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## 3.117. symmetric command

Description: This command creates an object that is symmetric to the original one with respect to a plane of symmetry.

Inline mode usage:

• symmetric -h: Displays the help file that summarizes the parameters for this command.
• symmetric –all –p <x1 y1 z1> <x2 y2 z2>: Get symmetric objects (all) moving from start point to end point.
• symmetric –s <name> –p <x1 y1 z1> <x2 y2 z2>: Get symmetric object (<name> object) moving from start point to end point.
• symmetric –c -all –p <x1 y1 z1> <x2 y2 z2>: Get symmetric objects (all) copying from start point to end point.
• symmetric –c -s <name> –p <x1 y1 z1> <x2 y2 z2>: Get symmetric object (<name object) copying from start point to end point.

Interactive mode usage:

• Invocation: symmetric, symmetric -c, symmetric -all or symmetric -c -all.
• Remark: When using the -c parameter, the original object is kept in the geometry. Otherwise, the original object will be deleted.
• Parameters:
• Original objects (when not using the all parameter) can be selected by clicking on them in the geometry view (hold Ctrl for multiple selection) or in the tree view.
• First point of normal vector for the plane of symmetry.
• Second point of normal vector for the plane of symmetry.

Example:

We are going to create a cylinder-like surface by using the example surface created for the surface command as a base. First, let’s create the surface:

>surface

Points in u direction : 2

Points in v direction : 3

Point  [x y z w]: 0 2 3 1

Point  [x y z w]: 2 2 3 0.7

Point  [x y z w]: 2 0 3 1

Point  [x y z w]: 0 2 0 1

Point  [x y z w]: 2 2 0 0.7

Point  [x y z w]: 2 0 0 1

This surface is only the fourth part of our desired cylindrical surface. Now we are going to create a symmetric surface using the YZ plane as a plane of symmetry. We want to keep the original surface, so we must use the -c parameter:

>symmetric -c

Select objects on screen (Press enter when done): // Select the surface

First point (for normal vector of symmetry plane) [x y z]: 0 0 0

Second point (for normal vector of symmetry plane) [x y z]: 1 0 0 Half cylindrical shape

The only thing left to do to obtain the desired shape is to create the symmetric shape using the existing surfaces, with the XZ plane defined as a plane of symmetry. For convenience, we will use the all parameter this time.

>symmetric -c all

First point (for normal vector of symmetry plane) [x y z]: 0 0 0

Second point (for normal vector of symmetry plane) [x y z]: 0 1 0

> Cylindrical shape

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