List <IndexTriangle> StitchCircles(List <IndexedVertex> circle1, List <IndexedVertex> circle2)
{
// Create triangles that connect circle1 to circle2, forming a band of a surface.
if (circle1.Count != circle2.Count)
{
throw new System.Exception("Circles do not have the same number of vertices.");
}
List <IndexTriangle> triangles = new List <IndexTriangle>();
for (int i = 0; i < circle1.Count; i++)
{
// Create the triangles that have 2 points each on circle1.
// These all have the ordering (c2[i], c1[i+1], c1[i]).
int iPlus = (i + 1) % circle1.Count;
IndexedVertex iv1 = circle2[i];
IndexedVertex iv2 = circle1[iPlus];
IndexedVertex iv3 = circle1[i];
IndexTriangle tri = new IndexTriangle(iv1, iv2, iv3);
triangles.Add(tri);
// Create the triangles that have 2 points each on circle2.
// These have the ordering (c2[i], c2[i+1], c1[i+1].
iv1 = circle2[i];
iv2 = circle2[iPlus];
iv3 = circle1[iPlus];
tri = new IndexTriangle(iv1, iv2, iv3);
triangles.Add(tri);
}
return(triangles);
}
List <IndexTriangle> CloseCylinderCaps(CylinderMesh cylinder, List <IndexedVertex> verts)
{
List <IndexTriangle> triangles = new List <IndexTriangle>();
List <IndexedVertex> bottomCircle = cylinder.circleCuts[0];
List <IndexedVertex> topCircle = cylinder.circleCuts[cylinder.circleCuts.Count - 1];
// Compute center point of bottom circle.
Vector3 bottomCenter = Vector3.zero;
foreach (IndexedVertex v in bottomCircle)
{
bottomCenter += v.vertex;
}
bottomCenter /= bottomCircle.Count;
// Compute center point of top circle.
Vector3 topCenter = Vector3.zero;
foreach (IndexedVertex v in topCircle)
{
topCenter += v.vertex;
}
topCenter /= topCircle.Count;
// Add the two points to the mesh.
IndexedVertex bottomCenterVert = new IndexedVertex(bottomCenter, currentIndex);
currentIndex++;
IndexedVertex topCenterVert = new IndexedVertex(topCenter, currentIndex);
currentIndex++;
verts.Add(bottomCenterVert);
verts.Add(topCenterVert);
// Add triangle fans.
for (int i = 0; i < bottomCircle.Count; i++)
{
// Bottom circle gets CCW order
int iPlus = (i + 1) % bottomCircle.Count;
IndexedVertex i1 = bottomCenterVert;
IndexedVertex i2 = bottomCircle[i];
IndexedVertex i3 = bottomCircle[iPlus];
IndexTriangle tri = new IndexTriangle(i1, i2, i3);
triangles.Add(tri);
}
for (int i = 0; i < topCircle.Count; i++)
{
// Top circle gets CW order
int iPlus = (i + 1) % topCircle.Count;
IndexedVertex i1 = topCenterVert;
IndexedVertex i2 = topCircle[iPlus];
IndexedVertex i3 = topCircle[i];
IndexTriangle tri = new IndexTriangle(i1, i2, i3);
triangles.Add(tri);
}
return(triangles);
}
List <IndexTriangle> stitchCylinderEnds(CylinderMesh outer, CylinderMesh inner)
{
if (outer.circleCuts.Count != inner.circleCuts.Count)
{
throw new System.Exception("Cylinders do not have same number of cuts.");
}
int numCuts = outer.circleCuts.Count;
List <IndexTriangle> triangles = new List <IndexTriangle>();
List <IndexedVertex> topOuter = outer.circleCuts[numCuts - 1];
List <IndexedVertex> topInner = inner.circleCuts[numCuts - 1];
topVerts = topOuter.ConvertAll <Vector3>(new Converter <IndexedVertex, Vector3>(IndexedVertex.toVector3));
if (topOuter.Count != topInner.Count)
{
throw new System.Exception("Circles do not have same number of vertices.");
}
// Since the cuts are not necessarily aligned (in the case of curvature
// or torsion changes), we want to stitch using the closest pairs of vertices.
// Since we start with outer vertex i = 0, find the index of the inner vertex
// closest to outer 0.
Vector3 outer0top = topOuter[0].vertex;
int topInnerOffset = 0;
float closestDistance = Vector3.Distance(outer0top, topInner[0].vertex);
for (int i = 0; i < topInner.Count; i++)
{
float dist = Vector3.Distance(topInner[i].vertex, outer0top);
if (dist < closestDistance)
{
closestDistance = dist;
topInnerOffset = i;
}
}
// To join the top rim, we need to add the triangles with
// counterclockwise ordering, since the vertices are clockwise
// when viewed from below (not above).
for (int outerI = 0; outerI < topOuter.Count; outerI++)
{
int outerIPlus = (outerI + 1) % topOuter.Count;
int innerI = (outerI + topInnerOffset) % topInner.Count;
int innerIPlus = (innerI + 1) % topInner.Count;
// The triangles with two vertices in the outer circle have
// the order outer[i], inner[i], outer[i+1].
IndexedVertex iv1 = topOuter[outerI];
IndexedVertex iv2 = topInner[innerI];
IndexedVertex iv3 = topOuter[outerIPlus];
IndexTriangle tri = new IndexTriangle(iv1, iv2, iv3);
triangles.Add(tri);
// The triangles with two vertices in the inner circle have
// the order inner[i], inner[i+1], outer[i+1].
iv1 = topInner[innerI];
iv2 = topInner[innerIPlus];
iv3 = topOuter[outerIPlus];
tri = new IndexTriangle(iv1, iv2, iv3);
triangles.Add(tri);
}
List <IndexedVertex> bottomOuter = outer.circleCuts[0];
List <IndexedVertex> bottomInner = inner.circleCuts[0];
bottomVerts = bottomOuter.ConvertAll <Vector3>(new Converter <IndexedVertex, Vector3>(IndexedVertex.toVector3));
if (bottomOuter.Count != bottomInner.Count)
{
throw new System.Exception("Circles do not have same number of vertices.");
}
// Same procedure as top ring: find starting vertex closest to
// vertex 0 of outer ring.
Vector3 outer0bottom = bottomOuter[0].vertex;
int bottomInnerOffset = 0;
closestDistance = Vector3.Distance(outer0bottom, bottomInner[0].vertex);
for (int i = 0; i < bottomInner.Count; i++)
{
float dist = Vector3.Distance(bottomInner[i].vertex, outer0bottom);
if (dist < closestDistance)
{
closestDistance = dist;
bottomInnerOffset = i;
}
}
// To join the bottom faces, we add triangles with vertices in clockwise order.
for (int outerI = 0; outerI < bottomOuter.Count; outerI++)
{
int outerIPlus = (outerI + 1) % bottomOuter.Count;
int innerI = (outerI + bottomInnerOffset) % bottomInner.Count;
int innerIPlus = (innerI + 1) % bottomInner.Count;
// The triangles with two vertices in the outer circle have
// the order outer[i], outer[i+1], inner[i].
IndexedVertex iv1 = bottomOuter[outerI];
IndexedVertex iv2 = bottomOuter[outerIPlus];
IndexedVertex iv3 = bottomInner[innerI];
IndexTriangle tri = new IndexTriangle(iv1, iv2, iv3);
triangles.Add(tri);
// The triangles with two vertices in the inner circle have
// the order inner[i], outer[i+1], inner[i+1].
iv1 = bottomInner[innerI];
iv2 = bottomOuter[outerIPlus];
iv3 = bottomInner[innerIPlus];
tri = new IndexTriangle(iv1, iv2, iv3);
triangles.Add(tri);
}
return(triangles);
}