SharpDX colored PointCloud

Question

I am using SharpDX to render a point cloud, using the following code:

PointsModel = new PointGeometryModel3D();
PointsModel.Geometry = new PointGeometry3D();

//create positions
PointsModel.Geometry.Positions = new Vector3Collection();
PointsModel.Geometry.Positions.AddRange(
            new SharpDX.Vector3[]
            { 
              new SharpDX.Vector3(0,0,0),
              new SharpDX.Vector3(10,0,0),
              new SharpDX.Vector3(0,10,0),
              new SharpDX.Vector3(0,0,10),
            });

//create colors
PointsModel.Geometry.Colors = new Color4Collection();
PointsModel.Geometry.Colors.AddRange(
            new SharpDX.Color4[]
            {
              new SharpDX.Color4(1f,0,0,1),
              new SharpDX.Color4(1f,0,0,1),
              new SharpDX.Color4(1f,0,0,1),
              new SharpDX.Color4(1f,0,0,1)
            });

//create indices
PointsModel.Geometry.Indices = new IntCollection();
PointsModel.Geometry.Indices.AddRange(
            new int[]
            {
              0,
              1,
              2,
              3
            });

 PointsModel.Figure = PointFigure.Rect;
 PointsModel.Size=new Size(10, 10);

And in the view:

<hx:Viewport3DX EffectsManager="{Binding EffectsManager1}" 
                Camera="{Binding Camera1}" BackgroundColor="#FF88AACD" 
                ZoomExtentsWhenLoaded="True">
    <hx:AmbientLight3D Color="#030303" />
    <hx:DirectionalLight3D Direction="{Binding Camera.LookDirection}" Color="White" />
    <hx:PointGeometryModel3D  Geometry="{Binding PointsModel.Geometry}" Size="{Binding PointsModel.Size}" Figure="{Binding PointsModel.Figure}">          
    </hx:PointGeometryModel3D>
  </hx:Viewport3DX>

I want the points to have individual colors, but I don't even get them to be red. No matter how I set the color values in the colors list, the points are always rendered black. What am I missing?

Answer 1

I solved it by setting the color in the PointGeometryModel3D to a static value:

<hx:Viewport3DX EffectsManager="{Binding EffectsManager1}" 
            Camera="{Binding Camera1}" BackgroundColor="#FF88AACD" 
            ZoomExtentsWhenLoaded="True">
  <hx:AmbientLight3D Color="#030303" />
  <hx:DirectionalLight3D Direction="{Binding Camera.LookDirection}" Color="White" />
  <hx:PointGeometryModel3D  Geometry="{Binding PointsModel.Geometry}" 
      Size="{Binding PointsModel.Size}" 
      Figure="{Binding PointsModel.Figure}" 
      Color="{x:Static Colors.White}">          
  </hx:PointGeometryModel3D>
</hx:Viewport3DX>

But I don't understand why this is necessary.

The point cloud is now rendered correctly including the individual colors per point.