| Fast Inaccurate Transparency
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Info & Tags |
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| Article #: |
1 |
| Created: |
2009-12-14 |
| Modified: |
2010-06-03 |
| Tags: |
eyeshot3, transparency |
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Accurate transparency can be too slow for huge semi-transparent meshes or when thousands of simple semi-transparent entities come into play. If this is your case, give a try to the following approach.
- Set display mode as Rendered
- Entities are drawn in the same order they are added, therefore keep the semi-transparent ones at the end of the Viewport.Entities collection and on the same layer
- Never set the material Diffuse.A less than 255 otherwise the accurate transparency algorithm will process the entity
- Subclass the necessary entity types (Mesh, StlModel, etc.) and override the Render() method
- Add the following function body:
| C# |
Material mat = new Material("Glass", Color.FromArgb(100, Color.Cyan));
public override void Render(float screenToWorld,
float[] pattern, Dictionary‹char, CharData› charDefs)
{
gl.Enable(gl.BLEND);
Viewport.SetColorRendered(this, mat, Selected);
byte cullingEnabled = gl.IsEnabled(gl.CULL_FACE);
if (cullingEnabled == 0)
gl.Enable(gl.CULL_FACE);
gl.FrontFace(gl.CW);
base.Render();
gl.FrontFace(gl.CCW);
base.Render();
if (cullingEnabled == 0)
gl.Disable(gl.CULL_FACE);
gl.Disable(gl.BLEND);
}
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| Visual Basic |
Dim mat As New Material("Glass", Color.FromArgb(100, Color.Cyan))
Public Overridable Sub Render(ByVal screenToWorld As Single, _
ByVal pattern As Single(), _
ByVal charDefs As Dictionary(Of Char, CharData))
gl.Enable(gl.BLEND)
Viewport.SetColorRendered(Me, mat, Selected)
Dim cullingEnabled As Byte = gl.IsEnabled(gl.CULL_FACE)
If cullingEnabled = 0 Then
gl.Enable(gl.CULL_FACE)
End If
gl.FrontFace(gl.CW)
MyBase.Render()
gl.FrontFace(gl.CCW)
MyBase.Render()
If cullingEnabled = 0 Then
gl.Disable(gl.CULL_FACE)
End If
gl.Disable(gl.BLEND)
End Sub |
This method will draw the entity twice: the first time back-facing triangles only while the second front-facing only. This is the fastest - inaccurate - way to draw a semi-transparent entity in Eyeshot 3.x.
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