {
        Assert(i >= 0 && i <= 2);
        return (&x)[i];
    }
    bool HasNaNs() const {
        return isnan(x) || isnan(y) || isnan(z);
    }

    // Point Public Data
    float x, y, z;
};


class Normal {
public:
    // Normal Public Methods
    Normal() { x = y = z = 0.f; }
    Normal(float xx, float yy, float zz)
        : x(xx), y(yy), z(zz) {
        Assert(!HasNaNs());
    }
    Normal operator-() const {
        return Normal(-x, -y, -z);
    }
    Normal operator+ (const Normal &n) const {
        Assert(!n.HasNaNs());
        return Normal(x + n.x, y + n.y, z + n.z);
    }
    
    Normal& operator+=(const Normal &n) {
        Assert(!n.HasNaNs());
        x += n.x; y += n.y; z += n.z;
        return *this;
    }
    Normal operator- (const Normal &n) const {
        Assert(!n.HasNaNs());
        return Normal(x - n.x, y - n.y, z - n.z);
    }
    
    Normal& operator-=(const Normal &n) {
        Assert(!n.HasNaNs());
        x -= n.x; y -= n.y; z -= n.z;
        return *this;
    }
    bool HasNaNs() const {
        return isnan(x) || isnan(y) || isnan(z);
    }
    Normal operator*(float f) const {
        return Normal(f*x, f*y, f*z);
    }
    
    Normal &operator*=(float f) {
        x *= f; y *= f; z *= f;
        return *this;
    }
    Normal operator/(float f) const {
        Assert(f != 0);
        float inv = 1.f/f;
        return Normal(x * inv, y * inv, z * inv);
    }
    
    Normal &operator/=(float f) {
        Assert(f != 0);
        float inv = 1.f/f;
        x *= inv; y *= inv; z *= inv;
        return *this;
    }
    float LengthSquared() const { return x*x + y*y + z*z; }
    float Length() const        { return sqrtf(LengthSquared()); }
    
#ifndef NDEBUG
    Normal(const Normal &n) {
        Assert(!n.HasNaNs());
        x = n.x; y = n.y; z = n.z;
    }
    
    Normal &operator=(const Normal &n) {
        Assert(!n.HasNaNs());
        x = n.x; y = n.y; z = n.z;
        return *this;
    }
#endif // !NDEBUG
    explicit Normal(const Vector &v)
      : x(v.x), y(v.y), z(v.z) {
        Assert(!v.HasNaNs());
    }
    float operator[](int i) const {
        Assert(i >= 0 && i <= 2);
        return (&x)[i];
    }
    
    float &operator[](int i) {
        Assert(i >= 0 && i <= 2);
        return (&x)[i];
    }

    // Normal Public Data
    float x, y, z;
};


class Ray {
public:
    // Ray Public Methods
    Ray() : mint(0.f), maxt(INFINITY), time(0.f), depth(0) { }
    Ray(const Point &origin, const Vector &direction,
        float start, float end = INFINITY, float t = 0.f, int d = 0)
        : o(origin), d(direction), mint(start), maxt(end), time(t), depth(d) { }
    Ray(const Point &origin, const Vector &direction, const Ray &parent,
        float start, float end = INFINITY)
        : o(origin), d(direction), mint(start), maxt(end),
          time(parent.time), depth(parent.depth+1) { }
    Point operator()(float t) const { return o + d * t; }
    bool HasNaNs() const {
        return (o.HasNaNs() || d.HasNaNs() ||
                isnan(mint) || isnan(maxt));
    }

    // Ray Public Data
    Point o;
    Vector d;
    mutable float mint, maxt;
    float time;
    int depth;
};


class RayDifferential : public Ray {
public:
    // RayDifferential Public Methods
    RayDifferential() { hasDifferentials = false; }
    RayDifferential(const Point &org, const Vector &dir, float start,
        float end = INFINITY, float t = 0.f, int d = 0)
            : Ray(org, dir, start, end, t, d) {
        hasDifferentials = false;
    }
    RayDifferential(const Point &org, const Vector &dir, const Ray &parent,
        float start, float end = INFINITY)
            : Ray(org, dir, start, end, parent.time, parent.depth+1) {
        hasDifferentials = false;
    }
    explicit RayDifferential(const Ray &ray) : Ray(ray) {
        hasDifferentials = false;
    }
    bool HasNaNs() const {
        return Ray::HasNaNs() ||
           (hasDifferentials && (rxOrigin.HasNaNs() || ryOrigin.HasNaNs() ||
                                 rxDirection.HasNaNs() || ryDirection.HasNaNs()));
    }
    void ScaleDifferentials(float s) {
        rxOrigin = o + (rxOrigin - o) * s;
        ryOrigin = o + (ryOrigin - o) * s;
        rxDirection = d + (rxDirection - d) * s;
        ryDirection = d + (ryDirection - d) * s;
    }

    // RayDifferential Public Data
    bool hasDifferentials;
    Point rxOrigin, ryOrigin;
    Vector rxDirection, ryDirection;
};


class BBox {
public:
    // BBox Public Methods
    BBox() {
        pMin = Point( INFINITY,  INFINITY,  INFINITY);
        pMax = Point(-INFINITY, -INFINITY, -INFINITY);
    }
    BBox(const Point &p) : pMin(p), pMax(p) { }
    BBox(const Point &p1, const Point &p2) {
        pMin = Point(min(p1.x, p2.x), min(p1.y, p2.y), min(p1.z, p2.z));
        pMax = Point(max(p1.x, p2.x), max(p1.y, p2.y), max(p1.z, p2.z));
    }
    friend BBox Union(const BBox &b, const Point &p);
    friend BBox Union(const BBox &b, const BBox &b2);
    bool Overlaps(const BBox &b) const {
        bool x = (pMax.x >= b.pMin.x) && (pMin.x <= b.pMax.x);
        bool y = (pMax.y >= b.pMin.y) && (pMin.y <= b.pMax.y);
        bool z = (pMax.z >= b.pMin.z) && (pMin.z <= b.pMax.z);
        return (x && y && z);
    }
    bool Inside(const Point &pt) const {
        return (pt.x >= pMin.x && pt.x <= pMax.x &&
                pt.y >= pMin.y && pt.y <= pMax.y &&
                pt.z >= pMin.z && pt.z <= pMax.z);
    }
    void Expand(float delta) {
        pMin -= Vector(delta, delta, delta);
        pMax += Vector(delta, delta, delta);
    }
    float SurfaceArea() const {
        Vector d = pMax - pMin;
        return 2.f * (d.x * d.y + d.x * d.z + d.y * d.z);
    }
    float Volume() const {
        Vector d = pMax - pMin;
        return d.x * d.y * d.z;
    }
    int MaximumExtent() const {
        Vector diag = pMax - pMin;
        if (diag.x > diag.y && diag.x > diag.z)
            return 0;
        else if (diag.y > diag.z)
            return 1;
        else
            return 2;
    }
    const Point &operator[](int i) const;
    Point &operator[](int i);
    Point Lerp(float tx, float ty, float tz) const {
        return Point(::Lerp(tx, pMin.x, pMax.x), ::Lerp(ty, pMin.y, pMax.y),
                     ::Lerp(tz, pMin.z, pMax.z));
    }
    Vector Offset(const Point &p) const {
        return Vector((p.x - pMin.x) / (pMax.x - pMin.x),
                      (p.y - pMin.y) / (pMax.y - pMin.y),
                      (p.z - pMin.z) / (pMax.z - pMin.z));
    }
    void BoundingSphere(Point *c, float *rad) const;
    bool IntersectP(const Ray &ray, float *hitt0 = NULL, float *hitt1 = NULL) const;

    // BBox Public Data
    Point pMin, pMax;
};



// Geometry Inline Functions
inline Vector::Vector(const Point &p)
    : x(p.x), y(p.y), z(p.z) {
    Assert(!HasNaNs());
}


inline Vector operator*(float f, const Vector &v) { return v*f; }
inline float Dot(const Vector &v1, const Vector &v2) {
    Assert(!v1.HasNaNs() && !v2.HasNaNs());
    return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
}


inline float AbsDot(const Vector &v1, const Vector &v2) {
    Assert(!v1.HasNaNs() && !v2.HasNaNs());
    return fabsf(Dot(v1, v2));
}


inline Vector Cross(const Vector &v1, const Vector &v2) {
    Assert(!v1.HasNaNs() && !v2.HasNaNs());
    double v1x = v1.x, v1y = v1.y, v1z = v1.z;
    double v2x = v2.x, v2y = v2.y, v2z = v2.z;
    return Vector((v1y * v2z) - (v1z * v2y),
                  (v1z * v2x) - (v1x * v2z),
                  (v1x * v2y) - (v1y * v2x));
}


inline Vector Cross(const Vector &v1, const Normal &v2) {
    Assert(!v1.HasNaNs() && !v2.HasNaNs());
    double v1x = v1.x, v1y = v1.y, v1z = v1.z;
    double v2x = v2.x, v2y = v2.y, v2z = v2.z;
    return Vector((v1y * v2z) - (v1z * v2y),
                  (v1z * v2x) - (v1x * v2z),
                  (v1x * v2y) - (v1y * v2x));
}


inline Vector Cross(const Normal &v1, const Vector &v2) {
    Assert(!v1.HasNaNs() && !v2.HasNaNs());
    double v1x = v1.x, v1y = v1.y, v1z = v1.z;
    double v2x = v2.x, v2y = v2.y, v2z = v2.z;
    return Vector((v1y * v2z) - (v1z * v2y),
                  (v1z * v2x) - (v1x * v2z),
                  (v1x * v2y) - (v1y * v2x));
}


inline Vector Normalize(const Vector &v) { return v / v.Length(); }
inline void CoordinateSystem(const Vector &v1, Vector *v2, Vector *v3) {
    if (fabsf(v1.x) > fabsf(v1.y)) {
        float invLen = 1.f / sqrtf(v1.x*v1.x + v1.z*v1.z);
        *v2 = Vector(-v1.z * invLen, 0.f, v1.x * invLen);
    }
    else {
        float invLen = 1.f / sqrtf(v1.y*v1.y + v1.z*v1.z);
        *v2 = Vector(0.f, v1.z * invLen, -v1.y * invLen);
    }
    *v3 = Cross(v1, *v2);
}


inline float Distance(const Point &p1, const Point &p2) {
    return (p1 - p2).Length();
}


inline float DistanceSquared(const Point &p1, const Point &p2) {
    return (p1 - p2).LengthSquared();
}


inline Point operator*(float f, const Point &p) {
    Assert(!p.HasNaNs());
    return p*f;
}


inline Normal operator*(float f, const Normal &n) {
    return Normal(f*n.x, f*n.y, f*n.z);
}


inline Normal Normalize(const Normal &n) {
    return n / n.Length();
}


inline Vector::Vector(const Normal &n)
  : x(n.x), y(n.y), z(n.z) {
    Assert(!n.HasNaNs());
}


inline float Dot(const Normal &n1, const Vector &v2) {
    Assert(!n1.HasNaNs() && !v2.HasNaNs());
    return n1.x * v2.x + n1.y * v2.y + n1.z * v2.z;
}


inline float Dot(const Vector &v1, const Normal &n2) {
    Assert(!v1.HasNaNs() && !n2.HasNaNs());
    return v1.x * n2.x + v1.y * n2.y + v1.z * n2.z;
}


inline float Dot(const Normal &n1, const Normal &n2) {
    Assert(!n1.HasNaNs() && !n2.HasNaNs());
    return n1.x * n2.x + n1.y * n2.y + n1.z * n2.z;
}


inline float AbsDot(const Normal &n1, const Vector &v2) {
    Assert(!n1.HasNaNs() && !v2.HasNaNs());
    return fabsf(n1.x * v2.x + n1.y * v2.y + n1.z * v2.z);
}


inline float AbsDot(const Vector &v1, const Normal &n2) {
    Assert(!v1.HasNaNs() && !n2.HasNaNs());
    return fabsf(v1.x * n2.x + v1.y * n2.y + v1.z * n2.z);
}


inline float AbsDot(const Normal &n1, const Normal &n2) {
    Assert(!n1.HasNaNs() && !n2.HasNaNs());
    return fabsf(n1.x * n2.x + n1.y * n2.y + n1.z * n2.z);
}


inline Normal Faceforward(const Normal &n, const Vector &v) {
    return (Dot(n, v) < 0.f) ? -n : n;
}


inline Normal Faceforward(const Normal &n, const Normal &n2) {
    return (Dot(n, n2) < 0.f) ? -n : n;
}



inline Vector Faceforward(const Vector &v, const Vector &v2) {
    return (Dot(v, v2) < 0.f) ? -v : v;
}



inline Vector Faceforward(const Vector &v, const Normal &n2) {
    return (Dot(v, n2) < 0.f) ? -v : v;
}


inline const Point &BBox::operator[](int i) const {
    Assert(i == 0 || i == 1);
    return (&pMin)[i];
}



inline Point &BBox::operator[](int i) {
    Assert(i == 0 || i == 1);
    return (&pMin)[i];
}


inline Vector SphericalDirection(float sintheta,
                                 float costheta, float phi) {
    return Vector(sintheta * cosf(phi),
                  sintheta * sinf(phi),
                  costheta);
}


inline Vector SphericalDirection(float sintheta, float costheta,
                                 float phi, const Vector &x,
                                 const Vector &y, const Vector &z) {
    return sintheta * cosf(phi) * x +
           sintheta * sinf(phi) * y + costheta * z;
}


inline float SphericalTheta(const Vector &v) {
    return acosf(Clamp(v.z, -1.f, 1.f));
}


inline float SphericalPhi(const Vector &v) {
    float p = atan2f(v.y, v.x);
    return (p < 0.f) ? p + 2.f*M_PI : p;
}



#endif // PBRT_CORE_GEOMETRY_H

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