urho3d/Engine/Math/Sphere.h

//
// Urho3D Engine
// Copyright (c) 2008-2011 Lasse Öörni
//
// 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 "Vector3.h"

class BoundingBox;
class Polyhedron;
class Frustum;

/// %Sphere in three-dimensional space.
class Sphere
{
public:
    /// Construct undefined.
    Sphere() :
        center_(Vector3::ZERO),
        radius_(0.0f),
        defined_(false)
    {
    }
    
    /// Copy-construct from another sphere.
    Sphere(const Sphere& sphere) :
        center_(sphere.center_),
        radius_(sphere.radius_),
        defined_(sphere.defined_)
    {
    }
    
    /// Construct from center and radius.
    Sphere(const Vector3& center, float radius) :
        center_(center),
        radius_(radius),
        defined_(true)
    {
    }
    
    /// Construct from an array of vertices.
    Sphere(const Vector3* vertices, unsigned count) :
        defined_(false)
    {
        Define(vertices, count);
    }
    
    /// Construct from a bounding box.
    Sphere(const BoundingBox& box) :
        defined_(false)
    {
        Define(box);
    }
    
    /// Construct from a frustum.
    Sphere(const Frustum& frustum) :
        defined_(false)
    {
        Define(frustum);
    }
    
    /// Construct from a polyhedron.
    Sphere(const Polyhedron& poly) :
        defined_(false)
    {
        Define(poly);
    }
    
    /// Assign from another sphere.
    Sphere& operator = (const Sphere& rhs)
    {
        center_ = rhs.center_;
        radius_ = rhs.radius_;
        defined_ = rhs.defined_;
        return *this;
    }
    
    /// Test for equality with another sphere.
    bool operator == (const Sphere& rhs) const { return center_ == rhs.center_ && radius_ == rhs.radius_; }
    /// Test for inequality with another sphere.
    bool operator != (const Sphere& rhs) const { return center_ != rhs.center_ || radius_ != rhs.radius_; }
    
    /// Define from another sphere.
    void Define(const Sphere& sphere)
    {
        Define(sphere.center_, sphere.radius_);
    }
    
    /// Define from center and radius.
    void Define(const Vector3& center, float radius)
    {
        center_ = center;
        radius_ = radius;
        defined_ = true;
    }
    
    /// Define from an array of vertices.
    void Define(const Vector3* vertices, unsigned count);
    /// Define from a bounding box.
    void Define(const BoundingBox& box);
    /// Define from a frustum.
    void Define(const Frustum& frustum);
    /// Define from a polyhedron.
    void Define(const Polyhedron& poly);
    
    /// Merge a point.
    void Merge(const Vector3& point)
    {
        if (!defined_)
        {
            center_ = point;
            radius_ = 0.0f;
            defined_ = true;
            return;
        }
        
        Vector3 offset = point - center_;
        float dist = offset.Length();
        
        if (dist > radius_)
        {
            float half = (dist - radius_) * 0.5f;
            radius_ += half;
            center_ += (half / dist) * offset;
        }
    }
    
    /// Merge an array of vertices.
    void Merge(const Vector3* vertices, unsigned count);
    /// Merge a bounding box.
    void Merge(const BoundingBox& box);
    /// Merge a frustum.
    void Merge(const Frustum& frustum);
    /// Merge a polyhedron.
    void Merge(const Polyhedron& poly);
    /// Merge a sphere.
    void Merge(const Sphere& sphere);
    
    /// Clear to undefined state.
    void Clear()
    {
        center_ = Vector3::ZERO;
        radius_ = 0.0f;
        defined_ = false;
    }
    
    /// Test if a point is inside.
    Intersection IsInside(const Vector3& point) const
    {
        float distSquared = (point - center_).LengthSquared();
        if (distSquared < radius_ * radius_)
            return INSIDE;
        else
            return OUTSIDE;
    }
    
    /// Test if another sphere is inside, outside or intersects.
    Intersection IsInside(const Sphere& sphere) const
    {
        float dist = (sphere.center_ - center_).Length();
        if (dist >= sphere.radius_ + radius_)
            return OUTSIDE;
        else if (dist + sphere.radius_ < radius_)
            return INSIDE;
        else
            return INTERSECTS;
    }
    
    /// Test if another sphere is (partially) inside or outside.
    Intersection IsInsideFast(const Sphere& sphere) const
    {
        float distSquared = (sphere.center_ - center_).LengthSquared();
        float combined = sphere.radius_ + radius_;
        
        if (distSquared >= combined * combined)
            return OUTSIDE;
        else
            return INSIDE;
    }
    
    /// Test if a bounding box is inside, outside or intersects.
    Intersection IsInside(const BoundingBox& box) const;
    /// Test if a bounding box is (partially) inside or outside.
    Intersection IsInsideFast(const BoundingBox& box) const;
    
    /// Return distance of a point to the surface, or 0 if inside.
    float Distance(const Vector3& point) const { return Max((point - center_).Length() - radius_, 0.0f); }
    
    /// Return distance of a point to the surface, or 0 if inside, using fast square root.
    float DistanceFast(const Vector3& point) const { return Max((point - center_).LengthFast() - radius_, 0.0f); }
    
    /// Sphere center.
    Vector3 center_;
    /// Sphere radius.
    float radius_;
    /// Defined flag.
    bool defined_;
};