GenericOctree.inl

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// Copyright Epic Games, Inc. All Rights Reserved.
 
/*=============================================================================
    GenericOctree.inl: Generic octree implementation.
=============================================================================*/
 
#pragma once
 
#include "CoreTypes.h"
#include "CoreFwd.h"
#include "Logging/LogMacros.h"
 
class FBoxCenterAndExtent;
class FOctreeChildNodeRef;
class FOctreeChildNodeSubset;
class FOctreeNodeContext;
struct FMath;
 
 
inline bool FOctreeChildNodeSubset::Contains(FOctreeChildNodeRef ChildRef) const
{
    // This subset contains the child if it has all the bits set that are set for the subset containing only the child node.
    const FOctreeChildNodeSubset ChildSubset(ChildRef);
    return (ChildBits & ChildSubset.ChildBits) == ChildSubset.ChildBits;
}
 
inline FOctreeChildNodeSubset FOctreeNodeContext::GetIntersectingChildren(const FBoxCenterAndExtent& QueryBounds) const
{
    FOctreeChildNodeSubset Result;
 
    // Load the query bounding box values as VectorRegisters.
    const VectorRegister QueryBoundsCenter = VectorLoadAligned(&QueryBounds.Center);
    const VectorRegister QueryBoundsExtent = VectorLoadAligned(&QueryBounds.Extent);
    const VectorRegister QueryBoundsMax = VectorAdd(QueryBoundsCenter,QueryBoundsExtent);
    const VectorRegister QueryBoundsMin = VectorSubtract(QueryBoundsCenter,QueryBoundsExtent);
 
    // Compute the bounds of the node's children.
    const VectorRegister BoundsCenter = VectorLoadAligned(&Bounds.Center);
    const VectorRegister BoundsExtent = VectorLoadAligned(&Bounds.Extent);
    const VectorRegister PositiveChildBoundsMin = VectorSubtract(
        VectorAdd(BoundsCenter,VectorLoadFloat1(&ChildCenterOffset)),
        VectorLoadFloat1(&ChildExtent)
        );
    const VectorRegister NegativeChildBoundsMax = VectorAdd(
        VectorSubtract(BoundsCenter,VectorLoadFloat1(&ChildCenterOffset)),
        VectorLoadFloat1(&ChildExtent)
        );
 
    // Intersect the query bounds with the node's children's bounds.
    Result.PositiveChildBits = VectorMaskBits(VectorCompareGT(QueryBoundsMax, PositiveChildBoundsMin)) & 0x7;
    Result.NegativeChildBits = VectorMaskBits(VectorCompareLE(QueryBoundsMin, NegativeChildBoundsMax)) & 0x7;
    return Result;
}
 
inline FOctreeChildNodeRef FOctreeNodeContext::GetContainingChild(const FBoxCenterAndExtent& QueryBounds) const
{
    FOctreeChildNodeRef Result;
 
    // Load the query bounding box values as VectorRegisters.
    const VectorRegister QueryBoundsCenter = VectorLoadAligned(&QueryBounds.Center);
    const VectorRegister QueryBoundsExtent = VectorLoadAligned(&QueryBounds.Extent);
 
    // Compute the bounds of the node's children.
    const VectorRegister BoundsCenter = VectorLoadAligned(&Bounds.Center);
    const VectorRegister ChildCenterOffsetVector = VectorLoadFloat1(&ChildCenterOffset);
    const VectorRegister NegativeCenterDifference = VectorSubtract(QueryBoundsCenter,VectorSubtract(BoundsCenter,ChildCenterOffsetVector));
    const VectorRegister PositiveCenterDifference = VectorSubtract(VectorAdd(BoundsCenter,ChildCenterOffsetVector),QueryBoundsCenter);
 
    // If the query bounds isn't entirely inside the bounding box of the child it's closest to, it's not contained by any of the child nodes.
    const VectorRegister MinDifference = VectorMin(PositiveCenterDifference,NegativeCenterDifference);
    if(VectorAnyGreaterThan(VectorAdd(QueryBoundsExtent,MinDifference),VectorLoadFloat1(&ChildExtent)))
    {
        Result.SetNULL();
    }
    else
    {
        // Return the child node that the query is closest to as the containing child.
        Result.Index = VectorMaskBits(VectorCompareGT(QueryBoundsCenter, BoundsCenter)) & 0x7;
    }
 
    return Result;
}