void Extrude(const Vec3* points, int numPoints, std::vector<Vec3>& vertices, std::vector<Vec3>& normals, std::vector<int>& triangles, float radius, int resolution, int smoothing)
{
if (numPoints < 2)
return;
Vec3 u, v;
Vec3 w = SafeNormalize(Vec3(points[1])-Vec3(points[0]), Vec3(0.0f, 1.0f, 0.0f));
BasisFromVector(w, &u, &v);
Matrix44 frame;
frame.SetCol(0, Vec4(u.x, u.y, u.z, 0.0f));
frame.SetCol(1, Vec4(v.x, v.y, v.z, 0.0f));
frame.SetCol(2, Vec4(w.x, w.y, w.z, 0.0f));
frame.SetCol(3, Vec4(0.0f, 0.0f, 0.0f, 1.0f));
for (int i=0; i < numPoints -1; ++i)
{
Vec3 next;
if (i < numPoints -1)
next = Normalize(Vec3(points[i+1])-Vec3(points[i-1]));
else
next = Normalize(Vec3(points[i])-Vec3(points[i-1]));
int a = Max(i-1, 0);
int b = i;
int c = Min(i+1, numPoints -1);
int d = Min(i+2, numPoints -1);
Vec3 p1 = Vec3(points[b]);
Vec3 p2 = Vec3(points[c]);
Vec3 m1 = 0.5f*(Vec3(points[c]) - Vec3(points[a]));
Vec3 m2 = 0.5f*(Vec3(points[d]) - Vec3(points[b]));
// ensure last segment handled correctly
int segments = (i < numPoints-2)?smoothing:smoothing+1;
for (int s=0; s < segments; ++s)
{
Vec3 pos = HermiteInterpolate(p1, p2, m1, m2, s/float(smoothing));
Vec3 dir = Normalize(HermiteTangent(p1, p2, m1, m2, s/float(smoothing)));
Vec3 cur = frame.GetAxis(2);
const float angle = acosf(Dot(cur, dir));
// if parallel then don't need to do anything
if (fabsf(angle) > 0.001f)
frame = RotationMatrix(angle, SafeNormalize(Cross(cur, dir)))*frame;
int startIndex = vertices.size();
for (int c=0; c < resolution; ++c)
{
float angle = k2Pi / resolution;
// transform position and normal to world space
Vec4 v = frame*Vec4(cosf(angle*c), sinf(angle*c), 0.0f, 0.0f);
vertices.push_back(Vec3(v)*radius + pos);
normals.push_back(Vec3(v));
}
// output triangles
if (startIndex != 0)
{
for (int i=0; i < resolution; ++i)
{
int curIndex = startIndex + i;
int nextIndex = startIndex + (i+1)%resolution;
triangles.push_back(curIndex);
triangles.push_back(curIndex-resolution);
triangles.push_back(nextIndex-resolution);
triangles.push_back(nextIndex-resolution);
triangles.push_back(nextIndex);
triangles.push_back(curIndex);
}
}
}
}
}
