MortonCode.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 MortonCode
{
public:
    static uint32 sExpandBits(float inV)
    {
        JPH_ASSERT(inV >= 0.0f && inV <= 1.0f);
        uint32 v = uint32(inV * 1023.0f + 0.5f);
        JPH_ASSERT(v < 1024);
        v = (v * 0x00010001u) & 0xFF0000FFu;
        v = (v * 0x00000101u) & 0x0F00F00Fu;
        v = (v * 0x00000011u) & 0xC30C30C3u;
        v = (v * 0x00000005u) & 0x49249249u;
        return v;
    }
 
    static uint32 sGetMortonCode(Vec3Arg inVector, const AABox &inVectorBounds)
    {
        // Convert to 10 bit fixed point
        Vec3 scaled = (inVector - inVectorBounds.mMin) / inVectorBounds.GetSize();
        uint x = sExpandBits(scaled.GetX());
        uint y = sExpandBits(scaled.GetY());
        uint z = sExpandBits(scaled.GetZ());
        return (x << 2) + (y << 1) + z;
    }
};
 
JPH_NAMESPACE_END