/// <summary>
/// Calculate the sphere-space position of the patch by determining where the center vertex lies on the sphere
/// </summary>
private void CalculatePatchPosition(TerrainNodeSplitItem item)
{
// find the cube position of the center vertex
double x = bounds.Left + bounds.Width / 2;
double y = bounds.Bottom + bounds.Height / 2;
// get the matrix used to rotate the a position to the appropriate cube face
Matrix faceMatrix = CubeFaces.GetFace(bounds.Face).FaceMatrix;
// create the vertex position in cube-space and rotate it to the appropriate face
Position3 cubePosition = new Position3(x, y, 1);
cubePosition.Transform(ref faceMatrix);
// get the vertex position on the unit sphere and rotate it to the appropriate face
Position3 spherePosition = Tools.CubeToSphereMapping(x, y, 1);
spherePosition.Transform(ref faceMatrix);
spherePosition.Normalize();
Vector2 patchPosition = new Vector2(Constants.PatchWidth / 2, Constants.PatchHeight / 2);
if (item == null)
{
// transform the vertex based on the user defined delegate - this returns the height value of the point on the sphere
createPosition(ref spherePosition, ref cubePosition, ref patchPosition, radius, out position);
}
else
{
double h = item.HeightData[(int)((patchPosition.Y + 1) * (Constants.PatchWidth + 2) + (patchPosition.X + 1))];
if (h < 0) h = 0;
position = spherePosition * (radius + h);
}
}
/// <summary>
/// Generate terrain mesh for this node
/// </summary>
public void GenerateMesh(TerrainNodeSplitItem item)
{
// the minus one here is correct: e.g. 3x3 vertices labeled 0, 1, 2: v0.x = 0, v1.x = 0.5, v2.x = 1. The increment = 1 / (3 - 1) = 0.5
double horizontalStep = bounds.Width / (Constants.PatchWidth - 1);
double verticalStep = bounds.Height / (Constants.PatchHeight - 1);
float horizontalTextureStep = 1.0f / (Constants.PatchWidth - 1);
float verticalTextureStep = 1.0f / (Constants.PatchHeight - 1);
float MinX, MinY, MinZ;
float MaxX, MaxY, MaxZ;
// initialize min and max vertex tracking
MinX = MinY = MinZ = 999999;
MaxX = MaxY = MaxZ = -999999;
// get matrix used to transform vertices to the proper cube face
Matrix faceMatrix = CubeFaces.GetFace(bounds.Face).FaceMatrix;
// create vertex storage using user supplied delegate
vertexBuffer = createTerrainNodeVertexBuffer(item.HeightData.Length);
//int cubeVertexIndex = 0;
//CubeVertices = new Vector2[item.HeightData.Length];
hasMeshBorder = false;
int vertexIndex = 0;
int Rows = Constants.PatchHeight;
int Columns = Constants.PatchWidth;
if (item.HeightData.Length > Constants.PatchWidth * Constants.PatchHeight)
{
hasMeshBorder = true;
Rows += 2;
Columns += 2;
}
patchRows = Rows;
patchColumns = Columns;
float v = 0;
double y = bounds.Bottom;
if (hasMeshBorder)
{
v -= verticalTextureStep;
y -= verticalStep;
}
for (int hy = 0; hy < Rows; hy++)
{
float u = 0;
double x = bounds.Left;
if (hasMeshBorder)
{
u -= horizontalTextureStep;
x -= horizontalStep;
}
for (int hx = 0; hx < Columns; hx++)
{
// create the vertex position and rotate it to the appropriate face
Position3 cubePosition = new Position3(x, y, 1);
Position3 spherePosition = Tools.CubeToSphereMapping(x, y, 1);
spherePosition.Transform(ref faceMatrix);
cubePosition.Transform(ref faceMatrix);
// transform the vertex based on the user defined delegate
double height;
Position3 finalPosition;
Vector2 patchPosition = new Vector2(hx, hy);
if (item == null)
CreatePosition(ref spherePosition, ref cubePosition, ref patchPosition, out finalPosition, out height);
else
{
height = item.HeightData[hy * Columns + hx];
if (height < 0) height = 0;
finalPosition = spherePosition * (radius + height);
TranslateToPatchSpace(ref finalPosition);
}
VertexPositionNormalTextureHeight vertex = new VertexPositionNormalTextureHeight();
vertex.Position = (Vector3)finalPosition;
vertex.Height = (float)height;
vertex.Normal = (Vector3)spherePosition;
vertex.TextureCoordinate = new Vector2(u, v);
vertex.Tangent = Vector4.Zero;
vertexBuffer.Vertices[vertexIndex++] = vertex;
// track min and max coordinates, but only for the vertices that will be in the final mesh
if (hx >= 1 && hx < Columns - 1 && hy >= 1 && hy < Rows - 1)
{
if (vertex.Position.X < MinX) MinX = vertex.Position.X;
if (vertex.Position.Y < MinY) MinY = vertex.Position.Y;
if (vertex.Position.Z < MinZ) MinZ = vertex.Position.Z;
if (vertex.Position.X > MaxX) MaxX = vertex.Position.X;
if (vertex.Position.Y > MaxY) MaxY = vertex.Position.Y;
if (vertex.Position.Z > MaxZ) MaxZ = vertex.Position.Z;
}
x += horizontalStep;
u += horizontalTextureStep;
}
y += verticalStep;
v += verticalTextureStep;
}
// create min and max bounding vertices, in patch-space
minVertex = new Vector3(MinX, MinY, MinZ);
maxVertex = new Vector3(MaxX, MaxY, MaxZ);
// calculate normals and tangents
CalculateNormals();
CalculateTangents();
// save vertex buffer changes - this effectively copies the raw data to a vertex buffer on the device
vertexBuffer.CommitChanges(Constants.PatchWidth, Constants.PatchHeight);
}