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..::automatic optimisation::..

Enlarge Screenshot Producing automatic optimisation is relatively straight-forward. The principle is akin to that of the LOD (Level of Detail) Utility feature; depending on the distance to the camera, a higher or lower polygon version of the object needs to be displayed. While the LOD Utility is handy, it does increase workload by having to produce multiple versions of the same object. But what if we can do this on the fly?
Enlarge Screenshot The solution is quite simple. Firstly, we have all of the tools natively to perform the task, which can be found in the shape of the MultiRes modifier – an adaptive mesh optimiser that doesn’t screw up your mapping like the old Optimize modifier! However, once the calculations are generated you are fixed with a single percentage spinner value, though as with everything in 3ds max, this can be controlled by an additional controller, specifically an Expression controller.
Enlarge Screenshot This particular expression calls on two objects in the scene, specifically the Camera you are rendering from and the object that is to be optimised. In the screenshot, as there are multiple object present in the scene, a helper object is used instead. The expression simply measures the distance between the two positions and produces a higher value the shorter the distance, generating a percentage value.
Download the max file! Zip file to accompany.

..::quick tip::..

The MultiRes modifier needs to produce its calculations in the Viewport; unfortunately it can’t produce the necessary calculations at render time, so having modifiers that deform the surface beneath this particular modifier will cause the MultiRes to fail.

Initially published: 3D World magazine, Issue 98, Winter 2007.

Copyright Pete Draper, November 2007. Reproduction without permission prohibited.