Objects are the basic components of SketchyPhysics simulations. To create one, simply draw somethng with SketchUp and group it. Only groups are recognized as objects by the physics engine (non-grouped surfaces/edges/volumes will be intangible).

You can also create objects with appropriate shapes already applied using the shapes toolbar.

Remember that when you create a custom object you have to set the appropriate physics shape. If you're not sure, it's normally a good idea to use a 'convex hull'.

Editing Objects after Grouping[]

You've made your "functioning machine", but need to edit the objects; you do NOT have to "disconnect" the joint connector tool from the Parent Object, then "Explode" the grouped objects, and then edit them.

Simply left-click the group with the "target object" to be edited. Repeat, only until the target object is selected. Now edit the object. eg. rotate, scale, move, make a hole, etc. To make it "accept" the edits, just left-click outside the original grouped object. Each subsequent click will revert back to the orginal grouping.

You can edit as far back as the original oject shape, with no bounding box.

Object properties[]

All the objects have those properties, which can be modified via the UI or the contextual menu.

Center of gravity (COG)[]

The center of gravity is a geometrical point positioned in the center of the boundary box of an object. It is the point used by the engine to calculate the influence of the gravity and magnets on the object. Remember that in complex objects the center of gravity is in the exact center. So if you group a box and a cylinder to make an hammer, the COG will be not in the hammer's head, but near the center of the handle. So, unexpected results may occur. This is one of the reasons behind the creation of the joints. If you want to create something with realistic COG, use for example, the "fixed" joint.


The three axes (red, green, blue) are a property of any object. The blue one is the most important because by default is used to determine the direction of emitters and thrusters.
Normal groups' axes are aligned to the model's axes. Sketchy Solids' axes are determined by the user's clicks.

Change axes direction

To change the emission axis of an object you can do two things:

  • right-click the group and select Make Component. Then right-click it again and select Change Axes. This will change the blue axis' position.(Sometimes components act strange during the simulation)
  • In the script formula, write [0,0,(formula)] or [(formula),0,0] or [0,(formula),0] to use another axis.
  • EDIT: Another way to change the axes is to go into the group and use the Axes tool to redirect the blue axes in any direction.


ignore Act like a non-grouped geometry.
static The object will NEVER move
frozen Similar to static, but will become movable when touched by a non-frozen object or clicked
ShowCollision The object will show his true physical shape. Used in debug.
magnetic The object will be influenced by magnets
NoCollision The object will act like movable "ignore"


default Like the box shape. When attributed to complex objects, will respect the sub-groups' shape
box Uses the selection box around the object as the shape
convexhull Any shape without convexities will be faithfully represented
staticmesh The visible shape of the object, included convexities, will be represented. But the object will be static.