Meshes
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Meshes

At the core of any 3D game are Meshes - objects consisting of triangles, with textures applied.

Meshes in Unity are rendered with renderer components. Although there may be many variations, a Mesh Renderer is the most commonly used.


A Mesh Filter together with Mesh Renderer makes the model appear on screen.

Meshes

Meshes make up a large part of your 3D worlds. Unity doesn't have its own tools for mesh creation but has good interactivity with popular 3D modelling software. Importing meshes is mostly straightforward but the following pages note things that you need to watch out for with particular applications.

Other applications

Unity can read .FBX, .dae (Collada), .3DS, .dxf and .obj files, so any software that that can export any of these formats should work fine with Unity. FBX exporters for popular 3D packages can be found here. Many packages also have a Collada exporter available.

Textures

Unity will attempt to find the textures used by a mesh automatically on import by following a specific search plan. First, the importer will look for a sub-folder called Textures within the same folder as the mesh or in any parent folder. If this fails, an exhaustive search of all textures in the project will be carried out. Although slightly slower, the main disadvantage of the exhaustive search is that there could be two or more textures in the project with the same name. In this case, it is not guaranteed that the right one will be found.


Place your textures in a Textures folder at or above the asset's level

Import settings.

The Import Settings for a mesh file will be displayed in the inspector when the mesh is selected.


The Mesh Import Settings dialog
Meshes
Scale FactorUnity's physics system expects 1 meter in the game world to be 1 unit in the imported file. If you prefer to model at a different scale then you can compensate for it here.
Use File UnitsThis option is available only for 3dsMax files. If enabled it imports 3dsMax file with one Max unit equal to one Unity unit, otherwise it imports with 1 cm equal to 1 Unity unit.
Mesh CompressionIncreasing this value will reduce the file size of the mesh, but might introduce irregularities. It's best to turn it up as high as possible without the mesh looking too different from the uncompressed version. This is useful for optimizing game size.
Mesh OptimizationThis option determines the order in which triangles will be listed in the mesh.
Generate CollidersIf this is enabled, your meshes will be imported with Mesh Colliders automatically attached. This is useful for quickly generating a collision mesh for environment geometry, but should be avoided for geometry you will be moving. For more info see Colliders below.
Swap UVsUse this if lightmapped objects pick up the wrong UV channels. This will swap your primary and secondary UV channels.
Generate Lightmap UVsUse this to create the second UV channel to be used for Lightmapping.
Advanced OptionsSee Lightmapping UVs document.
Normals & Tangents
NormalsDefines if and how normals should be calculated. This is useful for optimizing game size.
ImportDefault option. Imports normals from the file.
CalculateCalculates normals based on Smoothing angle. If selected, the Smoothing Angle becomes enabled.
NoneDisables normals. Use this option if the mesh is neither normal mapped nor affected by realtime lighting.
TangentsDefines if and how tangents and binormals should be calculated. This is useful for optimizing game size.
ImportImports tangents and binormals from the file. This option is available only for FBX, Maya and 3dsMax files and only when normals are imported from the file.
CalculateDefault option. Calculates tangents and binormals. This option is available only when normals are either imported or calculated.
NoneDisables tangents and binormals. The mesh will have no Tangents, so won't work with normal-mapped shaders.
Smoothing AngleSets how sharp an edge has to be in order to be treated as a hard edge. It is also used to split normal map tangents.
Split TangentsEnable this if normal map lighting is broken by seams on your mesh. This usually only applies to characters.
Materials
Import MaterialsDisable this if you don't want materials to be generated. Default-Diffuse material will be used instead.
Material NamingControls how Unity materials are named:
<textureName>.matThe name of the diffuse texture of the imported material that will be used to name the material in Unity. When a diffuse texture is not assigned to the material, Unity will use the name of the imported material.
<materialName>.matThe name of the imported material will be used for naming the Unity material.
<modelFileName>-<materialName>.matThe name of the model file in combination with the name of the imported material will be used for naming the Unity material.
<textureName>.mat or <modelFileName>-<materialName>.mat (OBSOLETE)The name of the diffuse texture of the imported material will be used for naming the Unity material. When a diffuse texture is not assigned or it cannot be located in one of the Textures folders, then the material will be named <modelFileName>-<materialName>.mat instead. This option is backwards compatible with the behavior of Unity 3.4 (and earlier versions). We recommend using <textureName>.mat, because it is less complicated and has more consistent behavior.
Material SearchControls where Unity will try to locate existing materials using the name defined by the Material Naming option:
LocalUnity will try to find existing materials only in the "local" Materials folder, ie, the Materials subfolder which is the same folder as the model file.
Recursive-UpUnity will try to find existing materials in all Materials subfolders in all parent folders up to the Assets folder.
EverywhereUnity will try to find existing materials in all Unity project folders.
Animations
GenerationControls how animations are imported:
Don't ImportNo animation or skinning is imported.
Store in Original RootsAnimations are stored in the root objects of your animation package (these might be different from the root objects in Unity).
Store in NodesAnimations are stored together with the objects they animate. Use this when you have a complex animation setup and want full scripting control.
Store in RootAnimations are stored in the scene's transform root objects. Use this when animating anything that has a hierarchy.
Bake AnimationsEnable this when using IK or simulation in your animation package. Unity will convert to forward kinematics on import. This option is available only for Maya, 3dsMax and Cinema4D files.
Animation Wrap modeThe default Wrap Mode for the animation in the mesh being imported
DefaultThe animation plays as specified in the animation splitting options below.
OnceThe animation plays through to the end once and then stops.
LoopThe animation plays through and then restarts when the end is reached.
PingPongThe animation plays through and then plays in reverse from the end to the start, and so on.
ClampForeverThe animation plays through but the last frame is repeated indefinitely. This is not the same as Once mode because playback does not technically stop at the last frame (which is useful when blending animations).
Split AnimationsIf you have multiple animations in a single file, you can split it into multiple clips.
NameThe name of the split animation clip
StartThe first frame of this clip in the model file
EndThe last frame of this clip in the model file
WrapModeWhat the split clip does when the end of the animation is reached (this is identical to the wrap mode option described above).
LoopDepending on how the animation was created, one extra frame of animation may be required for the split clip to loop properly. If your looping animation doesn't look correct, try enabling this option.
Animation Compression
Anim. CompressionThe type of compression that will be applied to this mesh's animation(s)
OffDisables animation compression. This means that Unity doesn't reduce keyframe count on import, which leads to the highest precision animations, but slower performance and bigger file and runtime memory size. It is generally not advisable to use this option - if you need higher precision animation, you should enable keyframe reduction and lower allowed Animation Compression Error values instead.
Keyframe ReductionReduces keyframes on import. If selected, the Animation Compression Errors options are displayed.
Keyframe Reduction and CompressionReduces keyframes on import and compresses keyframes when storing animations in files. This affects only file size - the runtime memory size is the same as Keyframe Reduction. If selected, the Animation Compression Errors options are displayed.
Animation Compression ErrorsThese options are available only when keyframe reduction is enabled.
Rotation ErrorDefines how much rotation curves should be reduced. The smaller value you use - the higher precision you get.
Position ErrorDefines how much position curves should be reduced. The smaller value you use - the higher precision you get.
Scale ErrorDefines how much scale curves should be reduced. The smaller value you use - the higher precision you get.

Material Generation and Assignment

For each imported material Unity will apply the following rules:-

If material generation is disabled (i.e. Import Materials is unchecked), then it will assign the Default-Diffuse material. If it is enabled then it will do the following:

Colliders

Unity uses two main types of colliders: Mesh Colliders and Primitive Colliders. Mesh colliders are components that use imported mesh data and can be used for environment collision. When you enable Generate Colliders in the Import Settings, a Mesh collider is automatically added when the mesh is added to the Scene. It will be considered solid as far as the physics system is concerned.

If you are moving the object around (a car for example), you can not use Mesh colliders. Instead, you will have to use Primitive colliders. In this case you should disable the Generate Colliders setting.

Animations

Animations are automatically imported from the scene. For more details about animation import options see the Animation Import chapter.

Normal mapping and characters

If you have a character with a normal map that was generated from a high-polygon version of the model, you should import the game-quality version with a Smoothing angle of 180 degrees. This will prevent odd-looking seams in lighting due to tangent splitting. If the seams are still present with these settings, enable Split tangents across UV seams.

If you are converting a greyscale image into a normal map, you don't need to worry about this.

Hints

The Unity Editor shows too many triangles (compared to what my 3D app says)

This is correct. What you are looking at is the number of triangles actually being sent to OpenGLES for rendering. In addition to the case where the material requires them to be sent twice, other things like hard-normals and non-contiguous UVs increase vertex/triangle counts significantly compared to what a modeling app or Unity tells you. Triangles need to be contiguous in both 3D and UV space to form a strip, so when you have UV seams, degenerate triangles have to be made to form strips - this bumps up the count. Previously Unity would report triangle counts incorrectly. This was fixed first in the run-time, and recently in the Editor. Now both will report the correct number of triangles actually being sent to OpenGLES for rendering.

See Also

Page last updated: 2012-01-19