Engineering Solutions

Symmetry panel

Symmetry panel

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Symmetry panel

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The Symmetry panel allows you to create symmetries that influence handles, morph volumes, domains, blocks, rwalls, and shapes.

 

Panel Usage

The Symmetry panel has two subpanels: create and update by domain.

symmetry_panel

Changes made on one subpanel do not affect the other, and are persistent so that you can switch freely between subpanels without losing any settings already made.

There are two basic symmetry groups: reflective and non-reflective.

hmtoggle_arrow1Reflective Symmetries

Reflective symmetries are 1-plane, 2-plane, 3-plane, and cyclical. You can use reflective symmetries to link handles in a symmetric fashion so that the movements of one handle will be reflected and applied to the symmetric handles. You can also use reflective symmetries to reflect morphs performed on domains when using the alter dimensions: radius, curvature, and arc angle tools or any map to geom operation. To turn the reflection of morphing operations off, clear the symlinks check box or inactivate the symmetry in the Morph Options panel.

Reflective symmetries can be defined as either unilateral or multilateral and either approximate or enforced.

•Unilateral symmetries have one and only one side that governs the others, but not vice versa.  For example, handles created and morphs applied to handles on the positive side of the symmetry are reflected onto the other side or sides of the symmetry, but handles created or morphs applied to handles on the other side or sides of the symmetry are not reflected.
•For multilateral symmetries, all sides govern all other sides.  For example, a handle created or a morph applied to a handle on any side is reflected to all the other sides.
•Approximate symmetries may contain handles that are not symmetric to other handles.  For example, handles created on any side of the symmetry are not reflected to the other sides. This option is best for asymmetrical, but similar, domains or for a cyclical symmetry applied to a mesh that sweeps through an arc but not a full circle.
•Enforced symmetries cannot contain handles that are not symmetric on all other sides.  For example, handles created or deleted on any side of the symmetry are created or deleted on the other sides so that the symmetry is maintained.  When a reflective symmetry is created with the enforced option, additional handles may also be created to meet the enforcement requirements.
Note:Handles created due to the enforced option may not be located on any mesh, however, they will always be assigned to the nearest domain and will affect nodes in that domain.

Reflective symmetries

One plane

A mirror is placed at the origin perpendicular to the selected axis (default = x-axis).

Two plane

Two mirrors are placed at the origin perpendicular to the selected axis and the subsequent axis (that is x and y, y and z, z and x) (default = x and y-axis).

Three plane

Three mirrors are placed at the origin perpendicular to all three axes.

Cyclical

Two mirrors are placed along the selected axis (default = z-axis) and running through the origin with a given angle in between that is a factor of 360. The result is a wedge that is reflected a certain number of times about the selected axis.

 
hmtoggle_arrow1Non-Reflective Symmetries

Non-reflective symmetries are linear, circular, planar, radial 2-D, cylindrical, radial + linear, radial 3-D, and spherical.  These change the way that handles influence nodes as well as link the symmetric handles so that the movement of one affects the others.  You can control whether or not a handle perturbation is applied to symmetric handles for both reflective and non-reflective symmetries by checking or unchecking symlinks or making the symmetries active or inactive in the Morph Options panel. However, the unique handle to node influences for non-reflective symmetries can only be turned off by making the symmetry inactive.

Generally speaking, the handles for a domain with non-reflective symmetry will act as if they are the shape of the symmetry type.  For instance, a domain with linear symmetry causes handle movements to act on the domain as if the handle was a line in the direction of the x-axis.  A domain with circular symmetry causes handle movements to act on the domain as if the handle was a circle centered around the z-axis.  The edges of a domain affect how influences between handles and nodes are calculated.  Non-reflective symmetries work best for domains that are shaped like the symmetry type and have a regular mesh.  For example, a circular symmetry works best for a round domain with a concentric mesh.

Non-reflective symmetries

Linear

Handle acts as a line drawn through the handle location parallel to the selected axis (default = x-axis).

Circular

Handle acts as a circle drawn through the handle position about the selected axis (default = z-axis).

Planar

Handle acts as a plane drawn through the handle location perpendicular to the selected axis (default = x-axis).

Radial 2-D

Handle acts as a ray drawn through the handle position originating from and extending perpendicular to the selected axis (default = z-axis).

Cylindrical

Handle acts as a cylinder drawn through the handle position about the selected axis (default = z-axis).

Radial + linear

Handle acts as a plane drawn through the handle position extending from the selected axis (default = z-axis).

Radial 3-D

Handle acts as a ray drawn through the handle position originating from origin.

Spherical

Handle acts as a sphere drawn through the handle position centered on the origin.

 

Symmetries can be combined, but you must be careful not to create confusing symmetrical arrangements.  Symmetries can also be applied to unconnected domains.  In this case, the symmetric handle linking works the same as that for connected domains, but the influences between handles and nodes for non-reflective symmetries do not extend across to all domains.

 

Subpanels and Inputs

The Symmetry panel contains the following subpanels and command buttons:

hmtoggle_arrow1Create

Use the Create subpanel to create new symmetries, to assign them to domains, and to update existing symmetries.

 

Panel Inputs

Input

Description

name =

Type in a name for the new symmetry that you wish to create.  Alternatively, click the button twice to pick from a list of existing domains that you wish to update, change the other settings as desired, and then click the update button to save the changes.

domains

Use this entity selector to pick the domain or domains that the new symmetry is part of.

morph volumes & mapping

By default, symmetries do not affect morph volumes or map to geom operations. If you wish the symmetry to affect morph volumes and mapping operations as well as domains, select this check box. Symmetries that affect morph volumes will affect all of the morph volumes in the model. Symmetries that affect mapping operations will affect all mapping operations, even if there are no domains in the model.

approximate / enforced

For reflective symmetries (1-, 2-, or 3-plane, or cyclical), choose how strict the symmetric requirements should be:

•Approximate symmetries may contain handles that are not symmetric to other handles.  For example, handles created on any side of the symmetry are not reflected to the other sides. This option is best for asymmetrical, but similar, domains or for a cyclical symmetry applied to a mesh that sweeps through an arc but not a full circle.
•Enforced symmetries cannot contain handles that are not symmetric on all other sides.  For example, handles created or deleted on any side of the symmetry are created or deleted on the other sides so that the symmetry is maintained.  When a reflective symmetry is created with the enforced option, additional handles may also be created to meet the enforcement requirements.
Note:Handles created due to the enforced option may not be located on any mesh, however, they will always be assigned to the nearest domain and will affect nodes in that domain.

(symmetry type switch)

Use this switch to pick the type of symmetry you wish to create: One plane, Two plane, Three plane, Cyclical, Linear, Circular, Planar, Radial 2-D, Cylindrical, Radial + linear, Radial 3-D, Spherical.

multilateral / unilateral

For reflective symmetries (1-, 2-, or 3-plane, or cyclical), choose how different sides of the symmetry interact with each other:

•Unilateral symmetries have one and only one side that governs the others, but not vice versa.  For example, handles created and morphs applied to handles on the positive side of the symmetry are reflected onto the other side or sides of the symmetry, but handles created or morphs applied to handles on the other side or sides of the symmetry are not reflected.
•For multilateral symmetries, all sides govern all other sides.  For example, a handle created or a morph applied to a handle on any side is reflected to all the other sides.

syst

Select a coordinate system with which the symmetry is aligned.

align with:

Define which axis of the chosen system the symmetry is aligned with: thedefault axis, or one of its x/y/z axes.

size =

Type in a size for the symmetry’s visual icon.  This does not affect the symmetry’s performance--only the appearance of the symmetry icon in the graphics area.

color

Click this button to pick a color for the symmetry's icon which displays in the graphics area.

 
hmtoggle_arrow1Update by Domain

Use the Update by Domain subpanel to change which symmetries are attached to a specific domain.

 

Panel Inputs

Input

Description

domain

Use this selector to pick the desired domain. Only one domain can be selected at a time.

symmetries

Use this selector to pick the symmetries that you wish to assign to the currently selected domain. You may pick multiple symmetries.

 
hmtoggle_arrow1Command Buttons

The following action buttons appear throughout the subpanels:

Button

Action

create

Creates a new symmetry based on the settings you have specified in the create subpanel.

update

When an existing symmetry is specified in the name = field, clicking this button updates the symmetry to use the settings currently specified in the create subpanel.

review

On the create subpanel, this displays the symmetry links between the handles for the selected symmetry.

On the update by domain subpanel, review loads the symmetries associated with the selected domain into the symmetry collector.

refresh

Updates the symmetry links between handles.

Note:This may cause different handles to be linked and new handles to be created if the model was morphed while the symmetries were inactive or if symlinks was turned off.

reject

Reject undoes the creation of an entity (such as a shape or constraint).  This differs from undo because undo only undoes the movement of nodes; rejecting an entity can also undo node movements, but its primary function is to delete an entity that was just created.

return

Exits the panel.

 

 

See Also:

Changing a Curvature Using Map to Geometry - HM-3530

HyperMorph Module

HyperMorph Strategies