Sphere.h

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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <Jolt/Geometry/AABox.h>
 
JPH_NAMESPACE_BEGIN
 
class [[nodiscard]] Sphere
{
public:
    JPH_OVERRIDE_NEW_DELETE
 
    inline              Sphere() = default;
    inline              Sphere(const Float3 &inCenter, float inRadius)          : mCenter(inCenter), mRadius(inRadius) { }
    inline              Sphere(Vec3Arg inCenter, float inRadius)                : mRadius(inRadius) { inCenter.StoreFloat3(&mCenter); }
 
    inline Vec3         GetSupport(Vec3Arg inDirection) const
    {
        float length = inDirection.Length();
        return length > 0.0f ? Vec3::sLoadFloat3Unsafe(mCenter) + (mRadius/ length) * inDirection : Vec3::sLoadFloat3Unsafe(mCenter);
    }
 
    // Properties
    inline Vec3         GetCenter() const                                       { return Vec3::sLoadFloat3Unsafe(mCenter); }
    inline float        GetRadius() const                                       { return mRadius; }
 
    inline bool         Overlaps(const Sphere &inB) const
    {
        return (Vec3::sLoadFloat3Unsafe(mCenter) - Vec3::sLoadFloat3Unsafe(inB.mCenter)).LengthSq() <= Square(mRadius + inB.mRadius);
    }
 
    inline bool         Overlaps(const AABox &inOther) const
    {
        return inOther.GetSqDistanceTo(GetCenter()) <= Square(mRadius);
    }
 
    inline void         EncapsulatePoint(Vec3Arg inPoint)
    {
        // Calculate distance between point and center
        Vec3 center = GetCenter();
        Vec3 d_vec = inPoint - center;
        float d_sq = d_vec.LengthSq();
        if (d_sq > Square(mRadius))
        {
            // It is further away than radius, we need to widen the sphere
            // The diameter of the new sphere is radius + d, so the new radius is half of that
            float d = sqrt(d_sq);
            float radius = 0.5f * (mRadius + d);
 
            // The center needs to shift by new radius - old radius in the direction of d
            center += (radius - mRadius) / d * d_vec;
 
            // Store new sphere
            center.StoreFloat3(&mCenter);
            mRadius = radius;
        }
    }
 
private:
    Float3              mCenter;
    float               mRadius;
};
 
JPH_NAMESPACE_END