axmol/core/3d/AABB.cpp

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 Copyright (c) 2014-2016 Chukong Technologies Inc.
 Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

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#include "3d/AABB.h"

namespace ax
{

AABB::AABB()
{
    reset();
}

AABB::AABB(const Vec3& min, const Vec3& max)
{
    set(min, max);
}

Vec3 AABB::getCenter()
{
    Vec3 center;
    center.x = 0.5f * (_min.x + _max.x);
    center.y = 0.5f * (_min.y + _max.y);
    center.z = 0.5f * (_min.z + _max.z);

    return center;
}

void AABB::getCorners(Vec3* dst) const
{
    assert(dst);

    // Near face, specified counter-clockwise looking towards the origin from the positive z-axis.
    // Left-top-front.
    dst[0].set(_min.x, _max.y, _max.z);
    // Left-bottom-front.
    dst[1].set(_min.x, _min.y, _max.z);
    // Right-bottom-front.
    dst[2].set(_max.x, _min.y, _max.z);
    // Right-top-front.
    dst[3].set(_max.x, _max.y, _max.z);

    // Far face, specified counter-clockwise looking towards the origin from the negative z-axis.
    // Right-top-back.
    dst[4].set(_max.x, _max.y, _min.z);
    // Right-bottom-back.
    dst[5].set(_max.x, _min.y, _min.z);
    // Left-bottom-back.
    dst[6].set(_min.x, _min.y, _min.z);
    // Left-top-back.
    dst[7].set(_min.x, _max.y, _min.z);
}

bool AABB::intersects(const AABB& aabb) const
{
    return ((_min.x >= aabb._min.x && _min.x <= aabb._max.x) || (aabb._min.x >= _min.x && aabb._min.x <= _max.x)) &&
           ((_min.y >= aabb._min.y && _min.y <= aabb._max.y) || (aabb._min.y >= _min.y && aabb._min.y <= _max.y)) &&
           ((_min.z >= aabb._min.z && _min.z <= aabb._max.z) || (aabb._min.z >= _min.z && aabb._min.z <= _max.z));
}

bool AABB::containPoint(const Vec3& point) const
{
    if (point.x < _min.x)
        return false;
    if (point.y < _min.y)
        return false;
    if (point.z < _min.z)
        return false;
    if (point.x > _max.x)
        return false;
    if (point.y > _max.y)
        return false;
    if (point.z > _max.z)
        return false;
    return true;
}

void AABB::merge(const AABB& box)
{
    // Calculate the new minimum point.
    _min.x = std::min(_min.x, box._min.x);
    _min.y = std::min(_min.y, box._min.y);
    _min.z = std::min(_min.z, box._min.z);

    // Calculate the new maximum point.
    _max.x = std::max(_max.x, box._max.x);
    _max.y = std::max(_max.y, box._max.y);
    _max.z = std::max(_max.z, box._max.z);
}

void AABB::set(const Vec3& min, const Vec3& max)
{
    this->_min = min;
    this->_max = max;
}

void AABB::reset()
{
    _min.set(99999.0f, 99999.0f, 99999.0f);
    _max.set(-99999.0f, -99999.0f, -99999.0f);
}

bool AABB::isEmpty() const
{
    return _min.x > _max.x || _min.y > _max.y || _min.z > _max.z;
}

void AABB::updateMinMax(const Vec3* point, ssize_t num)
{
    for (ssize_t i = 0; i < num; i++)
    {
        // Leftmost point.
        if (point[i].x < _min.x)
            _min.x = point[i].x;

        // Lowest point.
        if (point[i].y < _min.y)
            _min.y = point[i].y;

        // Farthest point.
        if (point[i].z < _min.z)
            _min.z = point[i].z;

        // Rightmost point.
        if (point[i].x > _max.x)
            _max.x = point[i].x;

        // Highest point.
        if (point[i].y > _max.y)
            _max.y = point[i].y;

        // Nearest point.
        if (point[i].z > _max.z)
            _max.z = point[i].z;
    }
}

void AABB::transform(const Mat4& mat)
{
    Vec3 corners[8];
    // Near face, specified counter-clockwise
    // Left-top-front.
    corners[0].set(_min.x, _max.y, _max.z);
    // Left-bottom-front.
    corners[1].set(_min.x, _min.y, _max.z);
    // Right-bottom-front.
    corners[2].set(_max.x, _min.y, _max.z);
    // Right-top-front.
    corners[3].set(_max.x, _max.y, _max.z);

    // Far face, specified clockwise
    // Right-top-back.
    corners[4].set(_max.x, _max.y, _min.z);
    // Right-bottom-back.
    corners[5].set(_max.x, _min.y, _min.z);
    // Left-bottom-back.
    corners[6].set(_min.x, _min.y, _min.z);
    // Left-top-back.
    corners[7].set(_min.x, _max.y, _min.z);

    // Transform the corners, recalculate the min and max points along the way.
    for (int i = 0; i < 8; i++)
        mat.transformPoint(&corners[i]);

    reset();

    updateMinMax(corners, 8);
}

}