Spiky Sphere

Finding the Sphere tool

The Sphere tool is part of ShapeWizards suite called MagicBox (the other tools in the suite are Pursuit, Shell, Spiral). You can install all these tools at once by downloading and opening MagicBox.rbz, or you can install individual tools by downloading and opening separate tool files (Shere.rbz,...). Regardless of what method you choose, the tool icon will always end up in the ShapeWizards toolbox.

By default, this toolbox is a floating window and can appear anywhere on the screen. If you can't locate it, make sure that the menu item View/Toolbars/ShapeWizards is checked off and that the toolbar was not put so far from the window center that it was clipped out of the view. If you still can't see it, restart Sketchup. That will not be required often, but it can happen if you install several tools incrementally, or update a tool that has already been installed.

Unless docked, the ShapeWizards toolbox looks like this:

In this tutorial, the toolbox is docked at left vertical edge of Sketchup window, so that it doesn't interfere with the graphics.

Your first sphere

1. Start with an empty drawing, delete the Sketchup figure if necessary.2. Select top view by clicking on Camera/Standard Views/Top3. Activate Sphere tool by clicking on the Sphere icon in the ShapeWizards toolbox. If

you don't recognize it, move the mouse over the toolbox and the tool-tip will tell you. The prompt at the bottom of Sketchup window should read “SpikySphere”. After the

SpikySphere tool has been activated, the prompt should change to “SpikySphere: Push right mouse button for menu options”

4. Open the Sphere context menu by pushing the right mouse button and select Create from the menu. The prompt will change to “SpikySphere: Specify sphere center” and thecursor tip will be augmented by a small yellow dot representing the location of the Sphere object you are creating.

5. As you move the mouse around (without clicking), the VCB box (value control box) at the bottom of Sketchup window will show the running coordinates of the yellow dot in current units. Move the cursor to the origin and click. That will fix the center of the Sphere object to [0,0,0] and the prompt will change to “SpikySphere: Specify radius point / Enter radius”. The yellow dot will change to yellow circle which represents the size of the sphere. The current radius of the circle will be dynamically displayed in the VCB box.

6. Enlarge the circle to you liking and click. You just created your first sphere.

Well – sort of, because the object you created is actually a polyhedron with 20 faces and can be hardly mistaken for true sphere. You will learn shortly how to increase the number of faces and improve the appearance so that it does look like a real sphere. Also, the center of the sphere is not at theorigin as you might expect, but it is shifted up along the Z axis by the radius. The sphere is actually sitting on the XY plane so that all faces can be visible (see paragraph Sphere geometry)

Smoothness

It is easy to make the polyhedron look more like a sphere – just replace the polyhedron with another one that has larger number of faces.

1. Click on the Sphere object to select it (it will turn blue), open the context menu by pushing down the right mouse button and select Settings/Smoothness/Level 1

2. The current polyhedron will be replaced with this one:

3. Looks better, but it may still not be good enough, so let's try a different level. Select the sphere by clicking on it and then choose Settings/Smoothness/Level 3 from the context menu. You may wait a little, since there are a lot of faces to generate...

Edge visibility

4. There is a trade-off between rendering quality and speed of interaction, so try to avoid the last smoothness level, unless a very high rendering quality is required. Select the Sphere object, then invoke the delete function from the context menu and erase it.

5. Create a new Sphere object, select it and change the smoothness to level 2 by selecting Settings/Smoothness/Level 2 from the context menu. Select it again and invoke the Settings/Edge Visibility/Show Level 1 function.

6. The density of edges on the sphere will double, the smoothness remains the same. The density of edges and the smoothness levels are independent parameters, you can set smoothness at one level and choose to display edges from different level.

7. If you increase the edge visibility level to 2 by invoking Settings/Edge visibility/Show Level 2 (you need to select the Sphere object first), you'll see this:

This is as high as you can go with smoothness level set to Level 2. You can't display edges fromlevels that don't exist.

Face transparency

While edge visibility is controlled by specifying what you want to see, face visibility is controlled by specifying what you want to hide.

8. Select the Sphere object and open the context menu by pushing the right mouse button down. Select Settings/Face transparency/Hide Level 2 from the context menu.

9. As you see some of the faces from level 2 become transparent. The selection is somewhat arbitrary, but it follows two rules – transparent faces are higher levels are smaller than at lower levels and the distribution is even.

10. The face transparency doesn't change edge visibility, the picture above shows all edges at level 2 being visible as they were before. Edges create nice boundaries around transparent regions, but are somewhat disturbing when they cross opaque faces. Fortunately, there is a remedy for that. Select the sphere object by clicking at it, open context menu and remove the check off mark at Settings/Edge visibility/Show face edges. This will prevent the SpikySphere tool from rendering edges crossing solid regions.

11. Edges that cross holes pose a similar problem as illustrated on the following example. Select the Sphere object and lower the face transparency by activating Settings/Face transparency/Hide Level 1.

12. The visible edges that cross the holes can be removed by clearing the check-off mark in Settings/Edge visibility/Show hole edges.

13. You may wish to have hole edges invisible in most cases, but sometimes they may comehandy, like in wire-frames for example. Select the Sphere object and set the hole edges visibility ON by checking off Settings/Edge visibility/Show hole edges. Select the sphere again and check off Settings/Face transparency/Level 0.

14. With hole edges made visible and all face made invisible, the sphere will be rendered as wire-frame.

Spikes

15. Spikes are where the sphere ends and the fun begins. Delete the Sphere object (select,delete) and create a new one, using default values. Select it and invoke Settings/Spike distribution/Regular/Level 0 from context menu.

16. The sphere turns yellow with 3 extra edges inside each face. The edges are sides of a triangular spike, which is initially flush-aligned with the face.

17. Select the sphere and activate Change/Spike size.

18. The blue dot at the cursor tip is a reminder that dragging is in order. Push the left mouse button down and drag the mouse in the direction indicated by yellow arrow. As you do that, the spikes will enlarge or shrink depending on the direction of the move.

19. Select the sphere and increase the smoothness by Settings/Smoothness/Level 1

20. Do it again. Select the sphere and choose Settings/Smoothness/Level 2

21. And if you are patient, do it again with Settings/Smoothness/Level 3

22. Select the sphere and check off the option Settings/Spike distribution/Random.

23. Select the sphere again and activate Change/Spike random density

24. Push the left mouse button and drag the mouse in the direction indicated by the yellow arrow. Watch the spikes appear and disappear as you move the mouse left and right.

25. You can change the size of spikes in the same way. Select the sphere, activate Change/Radius from context menu and drag the mouse. The spike size will change dynamically.

Copy, delete, release

1. Start with a empty scene and set the viewpoint to Camera/Standard Views/ISO. Create a new Sphere object, select it and activate Copy from the context menu.

2. A copy of the Sphere object will be created and highlighted with yellow outline. The prompt at the bottom will change to “SpikySphere: Drag the copy to new location.”

3. Push left mouse button and drag the copy away.

4. When you release the button, you'll have a brand new copy made.

5. Delete is the same as erase in standard Sketchup – select and object and activate Delete from Sphere context menu. The Release function turns a Sphere object into regular Sketchup group (more about it in the next paragraph).

Sphere objects and groups

SpikySphere tool creates SpikySphere objects (or just Sphere objects), which can be manipulated by the SpikySphere tool and by other Sketchup tools as well. A Sphere object is a group offaces augmented by a set of hidden attributes accessible only to the Sphere tool. You can purge the attributes from the group by invoking the Sphere tool's Release command, which will transform Sphereobject to regular Sketchup group.

The Sphere tool uses Sphere objects differently from other Sketchup tools. Whereas a Sketchup tool treats a Sphere object as a group of connected faces, the Sphere tool treats it as a parametrically defined entity with faces generated algorithmically. The distinction between there two concepts is graphically represented by two different way of highlighting. If you select a Sphere object as a group offaces (accessible to standard Sketchup tools), the object will be highlighted as a group with blue/red frame around it. If you select the same Sphere object as parametrized entity (accessible to Sphere tool), the object itself will turn blue and there will be no frame.

How do you tell which case will apply when? The rule is simple – if the Sphere tool is active, all Sphere objects will be treated as parametrized entities, if the Sphere tool is deactivated, all Sphere objects will be treated as groups of faces.

When the Sphere tool is active, the only selection method available is one-click selection. Thereis no multiple selections, nor any other kind of selections, you can select only one object at a time. Let'sillustrate this on the two objects you just created.

1. Click on the right sphere, It will turn blue which indicates that a) it is selected, b) it is a parametric object and not just a group of faces. This is what you should see on the screen:

2. Leaving the blue sphere selected (select it again if you deselected in the meantime), bring up the context menu by pushing the right mouse button and activate Release.

3. The Release function deletes all hidden attributes and turns the Sphere object into a regular Sketchup group. Visually however, both spheres look the same, so how do we tell the difference? This is important, since the Sphere tool can handle only Sphere objects. Well, let's just try it. First click on the left sphere, which you didn't change, and you'll get this:

4. The sphere was selected, which indicates that it is a parametric object. Now click on the right sphere and see what happens.

5. Oops!, but you already know that, didn't you? The Sphere tool can handle only Sphere objects. Let's explore what happens when the Sphere tool is not active. Deactivate the Sphere tool by clicking at the arrow in the upper left corner of the Sketchup window andthen select the left sphere. It will be selected as a group with a red frame around it. Push the right mouse button and bring up Entity Info. The name of the group is “ShapeWizard's SpikySphere” and the group is locked. That is an indication that the group is actually a Sphere parametric object.

6. Now click on the right sphere.

The right sphere is an unlocked group with no name. That is an indication the it is just a group of faces.

Applying standard Sketchup tools on Sphere objects requires some caution, since it may lead to unexpected results. For example, if you open the Sphere group and delete one of the faces, the change will be lost next time you apply the Sphere tool on the object. There are only handful of Sketchup tools that can be applied safely to Sphere objects – Erase, Move, Rotate and painting faces with color. If you need to use some other tools, change the Sphere object into regular Sketchup group by invoking the Release command from Sphere context menu.

Drawing in space

All objects so far were created on the XY plane, but you can create Sphere objects on any plane derived from any face in the scene. Here is a simple example.

1. Start with an empty drawing, set viewing direction to Camera/Standard Views/ISO.2. Create a box by pushing up a rectangle created in the XY plane.

3. Activate the Sphere tool, select Create from the Sphere context menu and click on the center of the front-facing face. Move the mouse away from the center until you are satisfied with the size of the yellow circle.

4. Click again and watch the Sphere object appear on the front-facing vertical face.

Sphere geometry

SpikySphere is a sphere with adjustable resolution that can be morphed into several sphere-like shapes. The geometric resolution, or smoothness as it is referred to in the main menu, is the number of faces representing the sphere. The resolution ranges from 20 faces at Level_0 to 1280 faces at Level_3.

Each face is bound by 3 edges and you can choose which edges should be displayed, independently of the geometric resolution. For example if you set smoothness to Level_3 and edge visibility to Level_0, only edges corresponding to the basic 20 faces will be displayed, but the higher geometric resolution of Level_3 will be maintained, so they will appear curved instead of straight.

Making some faces transparent breaks the sphere into 'visible' and 'invisible' regions, which are independent of the geometric resolution. When you set transparency to certain level, let's say Level 1, itis Level 1 faces that will define the transparent regions, regardless how you set the geometric resolution. You may increase the geometric resolution to Level 3, but the transparent regions will look the same as if you used geometric resolution of Level 1.

How are the transparent regions defined ? That is determined by the face subdivision algorithm, that breaks each face (triangle) into 4 smaller triangles when you push the geometric resolution one step up. The middle triangle in the subdivision will be made transparent, the remaining 3 will stay opaque.

Default values and other notes

➢ When you create a new Sphere object, most of the parameters are set automatically do default values. The only exception is the radius that has to be defined explicitly. You can set default values in the same way as you ca specify parameter values for a specific object. The rule is this;

If there is a Sphere object selected, all values entered will be applied to that objectIf there is no Sphere object selected, all values entered will be taken as default values

➢ To find out which of the parameter values can be set as defaults, open the context menu when nothing is selected and look at the menu items. Those rendered in black can be set as defaults, those that are grayed out cannot be set as defaults.

➢ Numerical entries in the VCB box can be of 3 types – numbers, points, vectors. Positive values allow incremental editing, which means that if you prefix the entry with a sign, the entry will beadded or subtracted from the current value shown in the VCB box A point can be entered as a triple of numbers x,y,z or [x,y,z]. A vector has to be entered as <x,y,z>. The coordinates refer to the global Sketchup coordinate system.

➢ A selected Sphere object can be moved around by dragging. Place the cursor on the selected Sphere object and drag it away in the same way as you would drag a copy of the object.

➢ A useful tip: If you see some faces missing or being cut into be the front clipping plane, press Ctr-Shift-E to update the scene extents. That should fix it.

➢ How to uninstall Sphere tool ? Delete Sphere directory in Sketchup's Plugins/ShapeWizards directory.

➢ How to uninstall all ShapeWizards tools ? Delete the file shapewizards.rb and the directory ShapeWizards in Sketchup's Plugins directory.