private void CreateCap(float dTheta, ref int vidx, ref int iIdx, Vector3 normal, float y)
{
int start = vidx;
CyCoord coords = new CyCoord(0, y, radius);
//pole
vertices[vidx++] = new MeshVertex(position: new Vector3(0, coords.Y, 0),
normal: normal,
tangent: new Vector3(1, 0, 0),
texCoord: new Vector2(0.5f, 0.5f));
for (int i = 0; i <= slices; i++)
{
coords.Theta = i * dTheta;
vertices[vidx++] = CreateVertex(coords, dTheta);
}
for (int i = 0; i < slices; i++)
{
//create triangle
if (normal.Y == 1)
{
indices[iIdx++] = (ushort)(start + i + 1);
indices[iIdx++] = (ushort)(start);
indices[iIdx++] = (ushort)(start + i + 2);
}
else
{
indices[iIdx++] = (ushort)start;
indices[iIdx++] = (ushort)(start + i + 1);
indices[iIdx++] = (ushort)(start + i + 2);
}
}
}
private void GenerateGeometry()
{
vertices = new MeshVertex[(stacks + 1) * (slices + 1) + (slices + 1) + 1];
indices = new ushort[(stacks) * slices * 6 + slices * 3];
float dTheta = Numerics.TwoPI / (float)slices;
float dy = height / (float)stacks;
int vidx = 0;
int iIdx = 0;
float halfHeight = height * 0.5f;
CyCoord coords = new CyCoord(0, halfHeight, radius);
//vertices[vidx++] = new MeshVertex(position: new Vector3(0, coords.Y, 0),
// normal: new Vector3(0, 1, 0),
// tangent: new Vector3(1, 0, 0),
// texCoord: new Vector2(0.5f, 0.5f));
CreateCap(dTheta, ref vidx, ref iIdx, new Vector3(0, -1, 0), -coords.Y);
ushort offset = (ushort)vidx;
for (int i = 0; i <= stacks; i++)
{
coords.Y = halfHeight - i * dy;
coords.Radius = Numerics.Lerp(0, radius, (i * dy) / height);
for (int j = 0; j <= slices; j++)
{
coords.Theta = j * dTheta;
vertices[vidx++] = CreateVertex(coords, dTheta);
}
}
int numRingVertices = slices + 1;
for (int i = 0; i < stacks; i++)
{
for (int j = 0; j < slices; j++)
{
indices[iIdx++] = (ushort)(offset + (ushort)(i * numRingVertices + j));
indices[iIdx++] = (ushort)(offset + (ushort)(i * numRingVertices + j + 1));
indices[iIdx++] = (ushort)(offset + (ushort)((i + 1) * numRingVertices + j));
indices[iIdx++] = (ushort)(offset + (ushort)((i + 1) * numRingVertices + j));
indices[iIdx++] = (ushort)(offset + (ushort)(i * numRingVertices + j + 1));
indices[iIdx++] = (ushort)(offset + (ushort)((i + 1) * numRingVertices + j + 1));
}
}
//for (int i = 0; i < slices; i++)
//{
// //create triangle
// indices[iIdx++] = (ushort)(offset + i);
// indices[iIdx++] = (ushort)0;
// indices[iIdx++] = (ushort)(offset + i + 1);
//}
}
private unsafe MeshVertex CreateVertex(CyCoord coords, float dTheta)
{
Vector3 *pos = stackalloc Vector3[3];
CyCoord tcoord = coords;
for (int i = 0; i < 3; i++)
{
//compute 3 positions for computing the derivate respect theta
pos[i] = tcoord.ToCartesian();
tcoord.Theta += dTheta;
}
var tangent = Vector3.Normalize(Numerics.DerivateForward1(pos, dTheta));
var normal = Vector3.Normalize(Vector3.Cross(tangent, new Vector3(0, -1, 0)));
var texCoord = new Vector2(coords.Theta / Numerics.TwoPI, 0.5f - coords.Y / height);
return(new MeshVertex(pos[0], normal, tangent, texCoord));
}
private void Build()
{
vertices = new MeshVertex[(stacks + 1) * (slices + 1) + (open ? 0 : 2 * (slices + 1) + 2)];
indices = new ushort[stacks * slices * 6 + (open ? 0 : slices * 6)];
float dTheta = Numerics.TwoPI / (float)slices;
float dy = height / stacks;
int vidx = 0;
int iIdx = 0;
float halfHeight = height * 0.5f;
CyCoord coords = new CyCoord(0, halfHeight, radius);
if (!open)
{
CreateCap(dTheta, ref vidx, ref iIdx, new Vector3(0, 1, 0), coords.Y);
CreateCap(dTheta, ref vidx, ref iIdx, new Vector3(0, -1, 0), -coords.Y);
}
ushort offset = (ushort)vidx;
for (int i = 0; i <= stacks; i++)
{
coords.Y = halfHeight - i * dy;
for (int j = 0; j <= slices; j++)
{
coords.Theta = j * dTheta;
vertices[vidx++] = CreateVertex(coords, dTheta);
}
}
int numRingVertices = slices + 1;
for (int i = 0; i < stacks; i++)
{
for (int j = 0; j < slices; j++)
{
indices[iIdx++] = (ushort)(offset + (ushort)(i * numRingVertices + j));
indices[iIdx++] = (ushort)(offset + (ushort)(i * numRingVertices + j + 1));
indices[iIdx++] = (ushort)(offset + (ushort)((i + 1) * numRingVertices + j));
indices[iIdx++] = (ushort)(offset + (ushort)((i + 1) * numRingVertices + j));
indices[iIdx++] = (ushort)(offset + (ushort)(i * numRingVertices + j + 1));
indices[iIdx++] = (ushort)(offset + (ushort)((i + 1) * numRingVertices + j + 1));
}
}
}
private void Generate()
{
vertices = new MeshVertex[slices + 1];
float step = Numerics.TwoPI / slices;
CyCoord coords = new CyCoord(Numerics.PIover2, 0, radius);
for (int i = 0; i <= slices; i++)
{
coords.Theta = i * step;
vertices[i] = new MeshVertex(position: coords.ToCartesian());
}
indices = new ushort[slices * 2];
for (int i = 0; i < slices; i++)
{
indices[2 * i] = (ushort)i;
indices[2 * i + 1] = (ushort)(i + 1);
}
}
