Spline

R2026b

Cubic interpolating plane curve or space curve

• 

Spline block

To add a block to a model, double-click the canvas and start typing the block name. Then, select the block from the list.

Libraries:
Simscape / Multibody / Curves and Surfaces

Description

This Spline block creates a continuous spline curve based on cubic interpolation between the specified points. The curve can be two dimensional, such as a planar cam profile, or three dimensional, such as a roller coaster track. The dimension of the spline depends on the dimension of the coordinate matrix. An N-by-2 matrix specifies a 2-D curve in the xy plane. An N-by-3 matrix specifies a 3-D curve. All the coordinates are resolved in the local reference frame of the block. Moreover, according to the specified end conditions, the curve can be either open or closed.

Examples

Using the Point-On-Curve Block: Flapping Wing Mechanism

This model simulates a barrel cam based wing flapping mechanism. This is a one degree of freedom mechanism and the two wings flap in sync with each other. The Spline and Point On Curve blocks have been used to model the Barrel Cam mechanism that actuates the flapping motion of the wings.

• Open Model

Ports

Frame

R — Reference frame

frame

Spline curve reference frame. Connect this frame port to another block to specify the location and orientation of the spline curve in a model.

Geometry

G — Spline curve representation

geometry

Geometry data associated with the representation of a 2-D or 3-D continuous spline curve. It provides the spline curve specification to other blocks to which it connects, such as the Point on Curve Constraint block.

Parameters

Interpolation Points — Coordinates of interpolation points for specifying spline curve

[6 -2 9; -6 5 -4; -6 -7 9; 6 0 -4; -3 6 9; -3 -8 -4] m (default) | N-by-2 matrix | N-by-3 matrix

Matrix that includes the coordinates of the interpolation points for defining the spline curve. Use an N-by-2 matrix to specify a 2-D spline and an N-by-2 matrix to specify a 3-D spline. Each row of the matrix specifies the Cartesian coordinates of an interpolation point with respect to the reference frame of the Spline block. An error occurs if the matrix has any repeated rows.

Tips

You can use the unique function to remove repeated rows from an input matrix.

End Conditions — Treatment of the curve endpoints

Periodic (Closed) (default) | Natural (Open)

End conditions of the spline curve. The Periodic (Closed) end conditions correspond to a closed curve. For this condition, the block joins the first and last data points with a continuous curve. The Natural (Open) end condition corresponds to an open curve.

The spline curve is a piecewise function of third-order polynomial segments connected end-to-end. The curve is built such that adjacent polynomial segments have the same first and second derivatives at the shared endpoints.

Graphic

Type — Spline visualization setting

From Geometry (default) | Marker | None

Visualization setting for this spline. Use the default setting, From Geometry, to show the spline. Select Marker to show a graphic marker such as a sphere or frame. Select None to disable visualization for this spline.

Visual Properties — Parameterizations for color and opacity

Simple (default) | Advanced

Parameterizations for specifying visual properties. Select Simple to specify Diffuse Color and Opacity. Select Advanced to specify more visual properties, such as Specular Color, Ambient Color, Emissive Color, and Shininess.

Dependencies

To enable this parameter, set Type to From Geometry or Marker.

Diffuse Color — True color as [R,G,B,A]

[0.0 0.0 0.0] (default) | three-element vector | four-element vector

True color under direct white light, specified as an [R,G,B] or [R,G,B,A] vector on a 0–1 scale. An optional fourth element specifies the color opacity on a scale of 0–1. Omitting the opacity element is equivalent to specifying a value of 1.

Dependencies

To enable this parameter, set Type to From Geometry or Marker.

Opacity — Graphic opacity

1.0 (default) | scalar in the range of 0 to 1

Graphic opacity, specified as a scalar in the range of 0 to 1. A scalar of 0 corresponds to completely transparent, and a scalar of 1 corresponds to completely opaque.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker.

2. Visual Properties to Simple.

Specular Color — Color of light due to specular reflection

[0.5 0.5 0.5 1.0] (default) | 3-by-1 or 1-by-3 vector with values in the range of 0 to 1 | 4-by-1 or 1-by-4 vector with values in the range of 0 to 1

Color of the light due to specular reflection, specified as an [R,G,B] or [R,G,B,A] vector with values in the range of 0 to 1. The vector can be a row or column vector. The optional fourth element specifies the color opacity. Omitting the opacity element is equivalent to specifying a value of 1. This parameter changes the color of the specular highlight, which is the bright spot on the rendered solid due to the reflection of the light from the light source.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker.

2. Visual Properties to Advanced.

Ambient Color — Color of ambient light

[0.15 0.15 0.15 1.0] (default) | 3-by-1 or 1-by-3 vector with values in the range of 0 to 1 | 4-by-1 or 1-by-4 vector with values in the range of 0 to 1

Color of the ambient light, specified as an [R,G,B] or [R,G,B,A] vector with values in the range of 0 to 1. The vector can be a row or column vector. The optional fourth element specifies the color opacity. Omitting the opacity element is equivalent to specifying a value of 1.

Ambient light refers to a general level of illumination that does not come directly from a light source. The Ambient light consists of light that has been reflected and re-reflected so many times that it is no longer coming from any particular direction. You can adjust this parameter to change the shadow color of the rendered solid.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker.

2. Visual Properties to Advanced.

Emissive Color — Self-illumination color

[0.0 0.0 0.0 1.0] (default) | 3-by-1 or 1-by-3 vector with values in the range of 0 to 1

Color due to self illumination, specified as an [R,G,B] or [R,G,B,A] vector in the range of 0 to 1. The vector can be a row or column vector. The optional fourth element specifies the color opacity. Omitting the opacity element is equivalent to specifying a value of 1.

The emission color is color that does not come from any external source, and therefore seems to be emitted by the solid itself. When a solid has an emissive color, the solid can be seen even if there is no external light source.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker.

2. Visual Properties to Advanced.

Shininess — Highlight sharpness

75 (default) | scalar with value constrained to 0–128

Sharpness of specular light reflections, specified as a scalar number on a 0–128 scale. Increase the shininess value for smaller but sharper highlights. Decrease the value for larger but smoother highlights.

Dependencies

To enable this parameter, set:

1. Type to From Geometry or Marker.

2. Visual Properties to Advanced.

Shape — Shape of graphic marker

Sphere (default) | Cube | Frame

Geometrical shape of the graphic marker. The Multibody Explorer shows the marker using the selected shape.

Dependencies

To enable this parameter, set Type to Marker.

Size — Width of the marker in pixels

10 pixels (default) | scalar

Width of the marker in pixels. This width does not scale with zoom level. Note that the apparent size of the marker depends partly on screen resolution, with higher resolutions packing more pixels per unit length, and therefore producing smaller icons.

Dependencies

To enable this parameter, set Type to Marker.

Programmatic Use: Add Block

To add the block programmatically, use the add_block function with one of these library block paths as the source.

"sm_lib/Curves and Surfaces/Spline"

Example: add_block("sm_lib/Curves and Surfaces/Spline","myModel/myBlock",MakeNameUnique="on")

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2015b