SceneNode mesh created from scratch has no color/gray color

[Tyronnosaurus 7]

Hello guys. Some time ago I made a little Python application to visualize the results of a FEM study, and now I'm integrating it into a Cura plugin. However, the resulting SceneNode's mesh looks completely gray/colorless:

 

 

The steps followed to prepare the mesh are:

1) Calculate the coordinates and color of every square. The algorithm is pretty much the same as in the old application so I didn't change much.

2) Create a SceneNode object. Make it a child of the Root SceneNode.

3) Use addQuad() to actually build the mesh by drawing each little square. More or less like this:

class ResultsNode(SceneNode):
  
  [...]
  
  def buildMesh(self, geometryData):

      self.mb = MeshBuilder()
      self.resultsMeshBuilder(geometryData)
      mesh = self.mb.build()
      self.setMeshData(mesh)

  def resultsMeshBuilder(self, geometryData):

      [...] #Code to find coordinates P1, P2, P3, P4 and color of each square

      color = Color(1.0, 0, 0, 1.0)	#For now, just paint all squares RED
      for face in ListOfFaces:
          self.mb.addQuad(face.P1, face.P2, face.P3, face.P4, color)

 

Geometrically, the mesh is built correctly (I've successfully tested other shapes). It's just the color that fails.

If the code above is not the culprit, I suspect it might be the View. Is there somewhere I can learn about views, rendering and shaders (something more in depth than the Uranium docs)? Thanks.

 

  

Edited January 10, 2021 by Tyronnosaurus

[ahoeben 1,852]

The mesh needs to have normals.

[Tyronnosaurus 7]

Thanks, ahoeben. It works now with this change:

 

def buildMesh(self, geometryData):

  self.mb = MeshBuilder()
  self.resultsMeshBuilder(geometryData)
  self.mb.calculateNormals()	#Added this line
  mesh = self.mb.build()
  self.setMeshData(mesh)

  

 

Edited January 12, 2021 by Tyronnosaurus
Added screenshot

[Tyronnosaurus 7]

One additional related question if you don't mind: how would you approach drawing the edges (black lines delimiting each square) like in my first screenshot?

1) With addLine(): I've tried but for some reason the resulting mesh is not drawn correctly when combining addQuad & addLine.

2) Option 1 but putting the lines in a child sceneNode's mesh

3) Some shader or rendering option, if it exists

4) Implementing a custom shader, akin to how the Platform is a single quad but draws a 1x1cm mesh

5) Something else

 

 

Edited January 13, 2021 by Tyronnosaurus

[ahoeben 1,852]

I think applying a custom shader is the best option. Adding lines might work too, but you will end up with LOTs of them for larger organic meshes. You could look at how grid.shader draws lines.

[Tyronnosaurus 7]

[Hey ahoeben, I was just writing a solution I've found, which uses addLine(). Since I've got it almost written I'll just leave it here for anyone curious, but I'll try using a shader as you say]

 

I've discovered that I can simply create a second mesh inside a single SceneNode, and then render each mesh separately. I discovered this by looking into Cura's BuildVolume class. More or less my code is this:

 

1) Create a _grid_mesh and build the wireframe with AddLine()

2) Override the SceneNode.render() method:

    def render(self, renderer):

        if (self.isVisible()):
            #To draw the colored faces -> The most simple rendering
            renderer.queueNode(self)    

            #To draw the edges -> A Lines AKA wireframe rendering
            renderer.queueNode(self, mesh=self._grid_mesh,
                                     mode=RenderBatch.RenderMode.Lines) 
        
        return True

3) Make sure the active view runs this render()

 

I still can't control the lines' color though (always white).

Edited January 13, 2021 by Tyronnosaurus