NvBlastGeometry.h

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#ifndef NVBLASTGEOMETRY_H
#define NVBLASTGEOMETRY_H

#include "NvBlastTypes.h"
#include "NvBlastMath.h"
#include "NvBlastAssert.h"

#include <limits>


namespace Nv {
namespace Blast{


NV_FORCE_INLINE uint32_t findClosestNode(const float point[4], 
    const uint32_t firstGraphNodeIndex, const uint32_t* familyGraphNodeIndexLinks,
    const uint32_t* adjacencyPartition, const uint32_t* adjacentNodeIndices, const uint32_t* adjacentBondIndices,
    const NvBlastBond* assetBonds, const float* bondHealths,
    const NvBlastChunk* assetChunks, const float* supportChunkHealths, const uint32_t* chunkIndices)
{
    // firstGraphNodeIndex could still be the world chunk, however
    // there should be no way a single-node actor that is just the world chunk exists.
    uint32_t nodeIndex = firstGraphNodeIndex;
    // Since there should always be a regular chunk in the graph, it is possible to initialize closestNode
    // as world chunk index but it would always evaluate to some meaningful node index eventually.
    uint32_t closestNode = nodeIndex;
    float minDist = std::numeric_limits<float>().max();

    // find the closest healthy chunk in the graph by its centroid to point distance
    while (!Nv::Blast::isInvalidIndex(nodeIndex))
    {
        if (supportChunkHealths[nodeIndex] > 0.0f)
        {
            uint32_t chunkIndex = chunkIndices[nodeIndex];
            if (!isInvalidIndex(chunkIndex)) // Invalid if this is the world chunk
            {
                const NvBlastChunk& chunk = assetChunks[chunkIndex];
                const float* centroid = chunk.centroid;

                float d[3]; VecMath::sub(point, centroid, d);
                float dist = VecMath::dot(d, d);

                if (dist < minDist)
                {
                    minDist = dist;
                    closestNode = nodeIndex;
                }
            }
        }
        nodeIndex = familyGraphNodeIndexLinks[nodeIndex];
    }

    // as long as the world chunk is not input as a single-node graph actor
    NVBLAST_ASSERT(!isInvalidIndex(chunkIndices[closestNode]));

    bool iterateOnBonds = true;
    if (iterateOnBonds)
    {
        // improve geometric accuracy by looking on which side of the closest bond the point lies
        // expects bond normals to point from the smaller to the larger node index

        nodeIndex = closestNode;
        minDist = std::numeric_limits<float>().max();

        const uint32_t startIndex = adjacencyPartition[nodeIndex];
        const uint32_t stopIndex = adjacencyPartition[nodeIndex + 1];

        for (uint32_t adjacentIndex = startIndex; adjacentIndex < stopIndex; adjacentIndex++)
        {
            const uint32_t neighbourIndex = adjacentNodeIndices[adjacentIndex];
            const uint32_t neighbourChunk = chunkIndices[neighbourIndex];
            if (!isInvalidIndex(neighbourChunk)) // Invalid if neighbor is the world chunk
            {
                const uint32_t bondIndex = adjacentBondIndices[adjacentIndex];
                // do not follow broken bonds, since it means that neighbor is not actually connected in the graph
                if (bondHealths[bondIndex] > 0.0f && supportChunkHealths[neighbourIndex] > 0.0f)
                {
                    const NvBlastBond& bond = assetBonds[bondIndex];

                    const float* centroid = bond.centroid;
                    float d[3]; VecMath::sub(point, centroid, d);
                    float dist = VecMath::dot(d, d);

                    if (dist < minDist)
                    {
                        minDist = dist;
                        float s = VecMath::dot(d, bond.normal);
                        if (nodeIndex < neighbourIndex)
                        {
                            closestNode = s < 0.0f ? nodeIndex : neighbourIndex;
                        }
                        else
                        {
                            closestNode = s < 0.0f ? neighbourIndex : nodeIndex;
                        }
                    }
                }
            }
        }
    }

    return closestNode;
}


NV_FORCE_INLINE uint32_t findClosestNode(const float point[4],
    const uint32_t firstGraphNodeIndex, const uint32_t* familyGraphNodeIndexLinks,
    const uint32_t* adjacencyPartition, const uint32_t* adjacentNodeIndices, const uint32_t* adjacentBondIndices,
    const NvBlastBond* bonds, const float* bondHealths, const uint32_t* chunkIndices)
{
    // firstGraphNodeIndex could still be the world chunk, however
    // there should be no way a single-node actor that is just the world chunk exists.
    uint32_t nodeIndex = firstGraphNodeIndex;
    // Since there should always be a regular chunk in the graph, it is possible to initialize closestNode
    // as world chunk index but it would always evaluate to some meaningful node index eventually.
    uint32_t closestNode = nodeIndex;
    float minDist = std::numeric_limits<float>().max();

    while (!Nv::Blast::isInvalidIndex(nodeIndex))
    {
        const uint32_t startIndex = adjacencyPartition[nodeIndex];
        const uint32_t stopIndex = adjacencyPartition[nodeIndex + 1];

        for (uint32_t adjacentIndex = startIndex; adjacentIndex < stopIndex; adjacentIndex++)
        {
            const uint32_t neighbourIndex = adjacentNodeIndices[adjacentIndex];
            if (nodeIndex < neighbourIndex)
            {
                const uint32_t bondIndex = adjacentBondIndices[adjacentIndex];
                if (bondHealths[bondIndex] > 0.0f)
                {
                    const NvBlastBond& bond = bonds[bondIndex];

                    const float* centroid = bond.centroid;
                    float d[3]; VecMath::sub(point, centroid, d);
                    float dist = VecMath::dot(d, d);

                    if (dist < minDist)
                    {
                        minDist = dist;
                        // if any of the nodes is the world chunk, use the valid one instead
                        if (isInvalidIndex(chunkIndices[neighbourIndex]))
                        {
                            closestNode = nodeIndex;
                        }
                        else if (isInvalidIndex(chunkIndices[nodeIndex]))
                        {
                            closestNode = neighbourIndex;
                        }
                        else
                        {
                            float s = VecMath::dot(d, bond.normal);
                            closestNode = s < 0 ? nodeIndex : neighbourIndex;
                        }
                    }
                }
            }
        }
        nodeIndex = familyGraphNodeIndexLinks[nodeIndex];
    }

    // as long as the world chunk is not input as a single-node graph actor
    NVBLAST_ASSERT(!isInvalidIndex(chunkIndices[closestNode]));
    return closestNode;
}


} // namespace Blast
} // namespace Nv


#endif // NVBLASTGEOMETRY_H