public CurvedLineStrip(IParametricCurve curve)
{
var last = curve.ParameterLength * N_SUBDIVITION;
var p0 = curve.PositionAt(0f);
totalLength = 0f;
cumulativeLength.Add(totalLength);
pointParameters.Add(0f);
points.Add(p0);
for (var i = 1; i <= last; i++)
{
var t = i * DX;
var p1 = curve.PositionAt(t);
var v = p1 - p0;
totalLength += v.magnitude;
cumulativeLength.Add(totalLength);
pointParameters.Add(t);
points.Add(p1);
p0 = p1;
}
}
public ParametricPoint(IParametricCurve curve, float t)
{
this.curve = curve;
this.t = t;
}
public Tube(
IParametricCurve curve,
float radius,
int sliceCount,
int stackCount
)
{
float tStep = 1.0f / 512.0f;
// Compute initial N
Vector3 pos = curve.PositionAt(0.0f);
Vector3 posNext = curve.PositionAt(0.0f + tStep);
Vector3 posNext2 = curve.PositionAt(0.0f + tStep + tStep);
Vector3 d1 = posNext - pos;
Vector3 d2 = (posNext2 - posNext) - d1;
Vector3 T = Vector3.Normalize(d1);
Vector3 N = Vector3.Normalize(d2);
Vector3 B = Vector3.Normalize(Vector3.Cross(T, N));
N = Vector3.Normalize(Vector3.Cross(B, T));
var pointLocations = PointAttributes.FindOrCreate <Vector3>("point_locations");
var pointNormals = PointAttributes.FindOrCreate <Vector3>("point_normals");
var pointTexCoords = PointAttributes.FindOrCreate <Vector2>("point_texcoords");
var cornerNormals = CornerAttributes.FindOrCreate <Vector3>("corner_normals");
//var cornerTexCoords = CornerAttributes.FindOrCreate<Vector2>("corner_texcoords");
/* Other vertices */
List <Point> points = new List <Point>();
for (int stack = 0; stack <= stackCount; ++stack)
{
float t = (float)stack / (float)stackCount;
pos = curve.PositionAt(t);
posNext = curve.PositionAt(t + tStep);
d1 = posNext - pos;
T = Vector3.Normalize(d1);
B = Vector3.Normalize(Vector3.Cross(T, N));
N = Vector3.Normalize(Vector3.Cross(B, T));
for (int slice = 0; slice < sliceCount; ++slice)
{
float relPhi = (float)slice / (float)sliceCount;
float phi = (float)System.Math.PI * 2.0f * relPhi;
float sinPhi = (float)System.Math.Sin(phi);
float cosPhi = (float)System.Math.Cos(phi);
Vector3 v = pos;
v += N * sinPhi * radius;
v += B * cosPhi * radius;
Point point = MakePoint();
pointLocations[point] = v;
pointNormals [point] = N * sinPhi + B * cosPhi;
pointTexCoords[point] = new Vector2(relPhi, t);
points.Add(point);
}
}
/* Bottom parts */
{
Vector3 bottomPosition = curve.PositionAt(0.0f);
Vector3 bottomPositionNext = curve.PositionAt(tStep);
Vector3 bottomTangent = Vector3.Normalize(bottomPosition - bottomPositionNext);
Polygon polygon = MakePolygon();
for (int slice = 0; slice < sliceCount; ++slice)
{
int stack = 0;
int reverseSlice = sliceCount - 1 - slice;
Corner corner = polygon.MakeCorner(
points[(stack * (sliceCount)) + reverseSlice]
);
cornerNormals[corner] = bottomTangent;
}
}
/* Middle quads, t = 0 ... t = 1 */
for (int stack = 0; stack < stackCount; ++stack)
{
int nextStack = stack + 1;
for (int slice = 0; slice < sliceCount; ++slice)
{
int nextSlice = (slice + 1) % sliceCount;
MakePolygon(
points[(nextStack * (sliceCount)) + nextSlice],
points[(nextStack * (sliceCount)) + slice],
points[(stack * (sliceCount)) + slice],
points[(stack * (sliceCount)) + nextSlice]
);
}
}
/* Top parts */
{
Vector3 topPosition = curve.PositionAt(1.0f);
Vector3 topPositionPrev = curve.PositionAt(1.0f - tStep);
Vector3 topTangent = Vector3.Normalize(topPosition - topPositionPrev);
Polygon polygon = MakePolygon();
for (int slice = 0; slice < sliceCount; ++slice)
{
int stack = stackCount;
Corner corner = polygon.MakeCorner(
points[(stack * (sliceCount)) + slice]
);
cornerNormals[corner] = topTangent;
}
}
}
