What happened to my move widget? Why can't I select any objects in Blender?

 Is the move widget on your shape in Blender partially or completely missing?

In the above image, notice that the move widget on the selected shape has only one arrow instead of 3 allowing movement only in that direction.  Look to the right of the selected shape in the Location section of the panel, and notice that the y and z locations are locked.  That keeps you from accidentally moving it in the 3d View.  If you clock on the locks, those directions will be unlocked and the other two arrows on the move widget will return

Sometimes the SimuSEM extension will lock one or more axes in location and/or rotation on a particular shape by default, if it is likely that it should not be moved.  For instance, the location of the substrate layers are locked in all 3 axes by default.  However, if you want to move a shape in a direction that is locked, you can either unlock it or type in a new location in that panel.  Or if you don't want to accidentally transform an object, you can lock the location, rotation and/or scale of any axis manually.

Why can't I select any objects?

If you are trying to select an object, but you can't, one likely cause is that you are in Edit Mode.  You need to be in Object mode to select an object.  Edit mode will allow you to select a part of an object, which is sometimes useful in SimuSEM.  Whenever you are asked to select a vertex, edge or face of an object,  you are in Edit Mode in Blender.  SimuSEM always has a Cancel button next to buttons that switch to Edit Mode, such as Choose a Pixel or Cursor to Face buttons.  However, you can always switch back to Object mode by click in the field circled in the above figure.  You can not add new shape in Edit Mode.

Fix Sample Rotation Pivot

 SimuSEM Tip:  Rotating Sample 

When using the rotation widget in the upper right corner, does the sample seem to rotate around a point far away from the center?  Fix, by telling Blender to use a selected object as the center of rotation.  First, select a small enough shape in the sample.  Then press the period key in the numpad on a PC keyboard.  Blender calls this Orbit Around Selection.

If you end up with a large shape as the rotation pivot and have trouble rotating the 3d view, just select a relatively small object and press the numpad (.) key.  Look here or in the Blender manual for more information.

Creating Custom Shapes

SimuSEM Tutorial:  Custom Shapes, Part 1

Several methods for creating custom shapes are available in SimuSEM, including:

• using primitive shapes and Boolean operations
• modifying planar shapes using Blender's editing tools

This tutorial will discuss using Blender's editing tools to modify planar shapes.  Any convex shape that is composed of only flat planes (what we will call a multiplane shape) in Blender will be represented correctly in a simulation.  In SimuSEM 3.0, the user is responsible for creating convex multiplane shapes.  This requirement is not a significant restriction since any multiplane shape can be split into 2 or more shapes that are convex.

Blender has many tools that can be used to edit shapes, and any can be used as long as final edited shapes are multiplane and convex.  This tutorial will describe some methods of editing shapes that we have found useful.

1.  Edit vertices, edges and faces directly in Edit Mode.

Start by selecting the shape you wish to edit and switching to Edit Mode.  The three boxes just to the right of the mode selection that appear when you are in Edit Mode allow you to select either vertices, edges or faces, respectively in the selected shape.  The selected vertex, edge or face can now be modified directly.

When you are done, make sure you switch back to object mode.  Many SimuSEM tools are not available in Edit Mode.

2.  Use a construction block and difference Boolean modifier

A block is a good shape to start with when creating a custom multiplane shape.  

Let's say that you want to create an a slanted top surface at a known angle, like this:

• First create the block that you will modify as well as a construction block, which is red in this example.
• Then rotate the red block to the desired angle. 

•  Make sure the scale of both objects are the same.  You can set the scale of all selected objects to 1 by pressing ctrl-a, s. (Hold down shift key to select more than one object).
• Next position the red block so that it overlaps the section of the sample that you want to remove.  The red block should be large enough to overlap the entire section to be removed.

• Next, select the block to be cut and click on the blue wrench in the Properties Panel to add a Boolean modifier.  

• In the Boolean modifier panel, choose Difference and the Object field should show the construction block.
• Then, make sure the red construction block is covering only the section to be removed, click on the down arrow at the top right of the Boolean panel and choose Apply.  Once you click on apply, the cut area can no longer be modified.
• Finally, delete the red block.

If you want the sloped surface to start a certain distance from the bottom of the shape, you can create another construction block that can be used to align the slanted block as shown here:

Warning:  Don’t make changes to any other modifiers as that may change how the geometry is described to the simulation.

Methods of accurately aligning shapes will be covered in other tutorials.

Sample Fades in the Distance

SimuSEM Tip:  How to fix a large sample fading into the distance

Let's say you want to create a very tall tower, like this one:

If you zoom out, the sample will fade in the distance.

To fix this problem, increase the clip end value in the view tab.  In this example, it was increased from 5,000 (SimuSEM's default) to 30,000.

Align Edge With Vertex

 SimuSEM Tutorial:  Align the edge of one shape with a vertex of another shape

This tutorial makes use of Blender’s Pie Menus and Edit Mode.  A Pie Menu is a menu in which the options are spread out in a circle around the mouse pointer.

Edit Mode in Blender allows you to select and/or edit parts of a shape.  In this tutorial, Edit Mode is used to select the edge of the shape that you want to align.  Use Edit mode carefully because you can easily deform a shape such that it will not simulate properly.  With some limitations, custom shapes can be created in Edit mode, but that is not the topic of this tutorial.

For this tutorial, we will align the center of the bottom edge of the purple block with a vertex on the turquoise block\

1. Switch to Edit mode, select the edge you want to align..
• Start by selecting the object that you want to move.(the purple block)
• Switch to Edit Mode
• Choose the middle button to the right of “Edit Mode” (as shown in the figure), which allows you to choose an edge.  Then click on the correct edge.  (The first button lets you choose a vertex and the third, a face.) 

2. Press Shift+S to open a pie menu and choose Cursor to Selected (bottom)

• If you want to align the object to a location on an edge that is not the middle or the end, subdivide the edge to get a vertex in the desired location before choosing Cursor to Selected.  Use Vertex --Subdivide in the top 3D View menu.  The subdivide menu will appear in the lower left corner of the 3D View, and it may be collapsed.
2. Switch back to Object Mode 
3. Right click on the object–Set Origin–Origin to 3d Cursor.  This sets the object’s origin to the edge that you want to align
4. Now move the 3d cursor to the vertex of the other shape
• Turn on Snap to Vertex in the top menu bar.
• Choose the 3d cursor on the toolbar on the left and click on the vertex of the block to place the 3d cursor on the location that you would like to align.  If you click near the vertex, the cursor will snap to it.  It is sometimes difficult to choose a 3d location on a 2d screen, so you should rotate the view to make sure the 3d cursor is at the correct location

.

• After moving the 3d cursor, choose either Select Box or Move in the toolbar on the left or you risk moving the cursor somewhere else.

6. Make sure the purple block is still selected.  Press Shift+S to open the pie menu again and choose Selection to Cursor (top).  The edge of the purple block will now be aligned with the corner of the turquoise block.
7. You may want to move the origin of the purple block back to the center.  To do that, choose Set Origin–Origin to Geometry in either the right mouse button menu or the Object menu in the 3D View.