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Light problem in Helix Sharp DX

Amit Pathak 3 years ago in Question • updated 3 years ago 1


I am trying to build an obj file viewer using Helix Toolkit with SharpDX. So far I am able to load an object file and render it's contents to Helix Viewport3DX. Model looks good with some obj files but for others there are some lightning problem and back surfaces are always black. I am not sure what am I doing wrong. Is this light problem due to the fact that SharpDX does not support back materials??

Problem using Helix Sharp DX:

Original model looks like this in Adobe DC Reader:

Viewport3DX settings are:


<DataTemplate x:Key="Template1">
<hx:MyMeshGeometryModel3D Geometry="{Binding Geometry}" Transform="{Binding Transform}" Material="{Binding Material}"/>
<hx:RenderTechniqueConverter x:Key="RenderTechniqueConverter"/></Window.Resources>

<hx:Viewport3DX x:Name="helixViewport"

Camera="{Binding Camera}" CameraRotationMode="Trackball"
RenderTechnique="{Binding RenderTechnique}"
RenderTechniquesManager="{Binding RenderTechniquesManager}"
EffectsManager="{Binding EffectsManager}"
BackgroundColor="{Binding BackgroundColor}"
<MouseBinding Gesture="LeftClick" Command="hx:ViewportCommands.Rotate"/>
<MouseBinding Gesture="MiddleClick" Command="hx:ViewportCommands.Zoom"/>
<MouseBinding Gesture="RightClick" Command="hx:ViewportCommands.Pan"/>
<hx:AmbientLight3D Color="{Binding AmbientLightColor}"/>
<hx:DirectionalLight3D Color="{Binding DirectionalLightColor1}" Direction="-1,-1,-1"/>
<hx:DirectionalLight3D Color="{Binding DirectionalLightColor2}" Direction="1,-1,-0.1"/>
<hx:DirectionalLight3D Color="{Binding DirectionalLightColor3}" Direction="0.1,1,-1"/>
<hx:DirectionalLight3D Color="{Binding DirectionalLightColor4}" Direction="0.1,0.1,1"/>
<hx:ItemsModel3D x:Name="itemsModel3d" ItemTemplate="{StaticResource Template1}" ItemsSource="{Binding Items}/">
SharpDX WPF Media3D
Under review

How to get MeshGeometry3D after applying ScaleTransform3D

KotNitro 4 years ago in Question • updated by Øystein Bjørke 4 years ago 1
First of all, many thanks for the great toolkit!
My app is simple STL viewer and it also could transform 3d models and apply cutting planes.
So, I make a trnasform:
model.Transform = new ScaleTransform3D(1, 1, 1 / compression);
How can I get an updated MeshGeometry3D? I need it to call MeshGeometryHelper.Cut()
Thank you!
WPF Media3D

This api was accessed with arguments from the wrong context

Niteen 4 years ago in Question • updated 4 years ago 1

We are adding and removing the ModelVisual3D object using background worker process and we got the the following error message:

Error : "This api was accessed with arguments from the wrong context"

Here is my code:

Private Sub backgroundWorker_ProgressChanged(sender As Object, e As ProgressChangedEventArgs)

Dim list = helixViewport3D.Children.OfType(Of ModelVisual3D).ToList()
For Each item As ModelVisual3D In list
If TypeOf item Is ModelVisual3D AndAlso item.GetName() = "Mesh" Then
End If
Dim visual = CType(e.UserState, ModelVisual3D)
End Sub

We are used the BackgroundWorker thread to update the UI from background process. Can you please suggest how to solve this issue.

Please find the attached screem shot.

Niteen Patil


edit obj

Dihydrogensulfid 3 years ago in Question • updated by Lucas Silva 3 years ago 1


For an extention of my masterthesis, I need to calculate and present flowpaths of an digital surface model.

Therefore I have to questions.

1. i can import an *.obj-file with helix in a viewport with:

var modelImporter = new ModelImporter();
modelImporter.DefaultMaterial = material;
Model3DGroup model3DGroup = new Model3DGroup();
model3DGroup = modelImporter.Load("C:/exampleAreas/Area01.obj");

ModelVisual3D newVisual = new ModelVisual3D { Content = model3DGroup };

MyView.Children.Add(newVisual); // add it to the viewport

but how can I get acess to the geometry of the *.obj to readout the normal-vectors?

2. Is it possible to interact with the positions of the vertices of a loaded *.obj-file?

The hidden agenda is: manipulating the loaded *.obj-file, so the user can modify the height of vertices and change the flowpath.

It would be great if someone could give my a hint or small example :-)

Thanks for reading!


Under review

How to adjust line thickness

Michael Powell 4 years ago in Question • updated 4 years ago 5
...that or potentially some pipes would be better from the calculated points.

The calculations are going well enough, though I'm not precisely sure what the geometric orientations are, given center, converting degrees to radians, and so on. Experimenting for quadrants, once I make the appropriate flips on X/Y, cos/sin, the arch is starting to look like an arch with an increasing number of calculated segments.

Under review

Clickability between oxyplot and helix

pettertho 4 years ago in Question • updated by anonymous 2 years ago 9
Hi all,

Me and a classmate are doing a school assignment where we're asked to develop av visualizing program for tomography data. For parts of this project we are using Helix and Oxyplot. Helix to model the pipes in question with Pipe3D, and Oxyplot to plot an intensity chart for the data set.
The data set is several 2D matrices, one for each measurement. This is processed into a bitmap which is displayed onto the 3D model.

We are using MVVM as our design pattern.

We want to introduce clickability and interactivity between these two parts. When a point or a field is marked with the pointer in the oxyplot, the same area should also be marked on the Helix model, or vice versa. The question is which is the best way to do this, and how does one do it? (bear in mind we are not experienced programmers)

Please feel free to ask any questions!

Programmatic model transform not working

Michael Powell 4 years ago in Question • updated 4 years ago 1
I know that Xaml transforms are working, quite well as a matter of fact. I can ScaleTransform3D about axes to achieve simple mirroring, and it works very well. Such as this, mirrors left/right about the Y plane.
        <ScaleTransform3D ScaleY="-1" />
However, I am trying something similar via code behind, and it doesn't seem to be working quite as well; okay, not at all:
return new RectangleVisual3D
    Origin = new Point3D {X = 10d},
    LengthDirection = new Vector3D {X = 1d},
    Normal = new Vector3D {Z = 1d},
    Transform = new Transform3DGroup
        Children = {new ScaleTransform3D(new Vector3D {X = -1d}),}
My first guess is that perhaps there is some Xaml / Binding magic that is going on behind the scenes. First and a half guess, possibly something about initializing the Transform.Children is causing some problems.

I have also tried initializing RectangleVisual3D.Transform to a new ScaleTransform3D, at first; but then thought that perhaps it needed to be a Transform3DGroup instead, as per some of the example code I've seen listed.

Any other insights would be welcome, however.

Thank you...
WPF Media3D

UIElement Visual3DModel behaves differently than MeshGeometryVisual3D

Domvs Phi 4 years ago in Question • updated 4 years ago 1
Hello. I am testing HelixToolKit and I am trying to achieve a simple task:
Create a revolve object and display it on the 3D view port. Since I need the object to be clickable, I am adding it using the UIElement example (changed it to have the rotation instead of the sphere). This is partially achieved, this is, the object displays and I can click on it (and have a desired event), but the object does not render well as the MeshGeometryVisual3D.

See image. Blue glass was added with UIElement, while the red one with MeshGeometryVisual3D. The red one is ok - it is what I want to obtain, while the blue presents parts transparent. If I rotate the camera those parts turn solid, but others transparent. I do not believe that is a question of light as I tested several. The blue glass is half the size of the red one on propose.
In resume red glass is perfect, blue glass is defected.

Relevant WPF code:

 <h:HelixViewport3D x:Name="view1">
<h:GridLinesVisual3D Center="6 0 -0.5" Fill="Gray" Visible="True"/>
<h:MeshGeometryVisual3D Transform="{h:Translate -5,0,0}" MeshGeometry="{Binding GlassGeometry}" Fill="Red" Visible="True"/>

Demo2Element3D construction (Blue glass):

 public class Demo2Element3D : UIElement3D {
public Demo2Element3D()
var gm = new GeometryModel3D();
var mb = new MeshBuilder();

var profile = new[] { new Point(0, 0), new Point(0, 0.4), new Point(0.06, 0.36), new Point(0.1, 0.1), new Point(0.34, 0.1), new Point(0.4, 0.14), new Point(0.5, 0.5), new Point(0.7, 0.56), new Point(1, 0.46) };
mb.AddRevolvedGeometry(profile, null, new Point3D(0, 0, 0), new Vector3D(0, 0, 1), 200);
gm.Geometry = mb.ToMesh();
gm.Material = Materials.Blue;
Visual3DModel = gm;

Red glass:

 public MeshGeometry3D GlassGeometry {
var builder = new MeshBuilder(true, true);
var profile = new[] { new Point(0 * 2, 0.4 * 2), new Point(0.06 * 2, 0.36 * 2), new Point(0.1 * 2, 0.1 * 2), new Point(0.34 * 2, 0.1 * 2), new Point(0.4 * 2, 0.14 * 2), new Point(0.5 * 2, 0.5 * 2), new Point(0.7 * 2, 0.56 * 2), new Point(1 * 2, 0.46 * 2) };
builder.AddRevolvedGeometry(profile, null, new Point3D(0, 0, 0), new Vector3D(0, 0, 1), 100);
return builder.ToMesh(true);

Any information is helpful as I am very new to Helix and even to WPF.
Thank you

Cutting a mesh with a plane of limited size?

Mehran Maghoumi 4 years ago in Question 0
I know that MeshGeometryHelper has the Cut method that can cut a mesh against a plane.
Obviously, that function uses the traditional math definition of a plane (a plane which has an infinite size).
Is there an easy way to adapt that method to perform a cut using a plane of limited size? In other words, let's say we have the point and the normal of the plane as well as its width and height. How could we cut only a part of the mesh that intersects with this "limited" plane?
Is there a straightforward way of doing this?
Under review

How to render an arch

Michael Powell 4 years ago in Question • updated 4 years ago 2
How would I render an arch, or arc, or semi-circle? Is there a CircleVisual3D element? Possibly a SphereVisual3D with a rectangular cross section? Or a fancy grouping of PipeVisual3D calculated along the geometry of an arc. Of course if I could just render the arc, that would be that.

My math/geometry is a bit rusty, but I can puzzle it out.

Thank you...