Sign in to follow this  
steven katic

Shoemake's Mysterious Translation Controller

Recommended Posts

I am digging deep here: 999 times out of a thousand I can eventually find the information I need without posting on forum(s) [looks like I must be upto the thousand tolerance level :)]
Quote:
Since a single mouse position has only two degrees of freedom, a pair of positions—the ends of an arc—are used. This part of Arcball has wider applicability, including a translation controller to be described in a future paper. From: "ARCBALL: a user interface for specifying three-dimensional orientation using a mouse",Ken Shoemake,September 1992,Proceedings of the conference on Graphics interface '92
1992, 16 long years ago. This is about the mysterious 'translation controller to be described in a future paper'. Does anybody know if that future paper materialised over the last 16 years? The last cited Shoemake paper I could find was: "Arcball rotation control",Ken Shoemake, August 1994 Graphics gems IV. And most of his other papers seem to diverge into the discipline of animation. My conclusion so far is that Shoemake never got around to doing that 'translation controller' paper, or my understanding of that term is different to what he meant. OR Does anyone know of published works/papers by other authors that continued in Shoemake's footsteps towards describing a translation controller. Just to clarify: A brief description of my understanding of 'translation controller' can be found in my post(s) here

Share this post


Link to post
Share on other sites
Most 3d modeling software actually implement a trackball control in ordinary viewports. In most 3d software I've used, the feature is used by holding the middle mouse button down on a viewport and dragging an arc (or a line) with the mouse. The more curved the arc, the more the transform is rotated along the z axis (monitor-eye); conversely, if the drag is more linear, the transform is rotated along the axis crossing the drag line.

If you need some code, the DXUT system (free with source in the DirectX SDK) implements a complete trackball controller.

Share this post


Link to post
Share on other sites
Thanks for posting Niko2. I know about the trackball/arcball.
I am more interested in what Shoemake tried to convey in the quote I provided.

To me, it appears that Shoemake was suggesting that the concept of mapping the 2 DOF of the mouse (pointer positions) can be used to translate objects in a 3D space in a similar fashion to the way the 2 mouse pointer positions are used via a virtual trackball to rotate objects. An example of using the mouse as a translation controller in a way (I thought I understood) Shoemake suggests can be found here

I am now thinking that I will never know what he really meant in that quote (I provided) until I actually contact the author directly and ask him.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this