Viewerhelp:Upload Model - Physics

The physics decomposition step analyzes the model and generates a series of "hulls" that represent the physical shape of the model as it will be interpreted by Second Life's physics engine. Additional steps allow you to simplify the physics shape, thereby reducing the amount of load for the physics engine. Models meant to be used as vehicles must not have a physics cost higher than 32.

Step 1: Analysis

Method

Each of the three available decomposition methods is best suited to a particular type of shape, and will return the most accurate and least costly results when paired with a model of that type.

• Surface: Works best on curved, organic shapes, such as an animal body.
• Solid: Works best on objects with sharp angles and a clear inside and outside, like buildings.
• Wrap: Works best on very complex shapes, such as trees and branches.

Quality

These values determine 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 during this step, try using the Preview setting first in order to confirm your smoothing and Close Holes results, then switch to High to get the best simplification results.

Smooth

The Smooth value sets the tolerance when the utility tries to merge coplanar triangles. It refers to 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)

Attempts to fill any holes in the physical representation of the model in order to fix minor errors in the mesh. However, checking this setting also closes intentional openings in objects and should not be used for models that are meant to be passed through, such as door frames.

Step 2: 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

Increasing the number of passes creates results with fewer overlapping hulls and more accurate overall representation of your model's physical shape.

Detail Scale

Reducing this number preserves 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 to explode your view of the hulls that comprise your physical model. On objects with many hulls, this can help you to find and examine hulls that would not otherwise be entirely visible.