Interface IExtrudeShape

Implement this class to create a customized shape that can be extruded along a Spline using the SplineMesh class.

Some default shape implementations are available in the UnityEngine.Splines.ExtrusionShapes namespace.

SplineMesh generates extruded mesh geometry in the following manner (pseudo-code):

extrudeShape.Setup(spline, numberOfSegments);
for(int i = 0; i < numberOfSegments; ++i)
{
    float t = i / (numberOfSegments - 1);
    extrudeShape.SetSegment(i, t, splinePositionAtT, splineTangentAtT, splineUpAtT);
    for(int n = 0; n < extrudeShape.SideCount; ++n)
        vertices.Add(extrudeShape.GetPosition(n / (extrudeShape.SideCount - 1), n));
}

This example IExtrudeShape implementation creates a tube.

Namespace: UnityEngine.Splines

Assembly: Unity.Splines.dll

Syntax

public interface IExtrudeShape

Examples

// While not strictly necessary, marking the class as Serializable means that
// this can be edited in the Inspector.
[Serializable]
public class Circle : IExtrudeShape
{
    [SerializeField, Min(2)]
    int m_Sides = 8;

    float m_Rads;

    // We only need to calculate the radians step once, so do it in the Setup method.
    public void Setup(ISpline path, int segmentCount)
    {
        m_Rads = math.radians(360f / SideCount);
    }

    public float2 GetPosition(float t, int index)
    {
        return new float2(math.cos(index * m_Rads), math.sin(index * m_Rads));
    }

    public int SideCount
    {
        get => m_Sides;
        set => m_Sides = value;
    }
}

Properties

SideCount

How many vertices make up a single ring around the mesh.

Declaration

int SideCount { get; }

Property Value

Type	Description
int	How many vertices make up a revolution for each segment of the extruded mesh.

Methods

GetPosition(float, int)

This method is responsible for returning a 2D position of the template shape for each vertex of a single ring around the extruded mesh. Note that both interpolation t and index are provided as a convenience.

Declaration

float2 GetPosition(float t, int index)

Parameters

Type	Name	Description
float	t	The normalized interpolation [0...1] for a vertex around an extruded ring.
int	index	The index of the vertex in the extruded ring.

Returns

Type	Description
float2	A 2D position interpolated along a template shape to be extruded. This value will be converted to a 3D point and rotated to align with the spline at the current segment index.

SetSegment(int, float, float3, float3, float3)

Implement this function to access information about the spline path being extruded for each segment. SplineMesh invokes this method once before each ring of vertices is calculated.

Declaration

void SetSegment(int index, float t, float3 position, float3 tangent, float3 up)

Parameters

Type	Name	Description
int	index	The segment index for the current vertex ring.
float	t	The normalized interpolation ratio corresponding to the segment index. Equivalent to index divided by segmentCount - 1.
float3	position	The position on the Spline path being extruded along at t.
float3	tangent	The tangent on the Spline path being extruded along at t.
float3	up	The up vector on the Spline path being extruded along at t.

Setup(ISpline, int)

Implement this function to access information about the ISpline path being extruded and number of segments. SplineMesh invokes this method once prior to extruding the mesh.

Declaration

void Setup(ISpline path, int segmentCount)

Parameters

Type	Name	Description
ISpline	path	The ISpline that this template is being extruded along.
int	segmentCount	The total number of segments to be created on the extruded mesh. This is equivalent to the number of vertex "rings" that make up the mesh positions.