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Using the Geometry Editor

Overview

Geometry Editor Tools

Restrictions On Using Component Transform Tools

Using Shape Transform Tools

Tutorial - Space Capsule

Tutorial - Creating a Crater

Tutorial - Creating a Pool Table

Overview

The Geometry Editor (Figure 9) is used to create and edit instances of CcVertexGeometry. The editor saves CcVertexGeometry instances as binary files (extension ".geo") located within the ST3D geometry folder hierarchy. The layout and operation of the Geometry Editor is similar to the Part Editor’s. The primary differences between the Geometry Editor and the Part Editor are the types of tools provided and the types of aspects that can be edited. The Geometry Editor can be opened using menu item "Tools->ST3D->Geometry Editor" or by double clicking on the "Geometry Editor" icon located in Dolphin’s "ST3D" subfolder.

Like the Part Editor, the Geometry Editor includes a perspective view and a card container. The card container in the Geometry Editor includes "Scene", "Geometry" and "Tool" pages.

Multiple geometry objects can be added to the perspective view but only the first (as shown in the node browser on the "Scene" page) is actually saved to the geometry file. If multiple geometry objects are present in the perspective view, they should be combined into a single geometry object using the editor’s "Combine geometry" option prior to saving.

Figure 9. The Geometry Editor

The "Geometry" page shows subfolders within the ST3D Geometry folder and the geometry files present in the currently selected folder. The "preview view" below the geometry chooser shows the currently selected geometry file. The selected geometry object can be added to the perspective view by double clicking on the file name in the file view.

The node browser on the "Scene" page displays the nodes and components (faces and vertices) currently being edited and provides an alternate means of selecting and deselecting shapes and components via its popup menu.

The "aspect inspector" on the "Scene" page displays the published aspects of the element currently selected in the node browser. The geometry editor only allows the name of a face or vertex to be edited.

Geometry Editor Tools

The Geometry Editor provides a number of tools for editing a geometry object. The list of tools is displayed by invoking the popup menu in the perspective view. A list of available tools and their descriptions is provided below.

Translate component - world – Moves selected components in direction indicated by axis handle. World position of first selected component can be specified using the tool parameter view.
Translate component - normal – Moves selected components along their normal direction. World position of first component can be specified using the tool parameter view.
Translate user defined – Move selected components along the current user defined direction
Set UDD from normal – Sets the current user defined direction (UDD) from the normal of the currently selected component.
Set UDD from edge – Sets the current user defined direction from the vector derived from a selected edge.
Extrude face (remove original) – Creates a copy of the currently selected face and "attaches" the copy to the original face’s vertices using n faces where n is the number of vertices in the original face. The original face is removed from the geometry object.
Extrude face (keep original) – Same as above but original face is retained.
Inset face – Same as "Extrude face (remove original)" but copied face is inset from the original face’s dimension.
Detach face – Detaches the selected face and its vertices from the other components in its geometry.
Reverse faces – Reverses the ordering of the selected faces vertices. This causes the visible side of the face to toggled when face culling is in #hideFront or #hideBack mode (See Part Editor discussion).
Remove faces – Deletes the selected faces.
Combine vertices – With n vertices selected, all references to vertices 1 through n / 2 are replaced with references to vertices (n / 2 + 1). n must be an even number.
Collapse face – Replaces a face and all of its vertices with a single vertex.
Create face from vertices – Creates new face using selected vertices.
Create edge – Creates a new edge within a face. Requires one face and two edges within that face to be selected.
Combine geometry – Combines the geometry contained in two or more selected shapes into a single shape/geometry.
Segment face – Segments a quad (four-sided face) into multiple triangles.

Restrictions When Using Component Transform Tools

Certain restrictions must be observed when manipulating the components of a geometry object. An object’s appearance may be severely distorted if these restrictions are not met.

The first restriction is that all faces in a geometry object must be convex (like a stop sign). An easy way to violate this restriction is to select a single vertex in a cube and translate it in any direction.

The second restriction is that all vertices of a face must lie in the same plane. This restriction can also be violated by moving an individual vertex in a cube.

(Support for polygon tessellation in future versions of ST3D may lessen or eliminate these restrictions).

Using Shape Transform Tools

The shape transform tools available in the Geometry Editor are identical to those found in the Part Editor. Shapes transformed using these tools will be colored red and should have their vertex positions recalculated prior to 1) using a component transform tool and/or 2) saving the geometry object. This is accomplished using menu item "Set new vertex positions" in the "Shape operations" submenu.

Tutorial – Creating a Space Capsule

Let’s build a model that might serve as a rough representation of a Mercury space capsule (See Figure 10).

Open the Geometry Editor (Menu item "Tools->Additional Tools->CC Geometry Editor").

Add an instance of ‘Geometry -> CC 3D Shapes -> "column12.geo" to the view. Select the column’s "top" face. Select the "Scale face" tool and adjust the face’s size by clicking and dragging on the blue arrow of the axis handle. Shrink the face so that its diameter is roughly half of its original size.

With the top face still selected, execute "Extrude face (remove original). Again, select the top face. Now select the "Translate world" tool and move the extruded face (blue arrow) until its z coordinate (as indicated in the tool parameter view) is approximately 1.25. Shrink the face slightly using the "Scale face tool".

Clear all selections and then reselect the shape. Select "Watch selected". Move the viewpoint using CTRL+<Down arrow> until the bottom of the shape is visible. Select the bottom face and execute "Inset face". Select the inset face. Choose the "Translate world" tool and move the extruded face downwards slightly.

Execute "Extrude face (remove original)". Selected the extruded face and, using the "Translate world" tool, move the extruded face downward by approximately 0.15 units. Shrink the face slightly using the "Scale face" tool. The final shape should appear similar to the last frame in Figure 10.

Figure 10. Creating a Mercury space capsule

Tutorial – Creating a Crater

Open the Geometry Editor.

Add an instance of "unit_square.geo" located in Geometry->CC 2D Shapes.

Resize the square to 10 @ 10 @ 0 using the Resize tool (Shape operations submenu). With the shape still selected, invoke "Set new vertex positions" (Shape operations submenu).

Select the shape’s only face (should be outlined in red when selected). Invoke "Segment face" and specify 7 @ 7 divisions when prompted. The face is segmented into triangles.

Select edges as shown in Figure 11a. Select the "Translate world" tool and move the edges along the z-axis (blue arrow on axis handle) by approximately 0.5 units (as indicated in the tool parameter view).

Round out the perimeter of the shape by selecting individual edges and vertices and moving them within the xy plane (red and green arrows on the axis handle). Do the same for the crater’s rim. Remove corner faces. The finished crater should appear similar to the screen shot in Figure 11b.

Figure 11. a) Edges selected for rim of crater and b) Finished crater

Tutorial – Creating a Pool Table

A series of screen shots depicting the process of creating the pool table is shown in Figure 12.

Open the Geometry Editor.

Add an instance of "cube.geo" located in Geometry->CC 3D Shapes.

Using the "Tool" page, resize the box to 0.50 @ 4.00 @ 0.25. The box will now appear red. Move the viewpoint forward slightly so that the box occupies most of the view.

With the box still selected, invoke "Set new vertex positions" from the "Shape operations" submenu.

Select the right vertical edge of the face nearest the viewpoint. (If you’re unsure which edge to click on, use the node browser on the "Scene" page to select it instead. Expand the CcVertexShape in the node browser, then expand the "edges" entry. Select the entry labeled "QE #12", then choose "Select" in the node browser’s popup menu).

Select "Translate world" tool. Set the edge’s position to be 0.25 @ -2.50 @ 0.00.

Deselect the edge by clicking on it. The box should still be selected. Select "Copy" followed by "Paste". A new instance of the box is added to the scene and is selected.

Select the "Rotate part (local)" tool in the "Shape operations" submenu. Rotate the selected box about the "z" axis by –90 degrees.

Using the node browser, select vertex #4 in the new shape. Then select vertex #1 in the first shape. Invoke "Align components" from the perspective view’s "Shape operations" submenu.

Clear all selections and then select the second instance of CcVertexShape in the node browser. Invoke "Set new vertex" positions.

Using the node browser, select edge #9 in the second shape. Select "Translate world" tool and set the edge’s position, as indicated on the "Tool" page, to 0.25 @ 2.50 @ 0.00.

Using the node browser, select face #3 in the second CcVertexShape and face #4 in the first shape. Invoke "Separate components…" Do the same for face #4 in the second CcVertexShape. Now set the separation between the two faces to 0.5 units using "Separate components…" on the perspective view’s "Shape transforms" submenu.

Clear selections and then select the second shape. Execute "Set new vertex positions".

Perform a second paste operation (previous shape is still in the clipboard). A third shape is added to the view and selected. Choose the rotate (local) tool and, with the "Tool" page selected, rotate the shape about the z-axis by 180 degrees and then rotate it about the y-axis by 180 degrees.

Select face #3 in the third shape and face #3 in the first shape. Set the separation between the two faces to 0.5 units using "Separate components…". "Set new vertex positions" on the third shape.

Select all three shapes and invoke the "Combine geometry" operation. The view and node browser should now contain a single vertex shape that appears similar to the first frame in Figure 12.

Select vertices 7, 14, 13 and 8 (order is important). Execute "Create face from vertices". A new face is created in the gap between the two table segments.

Select the newly created face and execute "Inset face". A new, smaller face, appears in the middle of the selected face (see second frame of Figure 12).

Clear selections and then select the inner face created in the previous step. Select the "Translate world" tool and set the z coordinate of the face’s position to –0.5. The "pocket" should look similar to the third frame of Figure 12.

Create a back face for the pocket by selecting vertices 7, 14, 10 and 3 (again, order is important). Don’t worry about being able to see through certain faces. In the Geometry Editor, only one side of a given face is rendered at a time. The shape can be easily configured later (in the Part Editor) to have both sides visible (solid).

Repeat the pocket creation process for the "side pocket" gap. Vertex indices for the bottom pocket face are 15, 19, 20 and 16.

Select the shape and perform a copy and paste. The pasted shape (second shape) is now selected. Rotate it about the z-axis by 180 degrees.

Select face #16 in the second shape and face #4 in the first shape. Execute "Separate component…" with a distance of 0.5.

"Set new vertex positions" on the second shape. Then select both shapes and combine them ("Combine geometry"). Add the corner pockets to the two remaining gaps in the table.

Select the following vertices: 8, 13, 17, 37 40, 45, 49, 5. Execute "Create face from vertices". The finished table should look like the final frame in Figure 12.

The table can be saved using "File->Save As…".

Figure 12. Creating the pool table