// ---------------------------------------------------------------------
// Render the tree. Simple no-fan method.
//
public void recursRender(TriTreeNode tri, int leftX, int leftY, int rightX, int rightY, int apexX, int apexY)
{
if (tri != null && tri.getLeftChild() != null) // All non-leaf nodes have both children, so just check for one
{
int centerX = (leftX + rightX) >> 1; // Compute X coordinate of center of Hypotenuse
int centerY = (leftY + rightY) >> 1; // Compute Y coord...
recursRender(tri.getLeftChild(), apexX, apexY, leftX, leftY, centerX, centerY);
recursRender(tri.getRightChild(), rightX, rightY, apexX, apexY, centerX, centerY);
}
else // A leaf node! Output a triangle to be rendered.
{
float leftZ = landscape.getHeightMap(heightX + leftX, heightY + leftY);
float rightZ = landscape.getHeightMap(heightX + rightX, heightY + rightY);
float apexZ = landscape.getHeightMap(heightX + apexX, heightY + apexY);
// Actual number of rendered triangles...
landscape.NumTrisRendered++;
// Perform lighting calculations.
Vector3[] vec = new Vector3[3];
Vector3 normal = new Vector3();
// Create a vertex normal for this triangle.
// NOTE: This is an extremely slow operation for illustration purposes only.
// You should use a texture map with the lighting pre-applied to the texture.
vec[0].X = leftX;
vec[0].Y = leftZ;
vec[0].Z = leftY;
vec[1].X = rightX;
vec[1].Y = rightZ;
vec[1].Z = rightY;
vec[2].X = apexX;
vec[2].Y = apexZ;
vec[2].Z = apexY;
normal = RenderEngine.calcNormal(vec);
normal.Normalize();
float u = ((float)leftX + (float)worldX) / (float)mapSize;
float v = ((float)leftY + (float)worldY) / (float)mapSize;
landscape.Verts[landscape.NumVertsRendered] = new PositionNormalMultiTexture(new Vector3((float)landscape.getPosition().X + worldX + (float)leftX, landscape.getPosition().Y + (float)leftZ, (float)-landscape.getPosition().Z - worldY - (float)leftY), normal, new Vector2(u, v), new Vector2(u, v));
landscape.NumVertsRendered++;
u = ((float)rightX + (float)worldX) / (float)mapSize;
v = ((float)rightY + (float)worldY) / (float)mapSize;
landscape.Verts[landscape.NumVertsRendered] = new PositionNormalMultiTexture(new Vector3((float)landscape.getPosition().X + worldX + (float)rightX, landscape.getPosition().Y + (float)rightZ, (float)-landscape.getPosition().Z - worldY - (float)rightY), normal, new Vector2(u, v), new Vector2(u, v));
landscape.NumVertsRendered++;
u = ((float)apexX + (float)worldX) / (float)mapSize;
v = ((float)apexY + (float)worldY) / (float)mapSize;
landscape.Verts[landscape.NumVertsRendered] = new PositionNormalMultiTexture(new Vector3((float)landscape.getPosition().X + worldX + (float)apexX, landscape.getPosition().Y + (float)apexZ, (float)-landscape.getPosition().Z - worldY - (float)apexY), normal, new Vector2(u, v), new Vector2(u, v));
landscape.NumVertsRendered++;
}
}
// ---------------------------------------------------------------------
// Tessellate a Patch.
// Will continue to split until the variance metric is met.
//
public void recursTessellate(TriTreeNode tri, int leftX, int leftY, int rightX, int rightY, int apexX, int apexY, int node, ushort[] m_CurrentVariance)
{
float triVariance = 0.0f;
int centerX = (leftX + rightX) >> 1; // Compute X coordinate of center of Hypotenuse
int centerY = (leftY + rightY) >> 1; // Compute Y coord...
if (node < (1 << varianceDepth))
{
// Extremely slow distance metric (sqrt is used).
// Replace this with a faster one!
float distance = 1.0f + (float)Math.Sqrt(Math.Pow(centerX - cam.VEye.X, 2) + Math.Pow(centerY + cam.VEye.Z, 2));
// Egads! A division too? What's this world coming to!
// This should also be replaced with a faster operation.
triVariance = ((float)m_CurrentVariance[node] * mapSize * 2) / distance; // Take both distance and variance into consideration
}
if ((node >= (1 << varianceDepth)) || // IF we do not have variance info for this node, then we must have gotten here by splitting, so continue down to the lowest level.
(triVariance > landscape.FrameVariance)) // OR if we are not below the variance tree, test for variance.
{
split(tri); // Split this triangle.
if (tri != null && tri.getLeftChild() != null && // If this triangle was split, try to split it's children as well.
((Math.Abs(leftX - rightX) >= 2) || (Math.Abs(leftY - rightY) >= 2))) // Tessellate all the way down to one vertex per height field entry
{
recursTessellate(tri.getLeftChild(), apexX, apexY, leftX, leftY, centerX, centerY, node << 1, m_CurrentVariance);
recursTessellate(tri.getRightChild(), rightX, rightY, apexX, apexY, centerX, centerY, 1 + (node << 1), m_CurrentVariance);
}
}
}
// ---------------------------------------------------------------------
// Split a single Triangle and link it into the mesh.
// Will correctly force-split diamonds.
//
public void split(TriTreeNode tri)
{
if (tri != null)
{
// We are already split, no need to do it again.
if (tri.getLeftChild() != null)
{
return;
}
// If this triangle is not in a proper diamond, force split our base neighbor
if (tri.getBaseNeighbor() != null && tri.getBaseNeighbor().getBaseNeighbor() != tri)
{
split(tri.getBaseNeighbor());
}
// Create children and link into mesh
tri.setLeftChild(landscape.allocateTri());
tri.setRightChild(landscape.allocateTri());
// If creation failed, just exit.
if (tri.getLeftChild() == null)
{
return;
}
if (tri.getRightChild() == null)
{
return;
}
// Fill in the information we can get from the parent (neighbor pointers)
tri.getLeftChild().setBaseNeighbor(tri.getLeftNeighbor());
tri.getLeftChild().setLeftNeighbor(tri.getRightChild());
tri.getRightChild().setBaseNeighbor(tri.getRightNeighbor());
tri.getRightChild().setRightNeighbor(tri.getLeftChild());
// Link our Left Neighbor to the new children
if (tri.getLeftNeighbor() != null)
{
if (tri.getLeftNeighbor().getBaseNeighbor() == tri)
{
tri.getLeftNeighbor().setBaseNeighbor(tri.getLeftChild());
}
else if (tri.getLeftNeighbor().getLeftNeighbor() == tri)
{
tri.getLeftNeighbor().setLeftNeighbor(tri.getLeftChild());
}
else if (tri.getLeftNeighbor().getRightNeighbor() == tri)
{
tri.getLeftNeighbor().setRightNeighbor(tri.getLeftChild());
}
else
{
;// Illegal Left Neighbor!
}
}
// Link our Right Neighbor to the new children
if (tri.getRightNeighbor() != null)
{
if (tri.getRightNeighbor().getBaseNeighbor() == tri)
{
tri.getRightNeighbor().setBaseNeighbor(tri.getRightChild());
}
else if (tri.getRightNeighbor().getRightNeighbor() == tri)
{
tri.getRightNeighbor().setRightNeighbor(tri.getRightChild());
}
else if (tri.getRightNeighbor().getLeftNeighbor() == tri)
{
tri.getRightNeighbor().setLeftNeighbor(tri.getRightChild());
}
else
{
;// Illegal Right Neighbor!
}
}
// Link our Base Neighbor to the new children
if (tri.getBaseNeighbor() != null)
{
if (tri.getBaseNeighbor().getLeftChild() != null)
{
tri.getBaseNeighbor().getLeftChild().setRightNeighbor(tri.getRightChild());
tri.getBaseNeighbor().getRightChild().setLeftNeighbor(tri.getLeftChild());
tri.getLeftChild().setRightNeighbor(tri.getBaseNeighbor().getRightChild());
tri.getRightChild().setLeftNeighbor(tri.getBaseNeighbor().getLeftChild());
}
else
{
split(tri.getBaseNeighbor()); // Base Neighbor (in a diamond with us) was not split yet, so do that now.
}
}
else
{
// An edge triangle, trivial case.
tri.getLeftChild().setRightNeighbor(null);
tri.getRightChild().setLeftNeighbor(null);
}
}
}
