Clipping with orthographic camera in HelixViewport3D

Hi, I’ve been using the HelixViewPort3D with a perspective camera and it worked really well, but lately I had to change the camera to an orthographic one.

When using the HelixViewPort3D with an orthographic camera (Orthographic Property set to true), the 3D model is clipping as you can see on the bottom right picture below. It’s like the view is based on the perspective mode and only shows what is visible with a perspective camera even though it uses an orthographic camera.

View of the entire 3D model

Perspective view (Orthographic = False) & Orthographic view (Orthographic = True)

Used code to generate pictures above (toggling Orthographic to True/False)

<Window x:Class="HelixToolkitTest.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:helix="http://helix-toolkit.org/wpf"
    Title="MainWindow" Height="350" Width="525">
    <helix:HelixViewport3D Background="White" Orthographic="True">
        <helix:CoordinateSystemVisual3D/>
    <ModelVisual3D>
        <ModelVisual3D.Content>
            <DirectionalLight Color="#FFFFFF" Direction="-0.612372,-0.5,-0.612372" />
        </ModelVisual3D.Content>
    </ModelVisual3D>
    <ModelVisual3D>
        <ModelVisual3D.Content>
            <GeometryModel3D>

                <GeometryModel3D.Geometry>
                    <MeshGeometry3D
                 TriangleIndices="0,1,2 3,4,5 "
                 Normals="0,0,1 0,0,1 0,0,1 0,0,1 0,0,1 0,0,1 "
                 TextureCoordinates="0,0 1,0 1,1 1,1 0,1 0,0 "
                 Positions="-0.5,-0.5,0.5 0.5,-0.5,0.5 0.5,0.5,0.5 0.5,0.5,0.5 -0.5,0.5,0.5 -0.5,-0.5,0.5 " />
                </GeometryModel3D.Geometry>

                <GeometryModel3D.Material>
                    <MaterialGroup>
                        <DiffuseMaterial>
                            <DiffuseMaterial.Brush>
                                <LinearGradientBrush StartPoint="0,0.5" EndPoint="1,0.5">
                                    <LinearGradientBrush.GradientStops>
                                        <GradientStop Color="Yellow" Offset="0" />
                                        <GradientStop Color="Red" Offset="0.25" />
                                        <GradientStop Color="Blue" Offset="0.75" />
                                        <GradientStop Color="LimeGreen" Offset="1" />
                                    </LinearGradientBrush.GradientStops>
                                </LinearGradientBrush>
                            </DiffuseMaterial.Brush>
                        </DiffuseMaterial>
                    </MaterialGroup>
                </GeometryModel3D.Material>

                <GeometryModel3D.Transform>
                    <ScaleTransform3D ScaleX="50" ScaleY="1" ScaleZ="1"/>
                </GeometryModel3D.Transform>
            </GeometryModel3D>
        </ModelVisual3D.Content>
    </ModelVisual3D>
</helix:HelixViewport3D>

</Window>

Any idea on how to resolve this problem?

Thanks,

[MoSkinny]

Unless there is another side effect that I haven’t discovered yet. I think I was just able to get it to work. As my comment said above when I use -Infinity and Infinity something happens and we get some NaN values. So next I tried to use Double.MinValue (-1.7976931348623157E+308) and Double.MaxValue (1.7976931348623157E+308). These values did not produce any NaN values but the ViewPort still refeused to Pan. …so I kept stepping the values down until the following value didn’t produce the clipping effect but still allowed me to Pan. Hopefully that helps someone else or leads to a permanente fix.

<Helix:HelixViewport3D.Camera>
    <OrthographicCamera NearPlaneDistance="-1.7976931348623157E+8" FarPlaneDistance="1.7976931348623157E+8" />
</Helix:HelixViewport3D.Camera>'

[miloush]

@dmackersie OrthographicCamera.NearPlaneDistance=-Infinity is a valid scenario. The fact that the model completely disappears when trying to pan (but not rotate, same for 0) feels like a bug. Why would panning an orthographic camera need to rely on NearPlaneDistance?

The other problem is that while setting <= 0 near plane on a perspective camera makes terrible things happen, it is happily copied over from an orthographic DefaultCamera. I would suggest that on reset of/switch to perspective camera, the NearPlaneDistance is copied from a default orthographic camera only if > 0. The CameraHelper.Copy method already allows to not copy planes, so perhaps this could be used when the default camera does not match the target camera. Alternatively, there could be separate default orthographic and default perspective camera.