crown-engine/engine/core/math/aabb.h

/*
Copyright (c) 2013 Daniele Bartolini, Michele Rossi
Copyright (c) 2012 Daniele Bartolini, Simone Boscaratto

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
*/

#pragma once

#include "assert.h"
#include "math_types.h"
#include "matrix4x4.h"
#include "sphere.h"
#include "types.h"
#include "vector3.h"

namespace crown
{

/// Functions to manipulate AABB.
///
/// @ingroup Math
namespace aabb
{
	void reset(AABB& b);

	/// Returns the center of the box @a b.
	Vector3 center(const AABB& b);

	/// Returns the radius of the box @a b.
	float radius(const AABB& b);

	/// Returns the volume of the box @a b.
	float volume(const AABB& b);

	/// Adds @a num @a points to the box @a b, expanding its bounds if necessary.
	void add_points(AABB& b, uint32_t num, const Vector3* points);

	/// Adds @a num @a boxes to the box @a b, expanding its bounds if necessary.
	void add_boxes(AABB& b, uint32_t num, const AABB* boxes);

	/// Returns whether point @a p is contained in the box @a b.
	bool contains_point(const AABB& b, const Vector3& p);

	/// Returns the @a index -th vertex of the box.
	Vector3 vertex(const AABB& b, uint32_t index);

	/// Returns the box enclosing @a b transformed by @a m.
	AABB transformed(const AABB& b, const Matrix4x4& m);

	/// Returns the eight vertices of the box @a b.
	void to_vertices(const AABB& b, Vector3 v[8]);

	/// Returns the sphere enclosing the box @a b.
	Sphere to_sphere(const AABB& b);
}

namespace aabb
{
	//-----------------------------------------------------------------------------
	inline void reset(AABB& b)
	{
		b.min = vector3::ZERO;
		b.max = vector3::ZERO;
	}

	//-----------------------------------------------------------------------------
	inline Vector3 center(const AABB& b)
	{
		return (b.min + b.max) * 0.5;
	}

	//-----------------------------------------------------------------------------
	inline float radius(const AABB& b)
	{
		return vector3::length(b.max - (b.min + b.max) * 0.5);
	}
	//-----------------------------------------------------------------------------
	inline float volume(const AABB& b)
	{
		return (b.max.x - b.min.x) * (b.max.y - b.min.y) * (b.max.z - b.min.z);
	}

	//-----------------------------------------------------------------------------
	inline void add_points(AABB& b, uint32_t num, const Vector3* points)
	{
		for (uint32_t i = 0; i < num; i++)
		{
			const Vector3& p = points[i];

			if (p.x < b.min.x) b.min.x = p.x;
			if (p.y < b.min.y) b.min.y = p.y;
			if (p.z < b.min.z) b.min.z = p.z;
			if (p.x > b.max.x) b.max.x = p.x;
			if (p.y > b.max.y) b.max.y = p.y;
			if (p.z > b.max.z) b.max.z = p.z;
		}
	}

	//-----------------------------------------------------------------------------
	inline void add_boxes(AABB& b, uint32_t num, const AABB* boxes)
	{
		for (uint32_t i = 0; i < num; i++)
		{
			const AABB& box = boxes[i];

			if (box.min.x < b.min.x) b.min.x = box.min.x;
			if (box.min.y < b.min.y) b.min.y = box.min.y;
			if (box.min.z < b.min.z) b.min.z = box.min.z;
			if (box.max.x > b.max.x) b.max.x = box.max.x;
			if (box.max.y > b.max.y) b.max.y = box.max.y;
			if (box.max.z > b.max.z) b.max.z = box.max.z;
		}
	}

	//-----------------------------------------------------------------------------
	inline bool contains_point(const AABB& b, const Vector3& p)
	{
		return (p.x > b.min.x &&
				p.y > b.min.y &&
				p.z > b.min.z &&
				p.x < b.max.x &&
				p.y < b.max.y &&
				p.z < b.max.z);
	}

	//-----------------------------------------------------------------------------
	inline Vector3 vertex(const AABB& b, uint32_t index)
	{
		CE_ASSERT(index < 8, "Index must be < 8");

		switch (index)
		{
			case 0: return Vector3(b.min.x, b.min.y, b.min.z);
			case 1: return Vector3(b.max.x, b.min.y, b.min.z);
			case 2: return Vector3(b.max.x, b.min.y, b.max.z);
			case 3: return Vector3(b.min.x, b.min.y, b.max.z);
			case 4: return Vector3(b.min.x, b.max.y, b.min.z);
			case 5: return Vector3(b.max.x, b.max.y, b.min.z);
			case 6: return Vector3(b.max.x, b.max.y, b.max.z);
			case 7: return Vector3(b.min.x, b.max.y, b.max.z);
		}
	}

	//-----------------------------------------------------------------------------
	inline AABB transformed(const AABB& b, const Matrix4x4& m)
	{
		Vector3 vertices[8];
		to_vertices(b, vertices);

		vertices[0] = m * vertices[0];
		vertices[1] = m * vertices[1];
		vertices[2] = m * vertices[2];
		vertices[3] = m * vertices[3];
		vertices[4] = m * vertices[4];
		vertices[5] = m * vertices[5];
		vertices[6] = m * vertices[6];
		vertices[7] = m * vertices[7];

		AABB res;
		reset(res);
		add_points(res, 8, vertices);
		return res;
	}

	//-----------------------------------------------------------------------------
	inline void to_vertices(const AABB& b, Vector3 v[8])
	{
		// 7 ---- 6
		// |      |
		// |      |  <--- Top face
		// 4 ---- 5
		//
		// 3 ---- 2
		// |      |
		// |      |  <--- Bottom face
		// 0 ---- 1
		v[0].x = b.min.x;
		v[0].y = b.min.y;
		v[0].z = b.max.z;

		v[1].x = b.max.x;
		v[1].y = b.min.y;
		v[1].z = b.max.z;

		v[2].x = b.max.x;
		v[2].y = b.min.y;
		v[2].z = b.min.z;

		v[3].x = b.min.x;
		v[3].y = b.min.y;
		v[3].z = b.min.z;

		v[4].x = b.min.x;
		v[4].y = b.max.y;
		v[4].z = b.max.z;

		v[5].x = b.max.x;
		v[5].y = b.max.y;
		v[5].z = b.max.z;

		v[6].x = b.max.x;
		v[6].y = b.max.y;
		v[6].z = b.min.z;

		v[7].x = b.min.x;
		v[7].y = b.max.y;
		v[7].z = b.min.z;
	}

	//-----------------------------------------------------------------------------
	inline Sphere to_sphere(const AABB& b)
	{
		return Sphere(center(b), radius(b));
	}
} // namespace aabb

//-----------------------------------------------------------------------------
inline AABB::AABB()
{
	// Do not initialize
}

//-----------------------------------------------------------------------------
inline AABB::AABB(const Vector3& min, const Vector3& max)
	: min(min), max(max)
{
}

} // namespace crown