public override void GetMeshData(List <VertexPositionNormalTexture> vertices, List <ushort> indices)
{
int numColumns = DisplayedObject.Shape.Heights.GetLength(0);
int numRows = DisplayedObject.Shape.Heights.GetLength(1);
TerrainShape shape = DisplayedObject.Shape;
//The terrain can be transformed arbitrarily. However, the collision against the triangles is always oriented such that the transformed local
//up vector points in the same direction as the collidable surfaces.
//To make sure the graphics match the terrain collision, try transforming the local space up direction into world space. Treat it as a normal- it requires an adjugate transpose, not a regular transformation.
var normalTransform = Matrix3x3.AdjugateTranspose(DisplayedObject.WorldTransform.LinearTransform);
var reverseWinding = BEPUutilities.Vector3.Dot(normalTransform.Up, DisplayedObject.WorldTransform.LinearTransform.Up) < 0;
for (int j = 0; j < numRows; j++)
{
for (int i = 0; i < numColumns; i++)
{
VertexPositionNormalTexture v;
BEPUutilities.Vector3 position, n;
DisplayedObject.GetPosition(i, j, out position);
shape.GetLocalNormal(i, j, out n);
Matrix3x3.Transform(ref n, ref normalTransform, out n);
n.Normalize();
MathConverter.Convert(ref position, out v.Position);
MathConverter.Convert(ref n, out v.Normal);
if (reverseWinding)
{
Vector3.Negate(ref v.Normal, out v.Normal);
}
v.TextureCoordinate = new Vector2(i, j);
vertices.Add(v);
if (i < numColumns - 1 && j < numRows - 1)
{
if (shape.QuadTriangleOrganization == QuadTriangleOrganization.BottomLeftUpperRight)
{
//v3 v4
//v1 v2
//v1 v2 v3
indices.Add((ushort)(numColumns * j + i));
if (reverseWinding)
{
indices.Add((ushort)(numColumns * (j + 1) + i));
indices.Add((ushort)(numColumns * j + i + 1));
}
else
{
indices.Add((ushort)(numColumns * j + i + 1));
indices.Add((ushort)(numColumns * (j + 1) + i));
}
//v2 v4 v3
indices.Add((ushort)(numColumns * j + i + 1));
if (reverseWinding)
{
indices.Add((ushort)(numColumns * (j + 1) + i));
indices.Add((ushort)(numColumns * (j + 1) + i + 1));
}
else
{
indices.Add((ushort)(numColumns * (j + 1) + i + 1));
indices.Add((ushort)(numColumns * (j + 1) + i));
}
}
else if (shape.QuadTriangleOrganization == QuadTriangleOrganization.BottomRightUpperLeft)
{
//v1 v2 v4
indices.Add((ushort)(numColumns * j + i));
if (reverseWinding)
{
indices.Add((ushort)(numColumns * (j + 1) + i + 1));
indices.Add((ushort)(numColumns * j + i + 1));
}
else
{
indices.Add((ushort)(numColumns * j + i + 1));
indices.Add((ushort)(numColumns * (j + 1) + i + 1));
}
//v1 v4 v3
indices.Add((ushort)(numColumns * j + i));
if (reverseWinding)
{
indices.Add((ushort)(numColumns * (j + 1) + i));
indices.Add((ushort)(numColumns * (j + 1) + i + 1));
}
else
{
indices.Add((ushort)(numColumns * (j + 1) + i + 1));
indices.Add((ushort)(numColumns * (j + 1) + i));
}
}
}
}
}
}