rotate

Rotate geometry

Syntax

rotate(g,theta)

rotate(g,theta,refpoint)

rotate(g,theta,refpoint1,refpoint2)

h = rotate(g,___)

Description

rotate(g,theta) rotates the geometry g about the z-axis by the angle theta, specified in degrees. Rotation follows the right-hand rule: a positive angle theta rotates counterclockwise, while sighting along the z-axis toward the origin.

rotate(g,theta,refpoint) uses the rotation axis specified by the reference point refpoint. The axis of rotation is the line in the z-direction passing through the reference point.

rotate(g,theta,refpoint1,refpoint2) uses the rotation axis specified by two reference points. This syntax is only valid for a 3-D geometry.

h = rotate(g,___) returns a handle h to the resulting geometry object g. Use this syntax with any input arguments from the previous syntaxes.

If the original geometry is a DiscreteGeometry object, then the function modifies the original geometry and returns the handle h to the modified DiscreteGeometry geometry object. If the original geometry is an AnalyticGeometry object, then h is a handle to a new DiscreteGeometry geometry object. In this case, the original geometry remains unchanged.

Examples

Rotate 2-D Geometry

Rotate a geometry with and without specifying the reference point for the axis of rotation.

Create a model.

model = createpde;

Import and plot a geometry.

g = importGeometry(model,"PlateHolePlanar.stl");
pdegplot(g)

Mesh the geometry and plot the mesh.

generateMesh(model);

figure
pdemesh(model)

Rotate the geometry around the default z-axis by 45 degrees. Plot the result.

rotate(g,45);

figure
pdegplot(g)

Plot the geometry and mesh. The rotate function modifies a geometry, but it does not modify a mesh.

figure
pdegplot(g)
hold on
pdemesh(model)

After modifying the geometry, always regenerate the mesh.

generateMesh(model);

figure
pdegplot(g)
hold on
pdemesh(model)

Restore the original geometry position.

rotate(g,-45);

Rotate the geometry by the same angle, but this time use the center of the geometry as a reference point. The axis of rotation is the line in the z-direction passing through the reference point.

rotate(g,45,[5 10]);

Regenerate the mesh.

generateMesh(model);

Plot the resulting geometry and mesh.

figure
subplot(1,2,1)
pdegplot(model)
axis([-6 16 -1 21])
subplot(1,2,2)
pdemesh(model)
axis([-6 16 -1 21])

Rotate 3-D Geometry

Rotate a geometry with and without specifying the reference points for the axis of rotation.

Create and plot a geometry.

g = multicuboid(1,5,1);
pdegplot(g)

Rotate a 3-D geometry around the default z-axis by 45 degrees. Plot the result.

rotate(g,45);
pdegplot(g)

Restore the original geometry position.

rotate(g,-45);
pdegplot(g)

Rotate the geometry by the same angle, but this time around the y-axis.

rotate(g,45,[0 0 0],[0 1 0]);
pdegplot(g)

Input Arguments

g — Geometry

DiscreteGeometry object | AnalyticGeometry object

Geometry, specified as a DiscreteGeometry or AnalyticGeometry object.

Example: g = model.Geometry

theta — Rotation angle in degrees

real number

Rotation angle in degrees, specified as a real number.

Example: rotate(g,90)

refpoint — Reference point for rotation axis

vector of two or three real numbers

Reference point for a rotation axis, specified as a vector of two or three real numbers. The axis of rotation is the line in the z-direction passing through the reference point.

Example: rotate(g,45,[1 1.5])

refpoint1,refpoint2 — Reference points that define rotation axis

vector of three real numbers

Reference points that define a rotation axis for a 3-D geometry, specified as a vector of three real numbers.

Example: rotate(g,45,[0 0 0],[1 1 1])

Output Arguments

h — Resulting geometry

handle

Resulting geometry, returned as a handle. If the original geometry g is a DiscreteGeometry object, then h is a handle to the modified DiscreteGeometry geometry object g. If g is an AnalyticGeometry object, then h is a handle to a new DiscreteGeometry geometry object. In this case, the original geometry g remains unchanged.

Tips

• rotate modifies a geometry, but it does not modify a mesh. After modifying a geometry, regenerate the mesh to ensure a proper mesh association with the new geometry.

• If g is an AnalyticGeometry object, and you want to replace it with the resulting discrete geometry, assign the output to the original geometry, for example, g = rotate(g,90).

Version History

Introduced in R2020a

R2021a: Geometry transformation for analytic geometries

rotate now works with AnalyticGeometry objects.