Question

我正在使用OpenGL和C ++开发3D游戏，我需要一些信息和帮助来了解如何计算OBB（Oriented Bounding Box）之间的碰撞（OBB vs OBB，OBB vs其他早期。）

我知道构成每个对象的边界框的8个顶点（乘以模型矩阵并在“世界”中获得位置）;现在需要知道如何计算OBB之间的碰撞。

Answer 1

如果只需要知道对象是否碰撞，那么用于两个3D OBB之间的简单碰撞检测的分离轴定理的C ++代码实现将是：

struct vec3 
{
    float x, y, z;
    vec3 operator- (const vec3 & rhs) const { return{ x - rhs.x, y - rhs.y, z - rhs.z }; }
    float operator* (const vec3 & rhs) const { return{ x * rhs.x + y * rhs.y + z * rhs.z }; } // DOT PRODUCT
    vec3 operator^ (const vec3 & rhs) const { return{ y * rhs.z - z * rhs.y, z * rhs.x - x * rhs.z, x * rhs.y - y * rhs.x }; } // CROSS PRODUCT
    vec3 operator* (const float& rhs)const { return vec3{ x * rhs, y * rhs, z * rhs }; }
};

struct OBB
{
    vec3 Pos, AxisX, AxisY, AxisZ, Half_size;
};

bool getSeparatingPlane(const vec3& RPos, const vec3 Plane, const OBB& box1, const OBB&box2)
{
    return (fabs(RPos*Plane) > (fabs((box1.AxisX*box1.Half_size.x)*Plane) + fabs((box1.AxisY*box1.Half_size.y)*Plane) + fabs((box1.AxisZ*box1.Half_size.z)*Plane) +
    fabs((box2.AxisX*box2.Half_size.x)*Plane) + fabs((box2.AxisY*box2.Half_size.y)*Plane) + fabs((box2.AxisZ*box2.Half_size.z)*Plane)));
}

bool getCollision(const OBB& box1, const OBB&box2)
{
    static vec3 RPos;
    RPos = box2.Pos - box1.Pos;

    if (getSeparatingPlane(RPos, box1.AxisX, box1, box2) || getSeparatingPlane(RPos, box1.AxisY, box1, box2) || getSeparatingPlane(RPos, box1.AxisZ, box1, box2) ||
getSeparatingPlane(RPos, box2.AxisX, box1, box2) || getSeparatingPlane(RPos, box2.AxisY, box1, box2) || getSeparatingPlane(RPos, box2.AxisZ, box1, box2) ||
getSeparatingPlane(RPos, box1.AxisX^box2.AxisX, box1, box2) || getSeparatingPlane(RPos, box1.AxisX^box2.AxisY, box1, box2) ||
getSeparatingPlane(RPos, box1.AxisX^box2.AxisZ, box1, box2) || getSeparatingPlane(RPos, box1.AxisY^box2.AxisX, box1, box2) ||
getSeparatingPlane(RPos, box1.AxisY^box2.AxisY, box1, box2) || getSeparatingPlane(RPos, box1.AxisY^box2.AxisZ, box1, box2) ||
getSeparatingPlane(RPos, box1.AxisZ^box2.AxisX, box1, box2) || getSeparatingPlane(RPos, box1.AxisZ^box2.AxisY, box1, box2) ||
getSeparatingPlane(RPos, box1.AxisZ^box2.AxisZ, box1, box2)) return false;

    return true;
}

int _tmain(int argc, _TCHAR* argv[])
{
    OBB A, B;

    A.Pos = { 0.f, 0.f, 0.f };
    A.Half_size = {10.f, 1.f, 1.f};
    A.AxisX = { 1.f, 0.f, 0.f };
    A.AxisY = { 0.f, 1.f, 0.f };
    A.AxisZ = { 0.f, 0.f, 1.f };

    B.Pos = { 10.f, 0.f, 0.f };
    B.Half_size = {10.f, 1.f, 1.f};
    B.AxisX = { 1.f, 0.f, 0.f };
    B.AxisY = { 0.f, 1.f, 0.f };
    B.AxisZ = { 0.f, 0.f, 1.f };

    if (getCollision(A, B)) std::cout << "Collision!!!" << std::endl;
    else std::cout << "No collision." << std::endl;

    std::cout << std::endl;
    system("pause");
    return 0;
}

计算边界框冲突Oriented C ++ opengl

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