Re: Alpha Blending?

• To: Bill Hibbard <billh@xxxxxxxxxxxxx>
• Subject: Re: Alpha Blending?
• From: "Kevin Manross" <kevin.manross@xxxxxxxx>
• Date: Wed, 07 Jan 2004 12:51:20 -0600

Bill Hibbard wrote:

To get continuously varying opacity for blending, you need
to have a ScalarMap to Alpha rather than a ConstantMap. You'll
need to add a RealType to the range values in your Field, and
possibly increase the sampling resolution of your Field in
the direction you want opacity to vary. Please let me know if
that's not clear.

---------------------
| Color1            |
|                   |  ( # -> Color3 )
|                   |
|             -----------------
|             |#####          |
|             |#####          |
|             |#####          |
--------------|               |
              |               |
              |  Color2       |
              -----------------

Here is a snippet of my code:


allBeamsRend = new DefaultRendererJ3D();
allBeamWidthsRend = new DefaultRendererJ3D();
allBeamFillsRend = new DefaultRendererJ3D();
allBeamLabelsRend = new DefaultRendererJ3D();


  public void vcpUpdate() throws VisADException, RemoteException
  {
/*
    rhiDisplay.removeReference(allBeamsRef);
    rhiDisplay.removeReference(allBeamWidthsRef);
    rhiDisplay.removeReference(allBeamFillsRef);
    rhiDisplay.removeReference(allBeamLabelsRef);
*/
    int NUM_ANGLES = beamPath.getNumElevationAngles();
    Gridded2DSet[] paths = beamPath.getBeamPaths();
    UnionSet[] widths = beamPath.getBeamWidths();
    Irregular2DSet[] fills = beamPath.getBeamFills();
    Tuple[] labels = beamPath.getBeamLabels();

    allBeamsRef = new DataReferenceImpl[NUM_ANGLES];
    allBeamWidthsRef = new DataReferenceImpl[NUM_ANGLES];
    allBeamFillsRef = new DataReferenceImpl[NUM_ANGLES];
    allBeamLabelsRef = new DataReferenceImpl[NUM_ANGLES];
    ConstantMap[][] widthMap = new ConstantMap[NUM_ANGLES][];
    ConstantMap[][] fillMap = new ConstantMap[NUM_ANGLES][];

    for (int i = 0; i < NUM_ANGLES; i++)
    {
      widthMap[i] = new ConstantMap[]{
        new ConstantMap(1.0f, Display.Red),
        new ConstantMap(1.0f, Display.Green),
        new ConstantMap(( (float)(i*(1/NUM_ANGLES)) ), Display.Blue),

      fillMap[i] = new ConstantMap[]{
        new ConstantMap(1.0f, Display.Red),
        new ConstantMap(1.0f, Display.Green),
        new ConstantMap(( (float)(i*(1/NUM_ANGLES)) ), Display.Blue),
        new ConstantMap(0.75f, Display.Alpha)};

      allBeamsRef[i] = new DataReferenceImpl("allBeamsRef" + i);
      allBeamWidthsRef[i] = new DataReferenceImpl("allBeamsRef" + i);
      allBeamFillsRef[i] = new DataReferenceImpl("allBeamsRef" + i);
      allBeamLabelsRef[i] = new DataReferenceImpl("allBeamsRef" + i);

      allBeamsRef[i].setData( paths[i] );
      allBeamWidthsRef[i].setData( widths[i] );
      allBeamFillsRef[i].setData( fills[i] );
      allBeamLabelsRef[i].setData( labels[i] );
    }

    rhiDisplay.addReferences(allBeamsRend, allBeamsRef);

    rhiDisplay.addReferences(allBeamFillsRend, allBeamFillsRef, fillMap);
    rhiDisplay.addReferences(allBeamLabelsRend, allBeamLabelsRef);


  }


I get the following runtime error:

and the line number is associated with:

rhiDisplay.addReferences(allBeamsRend, allBeamsRef);


Thanks for any help you can provide!

-kevin.


--
+------------------------------------------------------------+
Kevin L. Manross        [KD5MYD] <><          (405)-366-0557
CIMMS Research Associate               kevin.manross@xxxxxxxx
[NSSL-WRDD/SWATN]           http://www.cimms.ou.edu/~kmanross

"My opinions are my own and not representative of CIMMS, NSSL,
 NOAA or any affiliates"
+------------------------------------------------------------+

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    • From: Bill Hibbard