metaforce/Runtime/Collision/CAreaOctTree.cpp

#include "CAreaOctTree.hpp"
#include "CMaterialFilter.hpp"
#include "zeus/CVector2i.hpp"
#include <array>

namespace urde
{

static bool _close_enough(float f1, float f2, float epsilon)
{
    return std::fabs(f1 - f2) <= epsilon;
}

static bool BoxLineTest(const zeus::CAABox& aabb, const zeus::CLine& line, float& lT, float& hT)
{
    const float* aabbMin = &aabb.min.x;
    const float* aabbMax = &aabb.max.x;
    const float* lorigin = &line.origin.x;
    const float* ldir = &line.dir.x;

    for (int i=0 ; i<3 ; ++i)
    {
        if (_close_enough(*ldir, 0.f, 0.000099999997f))
            if (*lorigin < *aabbMin || *lorigin > *aabbMax)
                return false;

        if (*ldir < 0.f)
        {
            if (*aabbMax - *lorigin < lT * *ldir)
                lT = *aabbMax - *lorigin * 1.f / *ldir;
            if (*aabbMin - *lorigin > hT * *ldir)
                hT = *aabbMin - *lorigin * 1.f / *ldir;
        }
        else
        {
            if (*aabbMin - *lorigin > lT * *ldir)
                lT = *aabbMin - *lorigin * 1.f / *ldir;
            if (*aabbMax - *lorigin < hT * *ldir)
                hT = *aabbMax - *lorigin * 1.f / *ldir;
        }

        ++aabbMin;
        ++aabbMax;
        ++lorigin;
        ++ldir;
    }

    return lT <= hT;
}

static const int SomeIndexA[] =
{
    1, 2, 4
};

static const int SomeIndexB[] =
{
    1, 2, 0
};

static const int SomeIndexC[8][8] =
{
    {0, 1, 2, 4, 5, 6, 8, 0xA},
    {0, 1, 2, 3, 5, 6, 8, 0xA},
    {0, 1, 2, 4, 5, 6, 9, 0xB},
    {0, 1, 2, 3, 5, 6, 9, 0xC},
    {0, 1, 2, 4, 5, 7, 8, 0xD},
    {0, 1, 2, 3, 5, 7, 8, 0xE},
    {0, 1, 2, 4, 5, 7, 9, 0xF},
    {0, 1, 2, 3, 5, 7, 9, 0xF}
};

static const std::pair<int, std::array<int, 3>> SubdivIndex[16] =
{
    {0, {0, 0, 0}},
    {1, {0, 0, 0}},
    {1, {1, 0, 0}},
    {2, {0, 1, 0}},
    {2, {1, 0, 0}},
    {1, {2, 0, 0}},
    {2, {0, 2, 0}},
    {2, {2, 0, 0}},
    {2, {2, 1, 0}},
    {2, {1, 2, 0}},
    {3, {0, 2, 1}},
    {3, {1, 0, 2}},
    {3, {0, 1, 2}},
    {3, {2, 1, 0}},
    {3, {2, 0, 1}},
    {3, {1, 2, 0}}
};

bool CAreaOctTree::Node::LineTestInternal(const zeus::CLine& line, const CMaterialFilter& filter,
                                          float lT, float hT, float maxT, const zeus::CVector3f& vec) const
{
    float lowT = (1.f - FLT_EPSILON * 100.f) * lT;
    float highT = (1.f + FLT_EPSILON * 100.f) * hT;
    if (maxT != 0.f)
    {
        if (lowT < 0.f)
            lowT = 0.f;
        if (highT > maxT)
            highT = maxT;
        if (lowT > highT)
            return true;
    }

    if (x20_nodeType == ETreeType::Leaf)
    {
        TriListReference triList = GetTriangleArray();
        for (u16 i=0 ; i<triList.GetSize() ; ++i)
        {
            CCollisionSurface triangle = x1c_owner.GetMasterListTriangle(triList.GetAt(i));

            // https://en.wikipedia.org/wiki/Möller–Trumbore_intersection_algorithm
            // Find vectors for two edges sharing V0
            zeus::CVector3f e0 = triangle.GetVert(1) - triangle.GetVert(0);
            zeus::CVector3f e1 = triangle.GetVert(2) - triangle.GetVert(0);

            // Begin calculating determinant - also used to calculate u parameter
            zeus::CVector3f P = line.dir.cross(e1);
            float det = P.dot(e0);

            // If determinant is near zero, ray lies in plane of triangle
            // or ray is parallel to plane of triangle
            if (std::fabs(det) < (FLT_EPSILON * 10.f))
                continue;
            float invDet = 1.f / det;

            // Calculate distance from V1 to ray origin
            zeus::CVector3f T = line.origin - triangle.GetVert(0);

            // Calculate u parameter and test bound
            float u = invDet * T.dot(P);

            // The intersection lies outside of the triangle
            if (u < 0.f || u > 1.f)
                continue;

            // Prepare to test v parameter
            zeus::CVector3f Q = T.cross(e0);

            // Calculate T parameter and test bound
            float t = invDet * Q.dot(e1);
            if (t >= highT || t < lowT)
                continue;

            // Calculate V parameter and test bound
            float v = invDet * Q.dot(line.dir);
            if (v < 0.f || u + v > 1.f)
                continue;

            // Do material filter
            CMaterialList matList(triangle.GetSurfaceFlags());
            if (filter.Passes(matList))
                return false;
        }
    }
    else if (x20_nodeType == ETreeType::Branch)
    {
        if (GetChildFlags() == 0xA) // 2 leaves
        {
            for (int i=0 ; i<2 ; ++i)
            {
                Node child = GetChild(i);
                float tf1 = lT;
                float tf2 = hT;
                if (BoxLineTest(child.GetBoundingBox(), line, tf1, tf2))
                    if (!LineTestInternal(line, filter, tf1, tf2, maxT, vec))
                        return false;
            }
            return true;
        }

        zeus::CVector3f center = x0_aabb.center();

        zeus::CVector3f r6 = line.origin + lT * line.dir;
        zeus::CVector3f r7 = line.origin + hT * line.dir;
        zeus::CVector3f r9 = vec * (center - line.origin);

        int r28 = 0;
        int r25 = 0;
        int r26 = 0;
        for (int i=0 ; i<3 ; ++i)
        {
            if (r6[i] >= center[i])
                r28 |= SomeIndexA[i];
            if (r7[i] >= center[i])
                r25 |= SomeIndexA[i];
            if (r9[i] < r9[SomeIndexB[i]])
                r26 |= SomeIndexA[i];
        }

        float f21 = lT;
        int r26b = r28;
        const std::pair<int, std::array<int, 3>>& idx = SubdivIndex[SomeIndexC[r26][r28 ^ r25]];
        for (int i=0 ; i<=idx.first ; ++i)
        {
            float f22 = (i < idx.first) ? r9[idx.second[i]] : hT;
            if (f22 > lowT && f21 <= f22)
            {
                Node child = GetChild(r26b);
                if (child.x20_nodeType != ETreeType::Invalid)
                    if (!LineTestInternal(line, filter, f21, f22, maxT, vec))
                        return false;
            }
            if (i < idx.first)
                r26b ^= 1 << idx.second[i];
            f21 = f22;
        }
    }

    return true;
}

void CAreaOctTree::Node::LineTestExInternal(const zeus::CLine& line, const CMaterialFilter& filter,
                                            SRayResult& res, float lT, float hT, float maxT,
                                            const zeus::CVector3f& vec) const
{
    float lowT = (1.f - FLT_EPSILON * 100.f) * lT;
    float highT = (1.f + FLT_EPSILON * 100.f) * hT;
    if (maxT != 0.f)
    {
        if (lowT < 0.f)
            lowT = 0.f;
        if (highT > maxT)
            highT = maxT;
        if (lowT > highT)
            return;
    }

    if (x20_nodeType == ETreeType::Leaf)
    {
        TriListReference triList = GetTriangleArray();
        float f30 = highT;
        bool foundTriangle = false;
        SRayResult tmpRes;

        for (u16 i=0 ; i<triList.GetSize() ; ++i)
        {
            CCollisionSurface triangle = x1c_owner.GetMasterListTriangle(triList.GetAt(i));

            // https://en.wikipedia.org/wiki/Möller–Trumbore_intersection_algorithm
            // Find vectors for two edges sharing V0
            zeus::CVector3f e0 = triangle.GetVert(1) - triangle.GetVert(0);
            zeus::CVector3f e1 = triangle.GetVert(2) - triangle.GetVert(0);

            // Begin calculating determinant - also used to calculate u parameter
            zeus::CVector3f P = line.dir.cross(e1);
            float det = P.dot(e0);

            // If determinant is near zero, ray lies in plane of triangle
            // or ray is parallel to plane of triangle
            if (std::fabs(det) < (FLT_EPSILON * 10.f))
                continue;
            float invDet = 1.f / det;

            // Calculate distance from V1 to ray origin
            zeus::CVector3f T = line.origin - triangle.GetVert(0);

            // Calculate u parameter and test bound
            float u = invDet * T.dot(P);

            // The intersection lies outside of the triangle
            if (u < 0.f || u > 1.f)
                continue;

            // Prepare to test v parameter
            zeus::CVector3f Q = T.cross(e0);

            // Calculate T parameter and test bound
            float t = invDet * Q.dot(e1);
            if (t >= f30 || t < lowT)
                continue;

            // Calculate V parameter and test bound
            float v = invDet * Q.dot(line.dir);
            if (v < 0.f || u + v > 1.f)
                continue;

            // Do material filter
            CMaterialList matList(triangle.GetSurfaceFlags());
            if (filter.Passes(matList) && t <= f30)
            {
                f30 = t;
                foundTriangle = true;
                tmpRes.x10_surface.emplace(triangle);
                tmpRes.x3c_t = t;
            }
        }

        if (foundTriangle)
        {
            res = tmpRes;
            res.x0_plane = res.x10_surface->GetPlane();
        }
    }
    else if (x20_nodeType == ETreeType::Branch)
    {
        if (GetChildFlags() == 0xA) // 2 leaves
        {
            SRayResult tmpRes[2];
            for (int i=0 ; i<2 ; ++i)
            {
                Node child = GetChild(i);
                float tf1 = lT;
                float tf2 = hT;
                if (BoxLineTest(child.GetBoundingBox(), line, tf1, tf2))
                    LineTestExInternal(line, filter, tmpRes[i], tf1, tf2, maxT, vec);
            }

            if (!tmpRes[0].x10_surface && !tmpRes[1].x10_surface)
            {
                res = SRayResult();
            }
            else if (tmpRes[0].x10_surface && tmpRes[1].x10_surface)
            {
                if (tmpRes[0].x3c_t < tmpRes[1].x3c_t)
                    res = tmpRes[0];
                else
                    res = tmpRes[1];
            }
            else if (tmpRes[0].x10_surface)
            {
                res = tmpRes[0];
            }
            else
            {
                res = tmpRes[1];
            }

            if (res.x3c_t > highT)
                res = SRayResult();

            return;
        }

        zeus::CVector3f center = x0_aabb.center(); // r26

        zeus::CVector3f r25 = line.origin + lT * line.dir;
        zeus::CVector3f r24 = line.origin + hT * line.dir;
        int r19[] = {-1, -1, -1, 0};
        float r20[3];

        int r17 = 0;
        for (int i=0 ; i<3 ; ++i)
        {
            if (r25[i] < center[i] || r24[i] <= center[i])
                if (r24[i] >= center[i] || r25[i] <= center[i])
                    continue;
            if (_close_enough(line.dir[i], 0.f, 0.000099999997f))
                continue;
            r19[r17++] = i;
            r20[i] = vec[i] * (center[i] - line.origin[i]);
        }

        switch (r17)
        {
        default:
            return;
        case 0:
        case 1:
            break;
        case 2:
            if (r20[r19[1]] < r20[r19[0]])
                std::swap(r19[1], r19[0]);
            break;
        case 3:
            if (r20[0] < r20[1])
            {
                if (r20[0] >= r20[2])
                {
                    r19[0] = 2;
                    r19[1] = 0;
                    r19[2] = 1;
                }
                else if (r20[1] < r20[2])
                {
                    r19[0] = 0;
                    r19[1] = 1;
                    r19[2] = 2;
                }
                else
                {
                    r19[0] = 0;
                    r19[1] = 2;
                    r19[2] = 1;
                }
            }
            else
            {
                if (r20[1] >= r20[2])
                {
                    r19[0] = 2;
                    r19[1] = 1;
                    r19[2] = 0;
                }
                else if (r20[0] < r20[2])
                {
                    r19[0] = 1;
                    r19[1] = 0;
                    r19[2] = 2;
                }
                else
                {
                    r19[0] = 1;
                    r19[1] = 2;
                    r19[2] = 0;
                }
            }
            break;
        }

        zeus::CVector3f lineEnd = line.origin + (lT * line.dir);
        int selector = 0;
        if (lineEnd.x >= center.x)
            selector = 1;
        if (lineEnd.y >= center.y)
            selector |= 1 << 1;
        if (lineEnd.z >= center.z)
            selector |= 1 << 2;

        float loT = lT;
        for (int i=-1 ; i<r17 ; ++i)
        {
            if (i >= 0)
                selector ^= 1 << r19[i];
            float hiT = (i < r17-1) ? hiT = r20[r19[i+1]] : hiT = hT;
            if (hiT > lowT && loT <= hiT)
            {
                Node child = GetChild(selector);
                if (child.x20_nodeType != ETreeType::Invalid)
                    LineTestExInternal(line, filter, res, loT, hiT, maxT, vec);
                if (res.x10_surface)
                    if (res.x3c_t > highT)
                        res = SRayResult();
            }
            loT = hiT;
        }
    }
}

bool CAreaOctTree::Node::LineTest(const zeus::CLine& line, const CMaterialFilter& filter, float length) const
{
    if (x20_nodeType == ETreeType::Invalid)
        return true;

    float f1 = 0.f;
    float f2 = 0.f;
    if (!BoxLineTest(x0_aabb, line, f1, f2))
        return true;

    zeus::CVector3f recip = 1.f / line.dir;
    return LineTestInternal(line, filter, f1 - 0.000099999997f, f2 + 0.000099999997f, length, recip);
}

void CAreaOctTree::Node::LineTestEx(const zeus::CLine& line, const CMaterialFilter& filter,
                                    SRayResult& res, float length) const
{
    if (x20_nodeType == ETreeType::Invalid)
        return;

    float f1 = 0.f;
    float f2 = 0.f;
    if (!BoxLineTest(x0_aabb, line, f1, f2))
        return;

    zeus::CVector3f recip = 1.f / line.dir;
    LineTestExInternal(line, filter, res, f1 - 0.000099999997f, f2 + 0.000099999997f, length, recip);
}

CAreaOctTree::Node CAreaOctTree::Node::GetChild(int idx) const
{
    u16 flags = *reinterpret_cast<const u16*>(x18_ptr);
    const u32* offsets = reinterpret_cast<const u32*>(x18_ptr + 4);
    ETreeType type = ETreeType((flags >> (2 * idx)) & 0x3);

    if (type == ETreeType::Branch)
    {
        zeus::CAABox pos, neg, res;
        x0_aabb.splitZ(pos, neg);
        if (idx & 4)
        {
            pos.splitY(pos, neg);
            if (idx & 2)
            {
                pos.splitX(pos, neg);
                if (idx & 1)
                    res = pos;
                else
                    res = neg;
            }
            else
            {
                neg.splitX(pos, neg);
                if (idx & 1)
                    res = pos;
                else
                    res = neg;
            }
        }
        else
        {
            neg.splitY(pos, neg);
            if (idx & 2)
            {
                pos.splitX(pos, neg);
                if (idx & 1)
                    res = pos;
                else
                    res = neg;
            }
            else
            {
                neg.splitX(pos, neg);
                if (idx & 1)
                    res = pos;
                else
                    res = neg;
            }
        }

        return Node(x18_ptr + offsets[idx] + 36, res, x1c_owner, ETreeType::Branch);
    }
    else if (type == ETreeType::Leaf)
    {
        const float* aabb = reinterpret_cast<const float*>(x18_ptr + offsets[idx] + 36);
        zeus::CAABox aabbObj(aabb[0], aabb[1], aabb[2], aabb[3], aabb[4], aabb[5]);
        return Node(aabb, aabbObj, x1c_owner, ETreeType::Leaf);
    }
    else
    {
        return Node(nullptr, zeus::CAABox::skNullBox, x1c_owner, ETreeType::Invalid);
    }
}

void CAreaOctTree::SwapTreeNode(u8* ptr, Node::ETreeType type)
{
    if (type == Node::ETreeType::Branch)
    {
        u16* typeBits = reinterpret_cast<u16*>(ptr);
        *typeBits = hecl::SBig(*typeBits);
        u32* offsets = reinterpret_cast<u32*>(ptr + 4);

        for (int i=0 ; i<8 ; ++i)
        {
            Node::ETreeType ctype = Node::ETreeType((*typeBits >> (2 * i)) & 0x3);
            offsets[i] = hecl::SBig(offsets[i]);
            SwapTreeNode(ptr + offsets[i] + 36, ctype);
        }
    }
    else if (type == Node::ETreeType::Leaf)
    {
        float* aabb = reinterpret_cast<float*>(ptr);
        aabb[0] = hecl::SBig(aabb[0]);
        aabb[1] = hecl::SBig(aabb[1]);
        aabb[2] = hecl::SBig(aabb[2]);
        aabb[3] = hecl::SBig(aabb[3]);
        aabb[4] = hecl::SBig(aabb[4]);
        aabb[5] = hecl::SBig(aabb[5]);

        u16* countIdxs = reinterpret_cast<u16*>(ptr + 24);
        *countIdxs = hecl::SBig(*countIdxs);
        for (u16 i=0 ; i<*countIdxs ; ++i)
            countIdxs[i+1] = hecl::SBig(countIdxs[i+1]);
    }
}

CAreaOctTree::CAreaOctTree(const zeus::CAABox& aabb, Node::ETreeType treeType, const u8* buf, const u8* treeBuf,
                           u32 matCount, const u32* materials, const u8* vertMats, const u8* edgeMats, const u8* polyMats,
                           u32 edgeCount, const CCollisionEdge* edges, u32 polyCount, const u16* polyEdges,
                           u32 vertCount, const float* verts)
: x0_aabb(aabb), x18_treeType(treeType), x1c_buf(buf), x20_treeBuf(treeBuf),
  x24_matCount(matCount), x28_materials(materials), x2c_vertMats(vertMats),
  x30_edgeMats(edgeMats), x34_polyMats(polyMats), x38_edgeCount(edgeCount),
  x3c_edges(edges), x40_polyCount(polyCount), x44_polyEdges(polyEdges),
  x48_vertCount(vertCount), x4c_verts(verts)
{
    SwapTreeNode(const_cast<u8*>(x20_treeBuf), treeType);

    for (u32 i=0 ; i<matCount ; ++i)
        const_cast<u32*>(x28_materials)[i] = hecl::SBig(x28_materials[i]);

    for (u32 i=0 ; i<edgeCount ; ++i)
        const_cast<CCollisionEdge*>(x3c_edges)[i].swapBig();

    for (u32 i=0 ; i<polyCount ; ++i)
        const_cast<u16*>(x44_polyEdges)[i] = hecl::SBig(x44_polyEdges[i]);

    for (u32 i=0 ; i<vertCount*3 ; ++i)
        const_cast<float*>(x4c_verts)[i] = hecl::SBig(x4c_verts[i]);
}

std::unique_ptr<CAreaOctTree> CAreaOctTree::MakeFromMemory(const u8* buf, unsigned int size)
{
    athena::io::MemoryReader r(buf + 8, size - 8);
    r.readUint32Big();
    r.readUint32Big();
    zeus::CAABox aabb;
    aabb.readBoundingBoxBig(r);
    Node::ETreeType nodeType = Node::ETreeType(r.readUint32Big());
    u32 treeSize = r.readUint32Big();
    const u8* cur = reinterpret_cast<const u8*>(buf) + 8 + r.position();

    const u8* treeBuf = cur;
    cur += treeSize;

    u32 matCount = hecl::SBig(*reinterpret_cast<const u32*>(cur));
    cur += 4;
    const u32* matBuf = reinterpret_cast<const u32*>(cur);
    cur += 4 * matCount;

    u32 vertMatsCount = hecl::SBig(*reinterpret_cast<const u32*>(cur));
    cur += 4;
    const u8* vertMatsBuf = cur;
    cur += vertMatsCount;

    u32 edgeMatsCount = hecl::SBig(*reinterpret_cast<const u32*>(cur));
    cur += 4;
    const u8* edgeMatsBuf = cur;
    cur += edgeMatsCount;

    u32 polyMatsCount = hecl::SBig(*reinterpret_cast<const u32*>(cur));
    cur += 4;
    const u8* polyMatsBuf = cur;
    cur += polyMatsCount;

    u32 edgeCount = hecl::SBig(*reinterpret_cast<const u32*>(cur));
    cur += 4;
    const CCollisionEdge* edgeBuf = reinterpret_cast<const CCollisionEdge*>(cur);
    cur += edgeCount * sizeof(edgeCount);

    u32 polyCount = hecl::SBig(*reinterpret_cast<const u32*>(cur));
    cur += 4;
    const u16* polyBuf = reinterpret_cast<const u16*>(cur);
    cur += polyCount * 2;

    u32 vertCount = hecl::SBig(*reinterpret_cast<const u32*>(cur));
    cur += 4;
    const float* vertBuf = reinterpret_cast<const float*>(cur);

    return std::make_unique<CAreaOctTree>(aabb, nodeType, reinterpret_cast<const u8*>(buf + 8), treeBuf,
                                          matCount, matBuf, vertMatsBuf, edgeMatsBuf, polyMatsBuf,
                                          edgeCount, edgeBuf, polyCount, polyBuf, vertCount, vertBuf);
}

CCollisionSurface CAreaOctTree::GetMasterListTriangle(u16 idx) const
{
    const CCollisionEdge& e0 = x3c_edges[x44_polyEdges[idx*3]];
    const CCollisionEdge& e1 = x3c_edges[x44_polyEdges[idx*3+1]];
    u16 vert2 = e1.GetVertIndex2();
    if (e1.GetVertIndex1() != e0.GetVertIndex1())
        if (e1.GetVertIndex1() != e0.GetVertIndex2())
            vert2 = e1.GetVertIndex1();

    u32 material = x28_materials[x34_polyMats[idx]];
    if (material & 0x2000000)
        return CCollisionSurface(GetVert(e0.GetVertIndex2()), GetVert(e0.GetVertIndex1()),
                                 GetVert(vert2), material);
    else
        return CCollisionSurface(GetVert(e0.GetVertIndex1()), GetVert(e0.GetVertIndex2()),
                                 GetVert(vert2), material);
}

void CAreaOctTree::GetTriangleVertexIndices(u16 idx, u16 indicesOut[3]) const
{
    const CCollisionEdge& e0 = x3c_edges[x44_polyEdges[idx*3]];
    const CCollisionEdge& e1 = x3c_edges[x44_polyEdges[idx*3+1]];
    indicesOut[2] =
        (e1.GetVertIndex1() != e0.GetVertIndex1() && e1.GetVertIndex1() != e0.GetVertIndex2()) ?
        e1.GetVertIndex1() : e1.GetVertIndex2();

    u32 material = x28_materials[x34_polyMats[idx]];
    if (material & 0x2000000)
    {
        indicesOut[0] = e0.GetVertIndex2();
        indicesOut[1] = e0.GetVertIndex1();
    }
    else
    {
        indicesOut[0] = e0.GetVertIndex1();
        indicesOut[1] = e0.GetVertIndex2();
    }
}

}