Vector4D.h

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/* Copyright (C) 2022 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. 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.
 *
 * 0 A.D. 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 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 * Provides an interface for a vector in R4 and allows vector and
 * scalar operations on it
 */

#ifndef INCLUDED_VECTOR4D
#define INCLUDED_VECTOR4D

#include "ps/containers/Span.h"

#include <math.h>

class CVector4D
{
public:
    CVector4D() : X(0.0f), Y(0.0f), Z(0.0f), W(0.0f) { }

    CVector4D(float x, float y, float z, float w) : X(x), Y(y), Z(z), W(w) { }

    bool operator==(const CVector4D& t) const
    {
        return (X == t.X && Y == t.Y && Z == t.Z && W == t.W);
    }

    bool operator!=(const CVector4D& t) const
    {
        return !(*this == t);
    }

    CVector4D operator-() const
    {
        return CVector4D(-X, -Y, -Z, -W);
    }

    CVector4D operator+(const CVector4D& t) const
    {
        return CVector4D(X+t.X, Y+t.Y, Z+t.Z, W+t.W);
    }

    CVector4D operator-(const CVector4D& t) const
    {
        return CVector4D(X-t.X, Y-t.Y, Z-t.Z, W-t.W);
    }

    CVector4D operator*(const CVector4D& t) const
    {
        return CVector4D(X*t.X, Y*t.Y, Z*t.Z, W*t.W);
    }

    CVector4D operator*(float f) const
    {
        return CVector4D(X*f, Y*f, Z*f, W*f);
    }

    CVector4D operator/(float f) const
    {
        float inv_f = 1.0f / f;
        return CVector4D(X*inv_f, Y*inv_f, Z*inv_f, W*inv_f);
    }

    CVector4D& operator+=(const CVector4D& t)
    {
        X += t.X;
        Y += t.Y;
        Z += t.Z;
        W += t.W;
        return *this;
    }

    CVector4D& operator-=(const CVector4D& t)
    {
        X -= t.X;
        Y -= t.Y;
        Z -= t.Z;
        W -= t.W;
        return *this;
    }

    CVector4D& operator*=(const CVector4D& t)
    {
        X *= t.X;
        Y *= t.Y;
        Z *= t.Z;
        W *= t.W;
        return *this;
    }

    CVector4D& operator*=(float f)
    {
        X *= f;
        Y *= f;
        Z *= f;
        W *= f;
        return *this;
    }

    CVector4D& operator/=(float f)
    {
        float inv_f = 1.0f / f;
        X *= inv_f;
        Y *= inv_f;
        Z *= inv_f;
        W *= inv_f;
        return *this;
    }

    float Dot(const CVector4D& a) const
    {
        return X*a.X + Y*a.Y + Z*a.Z + W*a.W;
    }

    // Returns 4 element array of floats, e.g. for vec4 uniforms.
    PS::span<const float> AsFloatArray() const
    {
        // Additional check to prevent a weird compiler has a different
        // alignement for an array and a class members.
        static_assert(
            sizeof(CVector4D) == sizeof(float) * 4u &&
            offsetof(CVector4D, X) == 0 &&
            offsetof(CVector4D, W) == sizeof(float) * 3u,
            "CVector4D should be properly layouted to use AsFloatArray");
        return PS::span<const float>(&X, 4);
    }

    float X, Y, Z, W;
};

#endif // INCLUDED_VECTOR4D