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| {{Multi-lang}} | | {{Multi-lang}} |
| {{Navbox/Mesh|basics}} | | {{Navbox/Mesh|advanced}} |
| __NOTOC__
| | {{:Viewerhelp:Upload_Model_-_Physics}} |
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| [[Image:MeshWalkthrough-Decomposing Physics-Splash.png|300px]]
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| This tutorial will go through how to make the physical shape that can be bumped into.
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| One key thing to understand is that the model that you see, and the model that you bump into, can be defined by different meshes. We want to make a physical shape that is just detailed enough to give the ''illusion'' that you are bumping into the shape that you see, because if the physical shape is extremely detailed, the simulator will slow down when the model collides with objects or avatars.
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| == Get a Second Life compatible mesh file ==
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| The first step is to get a mesh file that you want to upload to Second Life. Second Life's mesh import is able to read [https://collada.org/mediawiki/index.php/COLLADA_-_Digital_Asset_and_FX_Exchange_Schema COLLADA] ("''.dae''") files. For the purposes of creating a physics shape, you can use pretty much any model that you can successfully import into Second Life, so we'll use the basic duck here.
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| # Click this link -- https://collada.org/owl/download.php?sess=0&parent=126&expand=1&order=name&curview=0&binary=1&id=698/ -- to download the "''duck.dae''" COLLADA file.
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| # Save the file anywhere on your hard drive where you can find it later.
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| == Upload the mesh file to Second Life ==
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| Next, take the file that you downloaded to your computer and upload it to Second Life:
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| # Select '''Build > Upload > Model...'''.
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| #: Alternatively, open My Inventory, click the '''+''' button, and select '''Upload > Model...'''.
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| #: A file dialog box opens.
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| # Find and select the <code>duck.dae</code> file from your computer.
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| #: The Upload Model window appears.
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| # Enter a name for your model in the '''Name''' field.
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| # Select the '''Show Physics''' checkbox.
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| #:[[File:Mesh_upload_model_show_physics.png|300px|Upload Model window with Show Physics checkbox]]
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| # In the '''Level of Detail''' tab, select the '''Auto generate''' radio button, and click '''Generate'''.
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| #: The numbers in the Triangles and Vertices column of the table at the top have changed.
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| #:[[File:Mesh_upload_model_LoD_generate.png|300px|Level of Detail tab after Generate]]
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| # In the '''Physics''' tab, select the '''Use Level of Detail''' radio button, and select '''Medium''' in the dropdown.
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| #: Yellow lines appear on the surface of your model.
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| #:[[File:Mesh_upload_model_physics_LoD_medium.png|300px|Physics tab before Optimize]]
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| # Click the '''Optimize''' button.
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| #: The Step 2: Decompose screen appears.
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| #:[[File:Mesh_upload_model_physics_optimize.png|300px|Physics tab after Optimize]]
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| # Click the '''Decompose''' button.
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| #: The Step 3: Simplify screen appears, and after a few seconds, your model is covered with colored triangles.
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| #:[[File:Mesh_upload_model_physics_decompose.png|300px|Decomposition results]]
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| # Move the '''Explode''' slider to see the decomposed shape.
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| #: Note: The Explode slider does not change the decomposed shape, it only moves it away from the Mesh so you can see it clearly.
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| #:[[File:Mesh_upload_model_physics_decompose_explode.png|300px|Explode view]]
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| # Set the '''Detail Scale''' slider to '''0.081'''.
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| # Under Simplify Method, select '''Detail''' from the dropdown menu.
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| # Click the '''Simplify''' button.
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| #: The decomposed pieces are simplified into a few objects.
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| #:[[File:Mesh_upload_model_physics_simplify.png|300px|Simplified decomposition]]
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| # Click the '''Upload''' button to upload the mesh with this simplified physics shape.
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| == Add your mesh object to the world ==
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| [[File:MeshWalkthrough-Physics_Shapes_setting.png|right|200px|thumb|Physics Shape display]]
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| You can now add your model to the world and view its physics decomposition.
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| # In My Inventory, find '''LOD3spShape''' in your '''Objects''' folder.
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| #: If you're having trouble or have a large inventory, use your inventory's '''RECENT''' tab.
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| # Drag '''LOD3spShape''' from your '''Objects''' folder to anywhere on the ground where you have permissions to build.
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| #: A duck model appears on the ground.
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| #: This model is now physics-enabled, meaning that it can interact with other physics items in the world.
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| # Enable the '''Develop''' menu by entering {{K|Ctrl|Alt|Q}}.
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| #: A new '''Develop''' menu appears in your main menu bar.
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| # Select '''Develop > Render Metadata > Physics Shapes'''.
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| #:[[File:MeshWalkthrough-Physics_Shape_efficiency_visualized.png|right|200px|thumb|Physics Efficiency]]
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| #: Your object appears with a color overlay which indicates how efficient its physics representation is. Aim to have the physics overlay appear in '''blue''':
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| #:* A blue overlay indicates the object's physics are efficient and will produce very little load on the sim.
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| #:* A red overlay indicates the object could potentially cause high physics lag on the region.
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| # Right-click the duck and select '''Edit'''.
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| # Open the '''Object''' tab in the edit window.
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| # Next to Physics Shape Type, select '''Prim'''.
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| #: The blue overlay changes to display the more accurate physics shape you created.
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| This is the end of the mesh tutorial. Visit the '''[[Mesh | Mesh main page]]''' for more information.
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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...
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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.
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| From file
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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.
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Step 2: Analyze
Select options in this section, then click Analyze.
| Method
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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.
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| Quality
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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.
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| Smooth
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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.
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| Close Holes (slow)
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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.
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Step 3: Simplify
Select options in this section, then click Simplify.
| Method
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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.
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| Passes
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Increase this value to create results with fewer overlapping hulls and more accurate overall representation of your model's physical shape.
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| Detail Scale
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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.
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| Preview Spread
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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.
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