SpatialAccelerationCollisionDetector.h

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// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Chaos/Collision/CollisionDetector.h"
#include "Chaos/Collision/CollisionContext.h"
#include "Chaos/Collision/SpatialAccelerationBroadPhase.h"
#include "Chaos/EvolutionResimCache.h"
#include "Chaos/PBDCollisionConstraints.h"
#include "ProfilingDebugging/CsvProfiler.h"
 
namespace Chaos
{
    class FSpatialAccelerationCollisionDetector : public FCollisionDetector
    {
    public:
        FSpatialAccelerationCollisionDetector(FSpatialAccelerationBroadPhase& InBroadPhase, FPBDCollisionConstraints& InCollisionContainer)
            : FCollisionDetector(InCollisionContainer)
            , BroadPhase(InBroadPhase)
        {
        }
 
        FSpatialAccelerationBroadPhase& GetBroadPhase()
        { 
            return BroadPhase;
        }
 
        void RunBroadPhase(const FReal Dt, FEvolutionResimCache* ResimCache)
        {
            if (!GetCollisionContainer().GetCollisionsEnabled())
            {
                return;
            }
 
            GetCollisionContainer().BeginDetectCollisions();
 
            // Run the broadphase and generate a midphase object for every overlapping particle pair
            BroadPhase.ProduceOverlaps(Dt, &GetCollisionContainer().GetConstraintAllocator(), GetCollisionContainer().GetDetectorSettings(), ResimCache);
        }
 
        void RunNarrowPhase(const FReal Dt, FEvolutionResimCache* ResimCache)
        {
            if (!GetCollisionContainer().GetCollisionsEnabled())
            {
                return;
            }
 
            // Run collision detection on the output of the broadphase
            {
                SCOPE_CYCLE_COUNTER(STAT_Collisions_NarrowPhase);
                CSV_SCOPED_TIMING_STAT(PhysicsVerbose, DetectCollisions_NarrowPhase);
                BroadPhase.ProduceCollisions(Dt);
                BroadPhase.GatherConstraints(GetCollisionContainer().GetIsDeterministic());
            }
            GetCollisionContainer().EndDetectCollisions();
 
            // If we have a resim cache restore and save contacts
            if (ResimCache)
            {
                // Ensure we have at least one allocator
                GetCollisionContainer().GetConstraintAllocator().SetMaxContexts(1);
 
                FCollisionContext Context;
                Context.SetSettings(GetCollisionContainer().GetDetectorSettings());
                Context.SetAllocator(GetCollisionContainer().GetConstraintAllocator().GetContextAllocator(0));
 
                GetCollisionContainer().GetConstraintAllocator().AddResimConstraints(ResimCache->GetAndSanitizeConstraints(), Context);
 
                ResimCache->SaveConstraints(GetCollisionContainer().GetConstraints());
            }
        }
 
        virtual void DetectCollisions(const FReal Dt, FEvolutionResimCache* ResimCache) override
        {
            SCOPE_CYCLE_COUNTER(STAT_Collisions_Detect);
            CHAOS_SCOPED_TIMER(DetectCollisions);
            CSV_SCOPED_TIMING_STAT(Chaos, DetectCollisions);
 
            RunBroadPhase(Dt, ResimCache);
            RunNarrowPhase(Dt, ResimCache);
        }
 
    private:
        FSpatialAccelerationBroadPhase& BroadPhase;
    };
}