Mesh/Decomposing a mesh for physics shape

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KBcaution.png Important: This article has been translated. The translation was imported on Aug 19 2011. Any changes will require re-export for incremental translation.

This tab is the second step in the model upload process.

A model's physics shape defines how it collides with other objects, and is typically simpler than its visual appearance to reduce computational cost. For example, a complex vehicle model might have a square physical box shape. NOTE: Models meant to be used as vehicles must not have a physics weight higher than 32.

Step 2: Analyze and Step 3: Simplify are not mandatory for creating a physics shape for your model, but can significantly decrease your model's physics weight.

After you make selections in this tab, click the Modifiers tab.

Step 1: Level of Detail

Choose one...   Select a level of detail to automatically generate a physics model based on an existing visual level of detail:
  • Lowest
  • Low
  • Medium
  • High
  • From file (see below)

Lowest or Low are adequate for most purposes and incur a relatively small physics cost.

From file   Select this option to upload your own physical model from a .dae file. This gives you the greatest control over the model's physics shape. Click Browse to select a file.

Step 2: Analyze

Select options in this section, then click Analyze.

Method   Select a decomposition method for the model. Each method is best suited to a particular type of shape, because it will return the most accurate and least costly results for models of that type:
  • Surface - best for curved, organic shapes, such as an animal body.
  • Solid - best for objects with sharp angles and a clear inside and outside, like buildings.
  • Wrap - best for very complex shapes, such as trees and branches.
Quality   Select how much combining and overlap reduction is performed on the hulls at the decomposition stage. High returns the best simplification results, but requires the most time to process. If you experience performance problems, try Preview setting first to confirm your smoothing and select Close Holes, then switch to High to get the best simplification results.
Smooth   Set the tolerance to which coplanar triangles are merged. The value is the angle between adjacent triangles for which merging is permitted. A value of zero allows some angle between triangles, resulting in gently-curving surfaces being flattened.

A lower Smooth setting results in a lower physics cost for objects with curved surfaces.

Close Holes (slow)   Select to fill any holes in the physical representation of the model (if possible) to fix minor errors in the model. Selecting this option will also close intentional openings in objects: do not use for models that have intentional openings, such as door frames.

Step 3: Simplify

Select options in this section, then click Simplify.

Method   Select a simplification method:
  • Retain %: Select a percentage of the hulls to retain from the original analysis.
  • Detail: Reduces the complexity of the physics model based on the Detail Scale slider.
  • Better Detail: Similar to Detail, but does a better job preserving openings in your model.
Passes   Increase this value to create results with fewer overlapping hulls and more accurate overall representation of your model's physical shape.
Detail Scale   Reduce this number to preserve more fine detail in your model during the simplification process. Larger values result in a decreased physics cost, but lower accuracy in the physics model. For many models, most of the simplification takes place at very low values, between 0.0 and 0.3, after which the physics model is reduced to a single hull.
Preview Spread   Move the Preview Spread slider (below the Preview pane) to explode your view of the hulls that comprise your physical model. Make sure the Physics box below the Preview pane is also checked. On objects with many hulls, this can help you to find and examine hulls that would not otherwise be entirely visible.