BoxHelper.cpp

/*
	This file is part of the Geometry library.
	Copyright (C) 2007-2012 Benjamin Eikel <benjamin@eikel.org>
	Copyright (C) 2007-2012 Claudius Jähn <claudius@uni-paderborn.de>
	Copyright (C) 2007-2012 Ralf Petring <ralf@petring.net>

	This library is subject to the terms of the Mozilla Public License, v. 2.0.
	You should have received a copy of the MPL along with this library; see the
	file LICENSE. If not, you can obtain one at http://mozilla.org/MPL/2.0/.
*/
#include "BoxHelper.h"
#include "Box.h"
#include "Matrix4x4.h"
#include <array>
#include <vector>

namespace Geometry {
namespace Helper {

//
//	^Y
//	 |
//	 |
//	 |
//	 o---> X
//	 /
//	Z / .---------.
// / Top: /|
// / 4 / |--Back: 2
// .---------. |
// Left: | | ----Right: 3
// 0---| Front: | |
// | 5 | /
// | |/--Bottom: 1
// '---------'
// 2---------3
// /| /|
// / | / |
// 6---------7 |
// | | | |
// | 0------|--1
// | / | /
// |/ |/
// 4---------5
//
//	corner_t::xyz = 0,
//	corner_t::Xyz = 1,
//	corner_t::xYz = 2,
//	corner_t::XYz = 3,
//	corner_t::xyZ = 4,
//	corner_t::XyZ = 5,
//	corner_t::xYZ = 6,
//	corner_t::XYZ = 7
const corner_t * getCornerIndices(const side_t side) {
	static const corner_t corners[6][4] = {
			{corner_t::xyz, corner_t::xyZ, corner_t::xYZ, corner_t::xYz}, // left
			{corner_t::XyZ, corner_t::xyZ, corner_t::xyz, corner_t::Xyz}, // bottom
			{corner_t::Xyz, corner_t::xyz, corner_t::xYz, corner_t::XYz}, // back
			{corner_t::XyZ, corner_t::Xyz, corner_t::XYz, corner_t::XYZ}, // right
			{corner_t::XYz, corner_t::xYz, corner_t::xYZ, corner_t::XYZ}, // top
			{corner_t::xyZ, corner_t::XyZ, corner_t::XYZ, corner_t::xYZ} // front
	};
	return corners[static_cast<std::size_t>(side)];
}

const Vec3f & getNormal(const side_t side) {
	static const Vec3f normals[6] = {
			Vec3f(-1, 0, 0), // left
			Vec3f(0, -1, 0), // bottom
			Vec3f(0, 0, -1), // back
			Vec3f(1, 0, 0), // right
			Vec3f(0, 1, 0), // top
			Vec3f(0, 0, 1) // front
	};
	return normals[static_cast<std::size_t>(side)];
}

std::vector<Box_f> splitUpBox(const Box_f & box, unsigned int partsX, unsigned int partsY, unsigned int partsZ) {
	if (box.isInvalid()) {
		std::cerr << __FILE__ << ":" << __LINE__ << ":" << std::endl
				 << "\t you are splitting invalid boxes" << std::endl;
	}

	std::vector<Box_f> result;
	const unsigned int num = partsX * partsY * partsZ;
	if (num == 0) {
		return result;
	} else if (num == 1) {
		result.emplace_back(box);
		return result;
	}
	result.reserve(num);

	float lastZ = box.getMinZ();
	float newMaxZ = 0.0f;
	for (unsigned int cz = 1; cz <= partsZ; ++cz) {
		float lastY = box.getMinY();
		float newMaxY = 0.0f;
		for (unsigned int cy = 1; cy <= partsY; ++cy) {
			float lastX = box.getMinX();
			float newMaxX;
			for (unsigned int cx = 1; cx <= partsX; ++cx) {
				// Interpolate between minimum and maximum values.
				if (cx == partsX) {
					newMaxX = box.getMaxX();
				} else {
					const float uX = static_cast<float>(partsX - cx) / static_cast<float>(partsX);
					const float vX = static_cast<float>(cx) / static_cast<float>(partsX);
					newMaxX = uX * box.getMinX() + vX * box.getMaxX();
				}
				if (cy == partsY) {
					newMaxY = box.getMaxY();
				} else {
					const float uY = static_cast<float>(partsY - cy) / static_cast<float>(partsY);
					const float vY = static_cast<float>(cy) / static_cast<float>(partsY);
					newMaxY = uY * box.getMinY() + vY * box.getMaxY();
				}
				if (cz == partsZ) {
					newMaxZ = box.getMaxZ();
				} else {
					const float uZ = static_cast<float>(partsZ - cz) / static_cast<float>(partsZ);
					const float vZ = static_cast<float>(cz) / static_cast<float>(partsZ);
					newMaxZ = uZ * box.getMinZ() + vZ * box.getMaxZ();
				}
				result.emplace_back(lastX, newMaxX, lastY, newMaxY, lastZ, newMaxZ);
				lastX = newMaxX;
			}
			lastY = newMaxY;
		}
		lastZ = newMaxZ;
	}
	return result;
}

std::vector<Box_f> splitBoxCubeLike(const Box_f & box) {
	static const float isq2 = 1.0f / std::sqrt(2.0f);

	float x = box.getExtentX(), y = box.getExtentY(), z = box.getExtentZ();

	if (x >= y) {
		if (y >= z) { // x >= y >= z
			if (x * isq2 > y)
				return splitUpBox(box, 2, 1, 1);
			else if (x * isq2 > z)
				return splitUpBox(box, 2, 2, 1);
			else
				return splitUpBox(box, 2, 2, 2);
		} else if (x >= z) { // x >= z >= y
			if (x * isq2 > z)
				return splitUpBox(box, 2, 1, 1);
			else if (x * isq2 > y)
				return splitUpBox(box, 2, 1, 2);
			else
				return splitUpBox(box, 2, 2, 2);
		} else { // z >= x >= y
			if (z * isq2 > x)
				return splitUpBox(box, 1, 1, 2);
			else if (z * isq2 > y)
				return splitUpBox(box, 2, 1, 2);
			else
				return splitUpBox(box, 2, 2, 2);
		}
	} else { // y >= x
		if (x >= z) { // y >= x >= z
			if (y * isq2 > x)
				return splitUpBox(box, 1, 2, 1);
			else if (y * isq2 > z)
				return splitUpBox(box, 2, 2, 1);
			else
				return splitUpBox(box, 2, 2, 2);
		} else if (y >= z) { // y >= z >= x
			if (y * isq2 > z)
				return splitUpBox(box, 1, 2, 1);
			else if (y * isq2 > x)
				return splitUpBox(box, 1, 2, 2);
			else
				return splitUpBox(box, 2, 2, 2);
		} else { // z >= y >= x
			if (z * isq2 > y)
				return splitUpBox(box, 1, 1, 2);
			else if (z * isq2 > x)
				return splitUpBox(box, 1, 2, 2);
			else
				return splitUpBox(box, 2, 2, 2);
		}
	}
}

Box_f getTransformedBox(const Box_f & box, const Matrix4x4f & matrix) {
	Box_f result;
	result.invalidate();
	result.include(matrix.transformPosition(box.getCorner(corner_t::xyz)));
	result.include(matrix.transformPosition(box.getCorner(corner_t::Xyz)));
	result.include(matrix.transformPosition(box.getCorner(corner_t::xYz)));
	result.include(matrix.transformPosition(box.getCorner(corner_t::XYz)));
	result.include(matrix.transformPosition(box.getCorner(corner_t::xyZ)));
	result.include(matrix.transformPosition(box.getCorner(corner_t::XyZ)));
	result.include(matrix.transformPosition(box.getCorner(corner_t::xYZ)));
	result.include(matrix.transformPosition(box.getCorner(corner_t::XYZ)));
	return result;
}
}
}