private double FaceVariance(short v1, short v2, short v3)
{
double MaxVar = 0;
if (Math.Abs(v1 - v2) == 1 || Math.Abs(v3 - v2) == 1)
{
MaxVar = 0; // minimal face, no variance
}
else
{
// find vertice in middle of hypothenuse
short mid_hyp_indice = MidHypVerticeIndice(v1, v3);
// find real elevation in middle of hypothenuse
CustomVertex.PositionTextured vh = this._elevatedVertices[mid_hyp_indice];
Vector3 v = MathEngine.CartesianToSpherical(vh.X, vh.Y, vh.Z);
double real = v.X - this._layerRadius;
// find extrapolated elevation in middle hyp.
float xe = (this._elevatedVertices[v1].X + this._elevatedVertices[v3].X) / 2;
float ye = (this._elevatedVertices[v1].Y + this._elevatedVertices[v3].Y) / 2;
float ze = (this._elevatedVertices[v1].Z + this._elevatedVertices[v3].Z) / 2;
v = MathEngine.CartesianToSpherical(xe, ye, ze);
double extrapolated = v.X - this._layerRadius;
// variance Note: could be done w/out MathEngine by computing raw cartesian distance
MaxVar = real - extrapolated;
// recurse for potential childs until unit face
MaxVar = Math.Max(MaxVar, FaceVariance(v2, mid_hyp_indice, v1));
MaxVar = Math.Max(MaxVar, FaceVariance(v3, mid_hyp_indice, v2));
}
return(MaxVar);
}
private void CreateMesh(
double north,
double south,
double west,
double east,
int samples,
string displacementFile,
ref CustomVertex.PositionTextured[] vertices,
ref short[] indices)
{
int upperBound = samples - 1;
float scaleFactor = (float)1 / upperBound;
double latrange = Math.Abs(north - south);
double lonrange;
if (west < east)
{
lonrange = east - west;
}
else
{
lonrange = 360.0f + east - west;
}
System.Drawing.Bitmap heightMap = null;
try
{
heightMap = (System.Drawing.Bitmap)System.Drawing.Image.FromFile(displacementFile);
}
catch
{}
vertices = new CustomVertex.PositionTextured[samples * samples];
for (int i = 0; i < samples; i++)
{
for (int j = 0; j < samples; j++)
{
double height = m_cloudBaseAltitude * World.Settings.VerticalExaggeration;
if (heightMap != null)
{
double percentX = (double)j / (double)upperBound;
double percentY = (double)i / (double)upperBound;
if (percentX > 1)
{
percentX = 1;
}
if (percentY > 1)
{
percentY = 1;
}
int x = (int)(percentX * (heightMap.Width - 1));
int y = (int)(percentY * (heightMap.Height - 1));
height += m_displacementMultiplier * heightMap.GetPixel(x, y).R;
}
Vector3 pos = MathEngine.SphericalToCartesian(
north - scaleFactor * latrange * i,
west + scaleFactor * lonrange * j,
this.World.EquatorialRadius + height);
vertices[i * samples + j].X = pos.X;
vertices[i * samples + j].Y = pos.Y;
vertices[i * samples + j].Z = pos.Z;
vertices[i * samples + j].Tu = j * scaleFactor;
vertices[i * samples + j].Tv = i * scaleFactor;
}
}
indices = new short[2 * upperBound * upperBound * 3];
for (int i = 0; i < upperBound; i++)
{
for (int j = 0; j < upperBound; j++)
{
indices[(2 * 3 * i * upperBound) + 6 * j] = (short)(i * samples + j);
indices[(2 * 3 * i * upperBound) + 6 * j + 1] = (short)((i + 1) * samples + j);
indices[(2 * 3 * i * upperBound) + 6 * j + 2] = (short)(i * samples + j + 1);
indices[(2 * 3 * i * upperBound) + 6 * j + 3] = (short)(i * samples + j + 1);
indices[(2 * 3 * i * upperBound) + 6 * j + 4] = (short)((i + 1) * samples + j);
indices[(2 * 3 * i * upperBound) + 6 * j + 5] = (short)((i + 1) * samples + j + 1);
}
}
if (heightMap != null)
{
heightMap.Dispose();
}
}
