/// <summary>
/// Extrudes the cross section along the curve.
/// </summary>
/// <param name="curve">The curve to extrude along.</param>
/// <param name="crossSection">The cross section of the extrusion.</param>
/// <param name="distanceCounter">A counter for customizing longitudinal texture coordinates.</param>
/// <returns>A structure containing the result.</returns>
public static ExtruderResult Extrude(Curve curve, CrossSection2D crossSection, ref float distanceCounter, LineTextureMode textureMode = LineTextureMode.Tile)
{
// Calculate counting parameters
int sliceCount = curve.Count;
int segmentCount = sliceCount - 1;
int vertexCount = crossSection.vertexCount * sliceCount;
int triangleCount = 2 * crossSection.edgeCount * segmentCount;
int triangleIndexCount = 3 * triangleCount;
// Declare storage
List <Vector3> vertices = new List <Vector3>(vertexCount);
List <Vector3> normals = new List <Vector3>(vertexCount);
List <Vector4> tangents = new List <Vector4>(vertexCount);
List <Vector2> uv = new List <Vector2>(vertexCount);
List <int> triangles = new List <int>(triangleIndexCount);
// Compute spatial vectors
foreach (OrientedPoint orientedPoint in curve)
{
// Add per-slice vertices
foreach (Vector3 vertex in crossSection.vertices)
{
vertices.Add(orientedPoint.TransformPoint(vertex));
}
// Add per-slice normals
foreach (Vector3 normal in crossSection.normals)
{
normals.Add(orientedPoint.TransformDirection(normal));
}
// Add per-slice tangents
Vector3 tangent = orientedPoint.TransformDirection(Vector3.forward);
for (int i = 0; i < crossSection.vertexCount; i++)
{
tangents.Add(tangent);
}
}
// Compute texture vectors
for (int i = 0; i < curve.Count; i++)
{
distanceCounter += curve.deltas[i];
// Add per-slice uvs
foreach (Vector2 crossSectionUV in crossSection.uv)
{
float u, v;
switch (textureMode)
{
case LineTextureMode.Stretch:
u = curve.distances[i] / curve.Length;
break;
case LineTextureMode.DistributePerSegment:
u = (float)i / curve.Count;
break;
case LineTextureMode.RepeatPerSegment:
u = i;
break;
default:
u = distanceCounter;
break;
}
v = crossSectionUV.y;
Vector2 texCoord = new Vector2(u, v);
uv.Add(texCoord);
}
}
// Compute triangle indices
for (int i = 0, baseIndex = 0; i < segmentCount; i++, baseIndex += crossSection.vertexCount)
{
// Add per-segment triangles (triangle indices)
foreach (Vector2Int edge in crossSection.edges)
{
int a = baseIndex + edge.x;
int b = baseIndex + edge.y;
int c = baseIndex + edge.x + crossSection.vertexCount;
int d = baseIndex + edge.y + crossSection.vertexCount;
triangles.Add(a);
triangles.Add(b);
triangles.Add(d);
triangles.Add(a);
triangles.Add(d);
triangles.Add(c);
}
}
return(new ExtruderResult(
vertices,
normals,
tangents,
uv,
triangles
));
}
/// <summary>
/// Extrudes the cross section along the curve.
/// </summary>
/// <param name="curve">The curve to extrude along.</param>
/// <param name="crossSection">The cross section of the extrusion.</param>
/// <returns>A structure containing the result.</returns>
public static ExtruderResult Extrude(Curve curve, CrossSection2D crossSection, LineTextureMode textureMode = LineTextureMode.Tile)
{
float distanceCounter = 0.0f;
return(Extrude(curve, crossSection, ref distanceCounter, textureMode));
}