Fix #1120 Visualization markers ignore color and show everything as white

[xbroquer]

Description

Fix #1120 Visualization markers ignore color and show everything as white using #752 as base patch

Checklist

• Rendering issues:

  • Attached broken rendering image:

  • Attached fixed rendering image:

• Source code snippet for three cases:

// display marker not using mesh material in transparent blue
marker.color.r = 0;
marker.color.g = 0;
marker.color.b = 1;
marker.color.a = 0.3;
marker.scale.x = 1;
marker.scale.y = 1;
marker.scale.z = 1;
marker.type = visualization_msgs::Marker::MESH_RESOURCE;
marker.mesh_resource = "package://my_pkg/moonwalk.dae";
marker.mesh_use_embedded_materials=false;

// display marker using mesh material and tinted with transparent green
marker.scale.x = 1;
marker.scale.y = 1;
marker.scale.z = 1;
marker.color.r = 0;
marker.color.g = 1;
marker.color.b = 0;
marker.color.a = 0.5f;
marker.type = visualization_msgs::Marker::MESH_RESOURCE;
marker.mesh_resource = "package://my_pkg/moonwalk.dae";
marker.mesh_use_embedded_materials=true;

// display marker using mesh material and not tinted
marker.scale.x = 1;
marker.scale.y = 1;
marker.scale.z = 1;
marker.color.r = 0;
marker.color.g = 0;
marker.color.b = 0;
marker.color.a = 0;
marker.type = visualization_msgs::Marker::MESH_RESOURCE;
marker.mesh_resource = "package://my_pkg/moonwalk.dae";
marker.mesh_use_embedded_materials=true;

[rhaschke]

#752 should already part of the source history. Did you have a look into #893 as well, which seems to revert the first one?

[xbroquer]

Hi Robert,

Thanks for pointing me #893. Seems that this issue has a long story :)

With rviz melodic release, only external image textures (like PR2 base) are displayed. When materials are fully defined inside collada file, the mesh is white.

I also used garaemon/rviz_collada_marker for my tests and added moonwalk marker (that is not using external image files for materials). https://github.com/xbroquer/rviz_collada_marker

The result of rviz melodic release (arrow and moonwalk are white):

When mesh_use_embedded_materials=True, color is not dynamically updated

Here is the result with my latest commit:

Here the 2 videos that shows the dynamic color update:
rviz-melodic-collada-test.zip

However, as you can see, the usage of passes changes the behavior when mesh_use_embedded_materials=True and a color is set.
The material from the mesh cannot be transparent. If we want the marker transparent we have to set mesh_use_embedded_materials=False (third marker).

Do you think this behavior change is acceptable ?

If not, I pushed another solution that does not use passes:
melodic-devel...xbroquer:drx-collada-mesh2

[rhaschke]

I don't think that adding a second pass is the right solution to the problem: It essentially just redraws the mesh with the user-defined color. As you see from the comparison, this doesn't allow to change the transparency of the mesh.
Another option is to use alpha from the user-defined color for both passes, and use the second pass to tint the mesh with the user-defined color as suggested in this PR. However, this will also modify the result for texture-colored meshes.
I think, we need to modify the color "towards" the user-defined one in first place. A single pass will suffice then for drawing. One option is to multiply with the user-defined color.

multiply	current rviz	pull request

[rhaschke]

Closing in favor of #1424. @xbroquer, could you please review the new PR?