In 3D data preparation, it is often important to be able to control the triangle count of your model, because of the device performances that will display the model, for instance (e.g. a maximum of 100 000 triangles is recommanded for HoloLens)

That's the purpose of the Decimate To Target function: the user can conform the model's triangle count to his need.

You can switch between Triangle count, or Ratio (% of the total number of triangle of your selection)

Things to know about this function 

Selected GameObjects

Although this algorithm operates at Mesh level, it is based on the whole set of Meshes to evaluate the ratio or the triangle count. It means that calling the function with a list of 10 meshes is different that calling 10 times the function with a single mesh each time. In the first case, the target will be reached for the whole set of mesh, while it will be reached for each mesh individually in the second case. 

TIP        For AEC, it is advised to call the function a single time with a list of all of the meshes, so that meshes made of a very few triangles such as walls are kept intact while the decimation focuses on denser meshes. Otherwise, you can use the Rule Engine to apply decimation on each GameObject at once

Preserve Painted area

If the parameter is set to true, the function uses colored vertices to preserve painted area. Only vertices painted with a Red color (1, 0, 0) are considered.

 The left model vertices are painted with Polybrush, the center model is decimated without using "Preserve painted area", the right model is decimated using it. The red area is preserved.

Here is a tutorial to paint the vertex of your mesh.

WARNING        Some shaders can assign a default White value (1, 1, 1) to vertices. So the function takes in reality the difference between R and B as a vertex weight.

Advanced parameters

  • UV Importance: Select importances of texture coordinates. By default, the algo with preserve seems and reduce deformation but if you need faster decimation with less memory consumptions, you can decide to ignore it.
  • Protect Topology: If False, the topology of the mesh can change and some edge can become Non-manifold. If True, the decimation may take longer time or not reach the target expected. 

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