Re: [gl4java-usergroup] glu tesselator

[Jean-Yves B. <jea...@wa...>]

Hello Olivier,

I also got some crash problem with tesselation. Particularly with ERROR and COMBINE callbacks.

I noticed usually, the reason was the callback declaration format and
function signature parameters. I also tried several combination.
You may try the following:

// Call back declaration
// ------------------------

    gluFunc.gluTessCallback( tesselator, gluFunc.GLU_TESS_VERTEX, this, "vertexCallback", "([D)V",
6, 0, 0, 0, 0);
    gluFunc.gluTessCallback( tesselator, gluFunc.GLU_TESS_BEGIN, this, "beginCallback", "(I)V", 0,
0, 0, 0, 0);
    gluFunc.gluTessCallback( tesselator, gluFunc.GLU_TESS_END, this, "endCallback", "()V", 0, 0,
0, 0, 0);
    /*gluFunc.gluTessCallback( tesselator, gluFunc.GLU_TESS_ERROR, this, "errorCallback", "(I)V",
0, 0, 0, 0, 0);  >> CRASH*/
    gluFunc.gluTessCallback( tesselator, gluFunc.GLU_TESS_COMBINE, this, "combineCallback",
"([D[D[F[D)V", 3, 4*6, 4, 6, 0);

// Call back implementation
//------------------------------
 public void beginCallback(int which)
 {    ....    }

public void vertexCallback(double[/*6*/] vertex)
 {
  double[] col = new double[3];
  System.arraycopy(vertex, 0, col, 0, 3);    >> Differ from you code.
    ....
 }

 public void errorCallback(int errorCode)
 {
  throw(new Exception("...."));
 }

 public void endCallback()
 {    ....    }

 public void combineCallback(double coords[/*3*/], double vertex_data[/*4x6*/], float
weight[/*4*/], double[/*6*/] dataOut )
{
  throw(new Exception("...."));
 }

I fact, the gl4java implementation for tesselation is not very clear to me.

Last minute remark about your code:
In your END call back declaration, you put a "glBegin" String! Are you it is what you want ?
glu.gluTessCallback(tesselator,GLU_TESS_END,gl,"glBegin","()V",0,0,0,0,0);

Bye.

Olivier Michel a *crit :

> Hello,
>
> I am experiencing a crash in the native
> gl4java.GLUFuncJauJNI.gluTessEndPolygon method (I guess it's a crash of
> the native gluTessEndPolygon function) while translating a C++ source to
> Java. The problem is that the C++ source do work perfectly while the
> Java one crashes. So I wonder I understood properly the Java
> gluTesselator principles... Note that I use the GLU from SGI sample
> implementation because the one provided with Mesa is buggy (this might
> also be the source of the problem is Sven assumes we use MesaGLU...).
>
> Here is a sample of my source code which seems correct to my eyes: (see
> below)
>
> I tryed many things to get cues about what's happening in the code,
> without success. Thanks for help!
>
> -Olivier
>
> import gl4java.GLFunc;
> import gl4java.GLUFunc;
> import gl4java.GLEnum;
> import gl4java.GLUEnum;
>
> public class GlRenderer implements GLEnum, GLUEnum {
>   GLFunc gl;
>   GLUFunc glu;
>   int tesselator=0;
>   static public void init(GLFunc glFunc,GLUFunc gluFunc) {
>     r.gl = glFunc;
>     r.glu = gluFunc;
>     tesselator = glu.gluNewTess();
>
> glu.gluTessCallback(tesselator,GLU_TESS_BEGIN,gl,"glBegin","(I)V",0,0,0,0,0);
>
> glu.gluTessCallback(tesselator,GLU_TESS_VERTEX,this,"gluTessVertex","([D)V",6,0,0,0,0);
>
> glu.gluTessCallback(tesselator,GLU_TESS_END,gl,"glBegin","()V",0,0,0,0,0);
>
> glu.gluTessCallback(tesselator,GLU_TESS_ERROR,this,"gluError","(I)V",0,0,0,0,0);
>
> glu.gluTessCallback(tesselator,GLU_TESS_COMBINE,this,"gluTessCombine","([D[D[F[D)V",3,4,4,6,0);
>
>   }
>   void glError() {
>     int e = gl.glGetError();
>     System.err.println(glu.gluErrorString(e));
>   }
>   void gluError(int e) {
>     System.err.println(glu.gluErrorString(e));
>   }
>   void gluTessCombine(double coords[/*3*/],double
> vertex_data[/*4*/],float weight[/*4*/],double[/*6*/] dataOut) {
>     // just do nothing
>     System.out.println("Combine");
>   }
>   void gluTessVertex(double[/*6*/] vertex) {
>     System.out.println("gluTessVertex");
>     double [] normal = new double[3];
>     System.arraycopy(vertex,3,normal,0,3);
>     gl.glNormal3dv(normal);
>     gl.glVertex3dv(vertex);
>   }
>   void drawFace(double [/*n*/][/*6*/] point,boolean convex,boolean ccw)
> {
>     int n = point.length;
>     System.out.println("There are "+n+" points:");
>     for(int i=0;i<n;i++) { for(int j=0;j<6;j++)
> System.out.print(point[i][j]+" "); System.out.println(); }
>     System.out.println("tesselator = "+tesselator);
>
>     if (convex) {
>       switch(n) {
>         case 0:
>         case 1:
>         case 2:  return;
>         case 3:  gl.glBegin(GL_TRIANGLES); break;
>         case 4:  gl.glBegin(GL_QUADS); break;
>         default: gl.glBegin(GL_POLYGON); break;
>       }
>       for(int i=0;i<n;i++) {
>         gl.glNormal3d(point[i][3],point[i][4],point[i][5]);
>         gl.glVertex3d(point[i][0],point[i][1],point[i][2]);
>       }
>       gl.glEnd();
>     } else {
>
> glu.gluTessProperty(tesselator,GLU_TESS_WINDING_RULE,GLU_TESS_WINDING_POSITIVE);
>
>       glu.gluTessBeginPolygon(tesselator,(double [])null);
>       glu.gluTessBeginContour(tesselator);
>       for(int i=0;i<n;i++)
> glu.gluTessVertex(tesselator,point[i],point[i]);
>       glu.gluTessEndContour(tesselator);
>       glu.gluTessEndPolygon(tesselator);
>     }
>   }
> }
>
> _______________________________________________
> gl4java-usergroup mailing list
> gl4...@li...
> http://lists.sourceforge.net/mailman/listinfo/gl4java-usergroup

--
--------------------------------------
Jean-Yves BRUD
POLYQUARK - Ingenierie & Creation 3D
Palahou - 31330 LARRA    France
Tel: 05.62.79.03.33  Fax: 05.62.79.03.38
Mail: jea...@wa...
--------------------------------------