private void CalculateGeometry()
{
double phiSeg = 2 * Math.PI / nSegments;
// The center of the top and bottom
Points.Add(new Point3D(0, 0, radius / 2));
Points.Add(new Point3D(0, 0, -radius / 2));
// Points along the edge
for (double iphi = 0; iphi < 2 * Math.PI; iphi += phiSeg)
{
double x = radius * Math.Cos(iphi);
double y = radius * Math.Sin(iphi);
double z = height / 2;
Points.Add(new Point3D(x, y, z)); // Top ring is all even numbers, starting at 2 to 2 * nSegments
Points.Add(new Point3D(x, y, -z)); // Bottom ring is all odd numbers, starting at 3 to 2 * nSegments + 1
}
const int topCenterIndex = 0;
const int bottomCenterIndex = 1;
const int firstTopRing = 2;
int lastTopRing = 2 * nSegments;
// Top
for (int index = firstTopRing; index <= lastTopRing; index += 2)
{
int nextIndex = index == lastTopRing ? firstTopRing : index + 2;
// Top circle
TriangleIndices.Add(index);
TriangleIndices.Add(nextIndex);
TriangleIndices.Add(topCenterIndex);
// Bottom circle - opposite orientation to face out
TriangleIndices.Add(index + 1);
TriangleIndices.Add(bottomCenterIndex);
TriangleIndices.Add(nextIndex + 1);
// Sides
TriangleIndices.Add(index);
TriangleIndices.Add(index + 1);
TriangleIndices.Add(nextIndex);
TriangleIndices.Add(index + 1);
TriangleIndices.Add(nextIndex + 1);
TriangleIndices.Add(nextIndex);
}
}
public void AddTriangleIndex(uint index)
{
if (_pointTally == 0)
{
_fanStartIndex = index;
}
if (_pointTally < 3) //first time
{
TriangleIndices.Add(Offset(index));
// _meshGeometry.Positions.Add(_points[(int)index]);
}
else
{
switch (_meshType)
{
case TriangleType.GL_Triangles: // 0x0004
TriangleIndices.Add(Offset(index));
break;
case TriangleType.GL_Triangles_Strip: // 0x0005
if (_pointTally % 2 == 0)
{
TriangleIndices.Add(Offset(_previousToLastIndex));
TriangleIndices.Add(Offset(_lastIndex));
}
else
{
TriangleIndices.Add(Offset(_lastIndex));
TriangleIndices.Add(Offset(_previousToLastIndex));
}
TriangleIndices.Add(Offset(index));
break;
case TriangleType.GL_Triangles_Fan: // 0x0006
TriangleIndices.Add(Offset(_fanStartIndex));
TriangleIndices.Add(Offset(_lastIndex));
TriangleIndices.Add(Offset(index));
break;
default:
break;
}
}
_previousToLastIndex = _lastIndex;
_lastIndex = index;
_pointTally++;
}
private void CalculateGeometry()
{
double thetaSeg = Math.PI / nSegments;
double phiSeg = 2 * Math.PI / nSegments;
Points.Add(new Point3D(0, 0, radius));
for (double itheta = thetaSeg; itheta < Math.PI; itheta += thetaSeg)
{
for (double iphi = 0; iphi < 2 * Math.PI; iphi += phiSeg)
{
double x = radius * Math.Cos(iphi) * Math.Sin(itheta);
double y = radius * Math.Sin(iphi) * Math.Sin(itheta);
double z = radius * Math.Cos(itheta);
Points.Add(new Point3D(x, y, z));
}
}
Points.Add(new Point3D(0, 0, -radius));
// Top ring
for (int index = 1; index <= nSegments; ++index)
{
TriangleIndices.Add(0);
TriangleIndices.Add(index);
TriangleIndices.Add(index == nSegments ? 1 : index + 1);
}
// Middle section
int maxTheta = nSegments * (nSegments - 2); // Index of the last point of the second-to-last theta ring
for (int thetaIndex = 1; thetaIndex <= maxTheta; thetaIndex += nSegments)
{
for (int phiIndex = 0; phiIndex < nSegments; ++phiIndex)
{
int thisPoint = thetaIndex + phiIndex;
int nextPhi = phiIndex == nSegments - 1 ? thetaIndex : thisPoint + 1;
int nextTheta = thisPoint + nSegments;
int nextThetaPhi = nextPhi + nSegments;
TriangleIndices.Add(thisPoint);
TriangleIndices.Add(nextTheta);
TriangleIndices.Add(nextThetaPhi);
TriangleIndices.Add(thisPoint);
TriangleIndices.Add(nextThetaPhi);
TriangleIndices.Add(nextPhi);
}
}
// Bottom ring
int lastThetaRing = maxTheta + 1;
int lastIndex = nSegments * (nSegments - 1) + 1;
for (int index = lastThetaRing; index < lastIndex; ++index)
{
TriangleIndices.Add(lastIndex);
TriangleIndices.Add(index == lastIndex - 1 ? lastThetaRing : index + 1);
TriangleIndices.Add(index);
}
}