hydra/include/triangle3.h

//
//  KRTriangle.h
//  Kraken Engine / Hydra
//
//  Copyright 2024 Kearwood Gilbert. All rights reserved.
//
//  Redistribution and use in source and binary forms, with or without modification, are
//  permitted provided that the following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice, this list of
//  conditions and the following disclaimer.
//
//  2. 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.
//
//  THIS SOFTWARE IS PROVIDED BY KEARWOOD GILBERT ''AS IS'' AND ANY EXPRESS OR IMPLIED
//  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
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//  or implied, of Kearwood Gilbert.
//

#pragma once

#include "vector3.h"

namespace hydra {

class Triangle3
{
public:
  Vector3 vert[3];

  void init(const Triangle3& tri);
  void init(const Vector3& v1, const Vector3& v2, const Vector3& v3);
  static Triangle3 Create(const Triangle3& tri);
  static Triangle3 Create(const Vector3& v1, const Vector3& v2, const Vector3& v3);

  Vector3 calculateNormal() const;

  bool operator ==(const Triangle3& b) const;
  bool operator !=(const Triangle3& b) const;
  Vector3& operator[](unsigned int i);
  Vector3 operator[](unsigned int i) const;

  bool rayCast(const Vector3& start, const Vector3& dir, Vector3& hit_point) const;
  bool sphereCast(const Vector3& start, const Vector3& dir, float radius, Vector3& hit_point, float& hit_distance) const;

  bool containsPoint(const Vector3& p) const;
  Vector3 closestPointOnTriangle(const Vector3& p) const;
};
static_assert(std::is_pod<Triangle3>::value, "hydra::Triangle3 must be a POD type.");

} // namespace hydra

namespace std {
template<>
struct hash<hydra::Triangle3>
{
public:
  size_t operator()(const hydra::Triangle3& s) const
  {
    size_t h1 = hash<hydra::Vector3>()(s.vert[0]);
    size_t h2 = hash<hydra::Vector3>()(s.vert[1]);
    size_t h3 = hash<hydra::Vector3>()(s.vert[2]);
    return h1 ^ (h2 << 1) ^ (h3 << 2);
  }
};
} // namespace std