Method GetCollisionTriangles

Source/Engine/Terrain/TerrainPatch.cpp:2449–2543

}

void TerrainPatch::GetCollisionTriangles(const BoundingSphere& bounds, Array<Vector3>& result)
{
    PROFILE_CPU();
    PROFILE_MEM(LevelTerrain);
    result.Clear();

    // Skip if no intersection with patch
    if (!CollisionsHelper::BoxIntersectsSphere(GetBounds(), bounds) || !_physicsHeightField)
        return;

    // Prepare
    const auto& triangles = GetCollisionTriangles();
    const float size = _terrain->_chunkSize * TERRAIN_UNITS_PER_VERTEX * Terrain::ChunksCountEdge;
    Transform transform;
    transform.Translation = _offset + Vector3(0, _yOffset, 0);
    transform.Orientation = Quaternion::Identity;
    transform.Scale = Vector3(1.0f, _yHeight, 1.0f);
    transform = _terrain->_transform.LocalToWorld(transform);
    Matrix world;
    transform.GetWorld(world);
    Matrix invWorld;
    Matrix::Invert(world, invWorld);

    // Project bounds to terrain surface XZ plane to find the heightfield range that might intersect with the brush
    BoundingBox box;
    BoundingBox::FromSphere(bounds, box);
    Vector3 min, max;
    Vector3::Transform(box.Minimum, invWorld, min);
    Vector3::Transform(box.Maximum, invWorld, max);
    {
        Vector3 t = min;
        Vector3::Min(t, max, min);
        Vector3::Max(t, max, max);
    }

    // Normalize bounds and map to actual triangles buffer
    int32 rows, cols;
    PhysicsBackend::GetHeightFieldSize(_physicsHeightField, rows, cols);
    int32 startRow = (int32)Math::Floor(min.X / size * rows);
    int32 startCol = (int32)Math::Floor(min.Z / size * cols);
    int32 endRow = (int32)Math::Ceil(max.X / size * rows);
    int32 endCol = (int32)Math::Ceil(max.Z / size * cols);

    // Normalize bounds to patch borders
    startRow = Math::Clamp(startRow, 0, rows - 2);
    startCol = Math::Clamp(startCol, 0, cols - 2);
    endRow = Math::Clamp(endRow, 0, rows - 2);
    endCol = Math::Clamp(endCol, 0, cols - 2);

    // Shortcut: row=x, col=z

    // Check every triangle from the given range
    for (int32 row = startRow; row <= endRow; row++)
    {
        for (int32 col = startCol; col <= endCol; col++)
        {
            int32 index = (row * (cols - 1) + col) * 6;
            Vector3 t0 = triangles[index + 0];