The capability bits I included below allow you to REPLACE the  
transparency object of the appearance, but not MODIFY that  
transparency object.  Hence #1 won't work.

You could probably get #1 working with adding something like this to  
the constructor:

TransparencyAttributes ta = appearance.getTransparencyAttributes();
ta.setCapability(TransparencyAttributes.ALLOW_VALUE_READ);
ta.setCapability(TransparencyAttributes.ALLOW_VALUE_WRITE);
ta.setCapabilityIsFrequent(TransparencyAttributes.ALLOW_VALUE_READ);
ta.setCapabilityIsFrequent(TransparencyAttributes.ALLOW_VALUE_WRITE);

Sean

On Nov 15, 2006, at 6:58 AM, Michael Lees wrote:

> Hi Sean (and Bruno)
>
> Thanks for the replies.
>
> First of, let me say I've tried 3 different ways of changing the  
> transparency.
>
> From my previous mail....
> >> public sim.portrayal3d.simple.CubePortrayal3D representation;
> >> representation = new sim.portrayal3d.simple.CubePortrayal3D 
> (colour,size)
>
> The 3 different ways...
> 1. - Modifying transparency component directly
> representation.appearance.getTransparencyAttributes 
> ().setTransparency(trans);
>
> 2. - Creating a new colour with new alpha value
> java.awt.Color colour2 = new java.awt.Color(colour.getRed(),  
> colour.getGreen(), colour.getBlue(), (int)Math.round(trans*255));
> representation.appearance = CubePortrayal3D.appearanceForColor 
> (colour2);
>
> 3. - Creating a new transparency attribute object
> representation.appearance.setTransparencyAttributes(new  
> TransparencyAttributes(TransparencyAttributes.BLENDED, trans));
>
> First off, 2 works without any modification to MASON
>
> I tried as Sean suggested and...
> 3 now works.
>
> However, 1 still does not work, exception given:
>
> javax.media.j3d.CapabilityNotSetException: Transparency: no  
> capability to set component
>
>
> Sorry, I appreciate this is probably a java3d question and thanks  
> again for you help.
>
> Is there a right way to do this?
>
> Thanks
>
> -Mike
>
> Sean Luke wrote:
>> Michael, you don't want to replace the appearance of an object.   
>> That's what Shape3D.ALLOW_APPEARANCE_WRITE does.  What you want to  
>> do is be able to do is change the Appearance's attributes itself,  
>> something like this:
>>     public CubePortrayal3D(Appearance appearance, boolean  
>> generateNormals,
>>     boolean generateTextureCoordinates, float scale)
>>         {
>>         this.generateNormals = generateNormals;
>>         this.generateTextureCoordinates = generateTextureCoordinates;
>>         this.appearance = appearance;
>>     // changed here
>>     appearance.setCapability 
>> (Appearance.ALLOW_TRANSPARENCY_ATTRIBUTES_READ);      
>> appearance.clearCapabilityIsFrequent 
>> (Appearance.ALLOW_TRANSPARENCY_ATTRIBUTES_READ);      
>> appearance.setCapability 
>> (Appearance.ALLOW_TRANSPARENCY_ATTRIBUTES_WRITE);      
>> appearance.clearCapabilityIsFrequent 
>> (Appearance.ALLOW_TRANSPARENCY_ATTRIBUTES_WRITE);          
>> this.scale = scale;
>>         for(int i=0;i<scaledVerts.length;i++)
>>             scaledVerts[i] = verts[i]*scale;
>>         }
>> But that might not work, because when the portrayal creates the  
>> scene object, assigning it the Appearance, Java3D may *copy* the  
>> appearance, and so changing the appearance later on doesn't change  
>> the copy that's being used.  You'll have to see for yourself to  
>> determine this.  If it's the case that it doesn't work, then I  
>> have some other ideas.
>> Sean
>> On Nov 14, 2006, at 9:41 AM, Michael Lees wrote:
>>> Hi,
>>>
>>> I'm trying to vary the transparency of a cube during the  
>>> simulation execution.
>>>
>>> I define the following....
>>>
>>> public sim.portrayal3d.simple.CubePortrayal3D representation;
>>> representation = new sim.portrayal3d.simple.CubePortrayal3D 
>>> (colour,size)
>>>
>>>
>>> And then attempt to change the transparency by...
>>>
>>> representation.appearance.getTransparencyAttributes 
>>> ().setTransparency(1.0f);
>>>
>>>
>>> I noticed that nothing was appearing, looked like the cubes had 0  
>>> transparency.
>>>
>>> Surrounding the setTransparency call with a try catch I realised  
>>> the follow exception was being thrown...
>>>
>>> javax.media.j3d.CapabilityNotSetException: Appearance: no  
>>> capability to get transparencyAttributes
>>>
>>>
>>> Looking into CubePortrayal3D.getModel I found the following...
>>>
>>> 131: Shape3D localShape = new Shape3D(quadArray,appearance);
>>> 132: localShape.setCapability(Shape3D.ALLOW_APPEARANCE_WRITE);
>>>
>>> Which should allow you to change the appearance properties of the  
>>> Shape3D.
>>>
>>> However, is the problem that I'm calling getTransparencyAttributes 
>>> () when localShape.setCapability(Shape3D.ALLOW_APPEARANCE_READ);  
>>> has not been set?
>>>
>>> Or I'm I going about this all the wrong way? How should I change  
>>> the transparency of a CubePortrayal3D (or more generally any  
>>> Portrayal3D).
>>>
>>> Thanks
>>>
>>> --Michael Lees
>>>
>>>
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