General

Exporting a mesh to a file

Exporting a mesh from the GUI

The .vrmesh file format

Importing VRay Proxy

Proxy parameters

Notes

 

Search Keywords: proxy, mesh, VRayMesh, Alembic, .vrmesh, .abc

General

VRayProxy allows you to import geometry from an external mesh file which can be either VRayMesh or Alembic file. The geometry is not present in the scene during modeling and does not consume any resources. This allows the rendering of scenes with very heavy geometry. At render time, V-Ray will load the actual geometry (instead of the preview) as needed.

Exporting a mesh to a file

Before you can import a mesh through a VRayProxy object, you need to create the mesh file first. This can be done through the Softimage interface.

Exporting a mesh from the GUI

To export a .vrmesh file from the user interface, open the scene where you have the object(s) you'd like to export as VRayProxy objects, select the object(s) and from the File menu choose Export > Export to (.vrmesh). This will bring out the create proxy dialog:

 

Folder - this is the directory where the mesh file will be created.

 

File Name - this is the name of the file, if you have selected the Export all selected objects in a single file option. You don't need to specify a path - the Path folder will be used.

 

Export all selected objects in a single file - this option will take all selected objects and will merge them into one mesh file. This option also stores the transformations of the selected objects. When you import the file with a proxy object, it must be centered at the origin, if you want the objects to be in the same place.

 

Export each selected object in a separate file - this option will create one file for each selected object. The name of each file is derived from the name of the corresponding Softimage node. The transformation of an object is not included in its mesh file, and the corresponding proxy must have the same transformation as the original object, if it is to appear in the same place. Note that you can use this option even with a single object, which will cause the object pivot to be preserved in the exported .vrmesh file.

 

Group faces in output - this option allows you to group multiple faces by assigning them an unique material ID. This is useful during shading when different parts of the proxy need to be shaded differently.

 

by assigned material - when this option is selected faces that have the same material will be assigned the same Material ID

 

by map to existing clusters - when the faces in the geometry have been previously divided into clusters this options assigns the same material ID to the faces in each cluster regardless of the material assigned to individual faces.

Overwrite existing vrmesh file - when checked V-Ray will automatically overwrite any existing vrmesh files.

 

Animation

 

Enable - if the mesh is animated you can export that animation in the .vrmesh file by enabling this option. Note that when exporting each mesh to a separate file, only the vertex animation will be included in the file. Any animations that are part of the transformations of the original mesh will be left there.

 

Frame range - allows you to specify the number of frames to be exported

 

Timeline - exports all the frames in the animation timeline

 

Specify - manually specify the frame range to be exported by using the Start and End parameters

 

Export velocity - checking this option will export velocity information for the moving objects. This makes it possible to add motion blur to the final animation. However exporting this extra information takes longer. If you are not going to need motion blur it makes sense to disable this option.

 

Interval start - specifies the beginning of the range for which velocity information will be exported

 

Interval end - specifies the end of the range for which velocity information will be exported

 

Automatically create proxies - this option will create proxy objects for the exported meshes. The proxies will have the correct transformations and materials derived from the original objects. If Export each selected object in a separate file is selected, the transformations of the original meshes will be used, otherwise a new transformation will be created and the original objects will be deleted.

 

Faces in preview - allows you to specify how many faces are going to be used to show a preview of the proxy in the viewport.

The .vrmesh file format

Meshes are exported to a special .vrmesh file format. It contains all geometric information for a mesh - vertices and face topology as well as texture channels, face material IDs, smoothing groups, normals - in short, everything that is needed to render the mesh. In addition, the mesh is preprocessed and subdivided into chunks for easier access. The file also contains a simplified version of the mesh used for preview purposes in the viewports. More information about the .vrmesh file format is available in the documentation of the V-Ray SDK.

 

It is important to realize that the mesh is in a "ready to render" format. No further modifications to the mesh are expected. You can't apply modifiers to the mesh, or animate it in any way except if you animate the position/orientation of the proxy object. There is no way to recover the original mesh from a .vrmesh file (this can be done in principle, but is currently not supported). Therefore, if you plan on doing modifications to the mesh, you should keep it in a Softimage file (which may be different from the file that gets rendered in the end).

Importing VRay Proxy

The ImportVrayMeshOptions dialog allows you to import both .vrmesh files and also alembic meshes including animation.

 

Import ProxyTo import a .vrmesh/.abc file as a proxy you need to go to File>Import>Import VRay Proxy... This will bring out the import V-Ray Proxy menu.

 

Mesh File - specifies the mesh file to be loaded as a proxy

 

Display - this option controls how the imported mesh is displayed

 

bounding box - the proxy is displayed as its bounding box

 

preview from file - the information in the mesh file is used to generate a simplified preview of the geometry

 

Mesh contains animation - this check box allows us to specify whether or not the proxy is animated.

 

Proxy parameters

 

Mesh File Path - this is the source mesh file. Animated proxies can be stored either in one single file, or as a sequence of files with one file per frame. In the latter case, you can use the string %0nd in the file name to have it replaced with the current frame number at render time, where n is an integer number specifying the number of digits. For example, if you enter my_proxy_%04d.vrmesh as the file name, this will be expanded to my_proxy_0000.vrmesh for frame 0, my_proxy_0001.vrmesh for frame 1, and so on. If you use a sequence of files, the Playback type option will be ignored, as V-Ray won't know how many frames are in the animation. The Playback speed parameter may also work unreliably with sequences of files.

 

Display Type - controls how the V-Ray Proxy will be displayed in the viewport

 

bounding box - when this option is on the mesh is represented as a box in the viewports.

 

preview from file - when this option is enabled the mesh is represented using a low polygonal version of the original geometry

 

Animation Parameters

 

Playback speed - this is a multiplier for the speed of the animation. Putting negative numbers here will make the animation play backwards. This option may not work very well for sequences of .vrmesh files.

 

Start offset - use this parameter to offset the beginning of the animation by the given number of frames. You can use positive as well as negative values here.

 

Playback type - select a playback mode from the drop down menu.

 

Loop - the animation is looped by skipping to the first frame once it has finished

 

Play once - the animation is played once;

 

Ping-pong - the animation is looped by playing it backwards once the last frame has been reached and then playing it forward again when the first frame is reached;

 

Still - the animation is not played. Instead just one frame of the animation is shown. You can select which that frame is with the help of the Start offset parameter.

 

This option will be ignored if you use a sequence of separate .vrmesh files.

 

Alembic proxy parameters

 

Compute normals - enables or disables the computing of normals

 

Smooth angle - specifies the smooth angle in degrees

 

Number of faces in preview - controls the number of faces which will be used for displaying the mesh in the viewport

 

Notes