Nick,
while sending my reply, I saw that those traingle were messed up.
Still I hope you got the idea. If not, please let me know.
Dirk
----- Original Message -----
From: "Nick Stark" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, June 09, 2003 10:53 PM
Subject: Re: [JAVA3D] Inverted Normals Question
> Thanks for your response, Alessandro.
>
> I am actually mirroring a coordinate system change transform. Here is one
> of the transforms I am trying to mirror.
> 0.997564, -0.069755, -0.000462, -0.000000,
> 0.067070, 0.957300, 0.281208, -0.006913,
> -0.019174, -0.280554, 0.959647, -0.04314,
> 0.000000, 0.000000, 0.000000, 1.000000
>
> And I multiplied this transform by the following (a scale of -1.0 applied
> to the x coordinates):
> -1.0, 0.0, 0.0, 0.0,
> 0.0, 1.0, 0.0, 0.0,
> 0.0, 0.0, 1.0, 0.0,
> 0.0, 0.0, 0.0, 1.0
>
> I'm not applying this transform to a shape, though...it is a bit more
> complex. To summarize, I need to mirror a coordinate system change
> (similar to one shown above), and use this transform in a series of
> transforms that are multiplied together. The product of this series of
> transforms is then used to transform a shape. Any ideas on how to mirror
> the transform without screwing up the normals?
>
> Thanks for your help,
> Nick
>
>
>
>
>
> Maybe this is a bug.
> How do you do this mirroring ??
> transform3D.setScale(-1) ? ( I guess the Java3D develop. team never
> imagined a negative scaling hehehehe )
> If so, may you can try another way as reverting X axis of the shapes, as
> below :
>
> private void mirrorShapeXAxis(Shape3D sh)
> {
> Appearance app = sh.getAppearance();
> if (app != null)
> {
> PolygonAttributes polyA = new PolygonAttributes();
> polyA.setCullFace(polyA.CULL_FRONT);
> app.setPolygonAttributes(polyA);
> }
>
> GeometryInfo gi = new GeometryInfo((GeometryArray)sh.getGeometry());
> Point3f[] coords = gi.getCoordinates();
>
> // mirror in X axis
> for(int i=0; i<coords.length;i++)
> {
> coords[i].x = - coords[i].x;
> }
> gi.setCoordinates(coords);
> // it reverse the normals - not mirror like
> //NormalGenerator ng = new NormalGenerator();
> //ng.generateNormals(gi);
> //gi.recomputeIndices();
>
> sh.setGeometry(gi.getGeometryArray());
> }
>
>
> Please report if it works or not.
>
> Alessandro
>
>
>
>
> ----- Original Message -----
> From: "Nick Stark" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Monday, June 09, 2003 10:09 AM
> Subject: [JAVA3D] Inverted Normals Question
>
> > Hi -
> >
> > I have a set of objects, all of whose normals are initially correct (all
> > lighting looks as it should).
> >
> > However, I apply a mirror transform to some of the objects, and when
> > viewing the new objects, it appears that the normals have been inverted
> on
> > the geometry. The lights still look correct for the objects that were
> not
> > mirrored, but the objects that are mirrored have dark faces and bright
> > backsides. The objects have not moved to such a position where this
> should
> > be the case, though. Is there some issue with the 3D API or is this a
> > problem that any of you have encountered before?
> >
> > Thanks for any help.
> >
> > Nick
> >
> >
>
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>
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