ObjectVsBroadPhaseLayerFilterTable.h

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// Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2023 Jorrit Rouwe
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <Jolt/Physics/Collision/BroadPhase/BroadPhaseLayer.h>
 
JPH_NAMESPACE_BEGIN
 
class ObjectVsBroadPhaseLayerFilterTable : public ObjectVsBroadPhaseLayerFilter
{
private:
    uint                    GetBit(ObjectLayer inLayer1, BroadPhaseLayer inLayer2) const
    {
        // Calculate at which bit the entry for this pair resides
        return inLayer1 * mNumBroadPhaseLayers + (BroadPhaseLayer::Type)inLayer2;
    }
 
public:
    JPH_OVERRIDE_NEW_DELETE
 
                            ObjectVsBroadPhaseLayerFilterTable(const BroadPhaseLayerInterface &inBroadPhaseLayerInterface, uint inNumBroadPhaseLayers, const ObjectLayerPairFilter &inObjectLayerPairFilter, uint inNumObjectLayers) :
        mNumBroadPhaseLayers(inNumBroadPhaseLayers)
    {
        // Resize table and set all entries to false
        mTable.resize((inNumBroadPhaseLayers * inNumObjectLayers + 7) / 8, 0);
 
        // Loop over all object layer pairs
        for (ObjectLayer o1 = 0; o1 < inNumObjectLayers; ++o1)
            for (ObjectLayer o2 = 0; o2 < inNumObjectLayers; ++o2)
            {
                // Get the broad phase layer for the second object layer
                BroadPhaseLayer b2 = inBroadPhaseLayerInterface.GetBroadPhaseLayer(o2);
                JPH_ASSERT((BroadPhaseLayer::Type)b2 < inNumBroadPhaseLayers);
 
                // If the object layers collide then so should the object and broadphase layer
                if (inObjectLayerPairFilter.ShouldCollide(o1, o2))
                {
                    uint bit = GetBit(o1, b2);
                    mTable[bit >> 3] |= 1 << (bit & 0b111);
                }
            }
    }
 
    virtual bool            ShouldCollide(ObjectLayer inLayer1, BroadPhaseLayer inLayer2) const override
    {
        uint bit = GetBit(inLayer1, inLayer2);
        return (mTable[bit >> 3] & (1 << (bit & 0b111))) != 0;
    }
 
private:
    uint                    mNumBroadPhaseLayers;                       
    Array<uint8>            mTable;                                     
};
 
JPH_NAMESPACE_END