mr Proxy Objects

by Joy Voltenburg
Multimedia Consultant
Autodesk Certified Instructor - 3ds Max

I’d like to show you a new tool in 3ds Max Design 2009 that will help you control system resources. The new mr Proxy object is extremely useful when you have a scene that contains many instances of an object, such as an auditorium with hundreds or thousands of instances of a seat model. It is also particularly useful for objects with extremely high polygon counts, in that it eliminates both the conversion to mental ray format and the presence of the source object at render time, thus saving time and freeing up a great deal of memory for rendering.

Let me demonstrate the method of adding an mr Proxy object to your scene and also its placement. First, create a teapot in your scene. This will be your reference object. Next, go to the create panel rollout and select mental ray as the type of object. Then select mr Proxy.

Place the mr Proxy object in your scene. It’s displayed as a bounding box. Next (very important), select the modify panel. You’ll need to be in the modify panel in order to associate the mr Proxy object with the teapot. Click the source object button, which currently reads “None,” and then select the source object. The name of the source object appears on the button.

(If you plan to modify the source object, do so before converting it to mr Proxy format. Because the mr Proxy geometry is loaded by mental ray at render time, the renderer ignores any modifiers that change the geometry. The one exception is the Skew modifier, which affects the object’s transformation matrix rather than its sub-object geometry, and thus can modify a proxy.)

Click the Write Object To File button, enter a file name, and click Save. This opens the mr Proxy Creation dialog, which lets you set parameters for the proxy object file, including animation frames and preview settings. (The preview will reflect whichever viewport was active when you saved the file.) Change settings as necessary and then click OK to continue. The file is saved in the MIB format and its path and file name are placed in the Proxy File field. After you save the file, the Display group shows the proxy geometry and the viewport shows the object, by default, as a point cloud: a group of vertices that roughly defines the object’s shape. Increase the number of points in the cloud (try different numbers until you get a fair representation).

You can delete the original teapot now and just use the mr Proxy object. You can now use this object as any other object in 3ds Max Design, applying materials, copying it, transforming (move, rotate, scale), animating with it, and so on.

Using materials with the mr Proxy object

When you convert an object to an mr Proxy, the proxy does not inherit the object’s material. You can apply a material to all of the mr Proxy objects or different materials to different groups of mr Proxy objects. But, if you wish the mr Proxy object to use the original object’s material, an efficient way to handle this is with the XRef material.

1. Create or load the object that is to serve as the source object. Apply any necessary modifiers and material, and then save a copy.

2. Create the mr Proxy object and then convert the source object, as described in the preceding procedure. Delete the source object.

3. Apply an XRef material to the proxy object.

4. Set the material to use the material from the source object file you saved in step 1.

Then, to modify the material on the proxy, load the source object, edit its material, and save the file. Because the material on the proxy object is externally referenced, it updates automatically.

Animation

The mr Proxy object supports vertex-level animation as well as topological changes in the source object. The software writes a pair of files (geometry and thumbnail) for each animation frame. You control animation playback in the Proxy object with the Animation Support group settings. When you save or load an animated Proxy, the software automatically enables the On check box in this group and sets Frames to the number of frames in the animation. You can change the value to the number of frames you want to use from the animation. Also, you can adjust the rate at which the animation appears in the proxy object by adjusting the Replay Speed value, and change the frame at which the playback begins with the Frame Offset parameter.

Placement

An easy way to place and orient the mr Proxy object in your scene is with the Clone and Align tool. For example, if in Revit you had created stand-ins for chairs in your scene, you could select the mr Proxy object, open the Clone and Align dialog box and do either of the following:

On the Clone Parameters rollout, choose the type of clone, and, if appropriate, how to copy the controller. Use the Clone Parameters rollout settings to specify position, orientation, and scale options. At any time, when Pick is off, you can change the source selection in a viewport. This causes the dialog to lose focus; click it again to regain focus and refresh the viewport preview of the clone operation. To make the clones permanent, click Apply, and then click Cancel or the close button. See following example:

Before – mr Proxy object with rectangle stand-ins:


After – placement and orientation with the Clone and Align tool: