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Peparing a 3D File   

We suggest using AC3D for 3D media creation. A license is relatively cheap and AC3D has a lot of capability coupled with a decent UI that's pretty quick to learn. Another large advantage is, FlexSim is capable of directly importing the raw .ac files created from AC3D. You can get AC3D from

If you're not using AC3D, we suggest exporting media to the 3ds file format. The 3ds file format allows for very fast drawing speeds and fast load speeds. With several 3D formats, including .3ds and .ac files, you can:

  • Have the FlexSim object's color show through on certain parts of the shape
  • Use the FlexSim object's defined texture show through on certain parts of the shape
  • Auto-scale the FlexSim object based on 3D file dimensions

The following steps should be performed when preparing a 3D file for import:

Reduce the Number of Polygons

3D files typically include more information than is necessary. Removing excess polygons will improve the visual performance of your model. As a result, it will be easier to build and present the model.

Textures vs. Polygons

The use of well made textures can help a modeler reduce the number of polygons required to make a realistic looking object. Below are some pictures of low polygon 3D files in FlexSim. Also, where possible you should consolidate objects in your 3D creation software and share the same texture among multiple objects. This reduces the number of OpenGL state changes required, which can significantly improve performance.


Transparency in FlexSim is simple. It is just a matter of using textures that have transparency in them. You'll need to create your textures with a file type that supports transparency like a PNG file. FlexSim will read the transparency of the image and display it properly.

Adjust the Scale

3D files are not necessarily drawn in feet or meters and may need to be rescaled to work appropriately in FlexSim. There are three ways to adjust the scale of a 3D file:

  1. Appropriately scale the file in the 3D program.
  2. Scale the visual tool or other object in FlexSim that the file is imported into.
  3. Use an xrl file for wrl files.

If you are using 3DS or .ac, then you can just make sure the object is scaled properly in whatever 3D software you use. Then import it into FlexSim, and it will automatically import to the correct size. Just make sure that your units in your software are the same as the units you are going to use in FlexSim.

Getting the Object's Color to Bleed Through

For .3ds and .ac files, you can have the FlexSim object's color bleed through on certain shapes in the file. You can do this in one of two ways: (1) give the shape an ambient color value of rgb: (0.235,0.235,0.243) in your 3D software, (2) append "_fsclr" to the end of the shape's material name in your 3D software.

Getting the Object's Texture to Bleed Through

For .3ds and .ac files, you can also have the FlexSim object's defined texture show up on the shape instead of the texture defined in the file. To do this, just add a texture named "fstx.png" to the object in your 3D software.

XRL Files

xrl files are used to make imported wrl shapes conform to the object they are imported into. xrl files must have the same names as the objects they modify. For example:

  • crane.wrl – crane.xrl

xrl file makeup

The xrl file is a text file made up of 13 values separated by carriage returns. You can edit this file using notepad or wordpad, as shown below.

xrl file info

Spatial values determine the end size of the 3D shape. Offset values are the values required to get the 3D shape zeroed out and sized to 1,1,1. The centroid value is 1 or 0 and determines if the object rotates around the center of the object or the top left corner.

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paul.t contributed to this article


FlexSim 2016.1