Method Simulate

engine/Poseidon/World/Simulation/Cloth/ClothObject.cpp:67–273

#define G_CONST 9.8066f

void ClothObject::Simulate(Matrix4Val pos,      // world space position of fixed points
                           Vector3Val velocity, // world space velocity of fixed points
                           float time, Vector3Par wind, Vector3Par inertia, SimulationImportance importance)
{
    if (!EnableVisualEffects(pos.Position(), importance))
    {
        InitPos(pos, velocity);
        return;
    }

    // create acceleration array
    int nKnots = _knots.W() * _knots.H();
    AUTO_STATIC_ARRAY(Vector3, accel, 64 * 64);
    accel.Realloc(nKnots);
    accel.Resize(nKnots);
    // init acceleration of all knots with gravity
    Vector3 grav(0, -G_CONST * _gravCoef, 0);

    struct Neighbourh
    {
        int dx, dy;
        float factor;
        int align;
    };
    static const Neighbourh neighbourhs[] = {{-1, 0, 1.0f},  {+1, 0, 1.0f},  {0, -1, 1.0f},  {0, +1, 1.0f},
                                             {-1, -1, 0.5f}, {+1, +1, 0.5f}, {-1, +1, 0.5f}, {+1, -1, 0.5f}};
    // calculate stretch forces
    const float xGrid = _xSize / (_knots.W() - 1);
    const float yGrid = _ySize / (_knots.H() - 1);
    const int nNeighbourhs = sizeof(neighbourhs) / sizeof(*neighbourhs);

    struct NormNeighbourh
    {
        int dx1, dy1;
        int dx2, dy2;
    };
    static const NormNeighbourh normNeighbourhs[] = {
        {-1, 0, 0, +1},
        {0, +1, +1, 0},
        {+1, 0, 0, -1},
        {0, -1, -1, 0},
    };
    const int nNormNeighbourhs = sizeof(normNeighbourhs) / sizeof(*normNeighbourhs);

    while (time > 0)
    {
        float maxStep = _maxStep;
        float step = floatMin(time, maxStep);
        time -= maxStep;

        for (int i = 0; i < nKnots; i++)
        {
            accel[i] = grav;
        }

        for (int y = 0; y < _knots.H(); y++)
        {
            for (int x = 0; x < _knots.W(); x++)