Re: Specific alpha values

• To: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>, VisAD List <visad-list@xxxxxxxxxxxxx>
• Subject: Re: Specific alpha values
• From: Andrew Donaldson <A.Donaldson@xxxxxxxxxx>
• Date: Wed, 23 May 2001 17:39:36 +1000

> You can do it with a ScalarMap to Display.RGBA. The
> getControl() method for this ScalarMap will return a
> ColorAlphaControl, and you can call its setTable() method
> to set the 4-component lookup table for red, green, blue
> and alpha. See Sections 4.6 and 4.11 of the tutorial for
> more details.

Hey, that was really obvious now that you point it out!
Thanks guys.  It's not working at the moment, I can certainly
change the colours, but the alpha doesn't change.  Is it something
to do with me using ImageRendererJ3D?

My code is:
                // Add a scalarMap to map the samples to RGBA
                ScalarMap range2D = new ScalarMap(
                                (RealType)rtype.getComponent(0),
                                Display.RGBA);
                display.addMap(range2D);

                // Create a RGBA lookup table
                final int dataDepth = 16;
                myColorTable = new float[4][dataDepth];
                for(int i=0; i<dataDepth; i++) {
                        myColorTable[0][i]= (float)0;   // red
                        myColorTable[1][i]= (float)0;   // green
                        myColorTable[2][i]= (float)i;   // blue
                        myColorTable[3][i]= (float)i;   // alpha
                }
                // This does change the background to grey
                myColorTable[0][0]= (float)0.5;
                myColorTable[1][0]= (float)0.5;
                myColorTable[2][0]= (float)0.5;
                myColorTable[3][0]= (float)0.5;

//              ColorControl control
(ColorControl)range2D.getControl();
//              control.initGreyWedge();
//              control.initVis5D();
                ColorAlphaControl control
                        (ColorAlphaControl)range2D.getControl();
                control.setTable(myColorTable);

thanks again,

Andrew.

-- 
 Andrew Donaldson                                           
 Email:   A.Donaldson@xxxxxxxxxx                Bureau of Meteorology
 Phone:   +61 3 9669 4537            P.O. Box. 1289K/150 Lonsdale St,
 Fax:     +61 3 9669 4128                       Melbourne, Australia.

• Follow-Ups:
  • Re: Specific alpha values
    • From: Tom Whittaker

• References:
  • Specific alpha values
    • From: Andrew Donaldson
  • Re: Specific alpha values
    • From: Bill Hibbard