How to create multi colored visual marker for Rviz?

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I think there is an issue with Rviz because of which colors in the Collada (.dae) mesh file are ignored. Here's what I did to solve the problem:

1) For each part of the 3D object, I added a different texture from image. Eg. for a red part, I used plain red colored image and added that as a texture to the object. I used Blender software for this.

2) Added these lines to the node that published the visualization marker:

  marker.mesh_resource = "package://rl_car/visual_models/car/car.dae";
  marker.mesh_use_embedded_materials = true;

It takes a few seconds for the marker to be visualized for the first time when I start Rviz, maybe because Rviz needs the time to load the textures. After that the marker position gets updated in real time. I hope it's helpful for you.