Re: [gl4java-usergroup] need help!!

[Montana, P. M <pat...@lm...>]

Philippe,=20

Here is some code that we use for tessellating polygons. I'm not 100% =
sure
we did it correctly, but it does seem to work OK. When I have more than =
one
GL4Java display in the same application, I'll sometimes get a native =
error
outside the JVM related to the tesselation callbacks. But I don't know =
if
I'm doing something wrong, or it is a library bug. (BTW, the 'Triplet' =
class
below is just a simple class we wrote to hold an x,y,z.)=20


-Mark=20


private void  tesselatePolygon( GLFunc gl_, GLUFunc glu_ )=20
{=20
   int      size     =3D pointList.size();=20
   Triplet  point    =3D null;=20
   double   coords[] =3D new double[3];=20


   long     polyTess =3D createTesselator( gl_, glu_ );=20


   glu_.gluTessBeginPolygon( polyTess, (double[]) null );=20
      glu_.gluTessBeginContour( polyTess );=20


         for( int ii=3D0; ii<size; ii++ )=20
         {=20
            point =3D (Triplet) pointList.get( ii );=20


            coords[0] =3D point.getX();=20
            coords[1] =3D point.getY();=20
            coords[2] =3D 0.0;=20


            double  tmpData[] =3D new double[2];=20
            tmpData[0] =3D coords[0];=20
            tmpData[1] =3D coords[1];=20


            glu_.gluTessVertex( polyTess, coords, tmpData );=20
         }=20


      glu_.gluTessEndContour( polyTess );=20
   glu_.gluTessEndPolygon( polyTess );=20


   glu_.gluDeleteTess( polyTess );=20


   // Here is where we used to release memory used internally by =
tesselator=20
   // in Magician=20
}=20
 =20


private long  createTesselator( GLFunc gl_, GLUFunc glu_ )=20
{=20
   long  polyTess =3D glu_.gluNewTess();=20


   glu_.gluTessCallback( polyTess, glu_.GLU_TESS_BEGIN, gl_,=20
                         "glBegin", "(I)V", 0, 0, 0, 0, 0 );=20
   glu_.gluTessCallback( polyTess, glu_.GLU_TESS_VERTEX, gl_,=20
                         "glVertex2dv", "([D)V", 2, 0, 0, 0, 0 );=20
   glu_.gluTessCallback( polyTess, glu_.GLU_TESS_END, gl_,=20
                         "glEnd", "()V", 0, 0, 0, 0, 0 );=20
   glu_.gluTessCallback( polyTess, glu_.GLU_TESS_ERROR, this,=20
                         "error_callback", "(I)V", 0, 0, 0, 0, 0 );=20
   glu_.gluTessCallback( polyTess, glu_.GLU_TESS_COMBINE, this,=20
                         "combine_callback", "([D[D[D[D)V", 2, 0, 0, 2, =
0 );



   glu_.gluTessProperty( polyTess, GLUEnum.GLU_TESS_WINDING_RULE,=20
                                   GLUEnum.GLU_TESS_WINDING_ODD );=20


   return( polyTess );=20
}=20
 =20


public void  error_callback( int error )=20
{=20
   System.err.println( "PolygonPrimitive2d.error_callback() - "=20
                     + "tesselation error was generated: " + error );=20
   System.err.flush();=20
}=20
 =20


public void  combine_callback( double[] coords, double[] vertexData,=20
                               double[] weights, double[] data )=20
{=20
   data[0] =3D coords[0];=20
   data[1] =3D coords[1];=20
}=20
 =20
 =20


armand darman wrote:=20


hi,=20


I need to tessellate concav polygons with GL4java.=20


But GL4java functions (like gluTessCallBack for=20
instance)don't have the same parameters than OpenGL=20
ones.=20


Where could I find, or could you give me a whole=20
description of those functions in GL4java?=20


Thank you very much!!=20


from: Philippe, student.=20
 =20


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