Hi,

Thanks for helping me figure out the previous question about lighting.

I'm still having trouble giving the back side of polygons a color different from the front side. The same sphere (with fixed lighting!) with half the triangles missing so you can see through can be found.

http://www.geocities.com/bura3no/index.htm

The relevant code is here:

     gl.glMaterialfv(GL.GL_FRONT, GL.GL_AMBIENT_AND_DIFFUSE, Color.GREEN.getComponents(null) );
     gl.glMaterialfv(GL.GL_BACK, GL.GL_AMBIENT_AND_DIFFUSE, Color.RED.getComponents(null) );

     gl.glMaterialfv(GL.GL_FRONT_AND_BACK, GL.GL_EMISSION, Color.BLACK.getComponents(null));

     gl.glMaterialfv(GL.GL_FRONT_AND_BACK, GL.GL_SPECULAR, Color.WHITE.getComponents(null) );
     gl.glPolygonMode(GL.GL_FRONT_AND_BACK, GL.GL_FILL);

     gl.glBegin(GL.GL_TRIANGLES);
     for (int t = 0; t < myMesh.pGetNumberOfElements()/2; t++) {
       Element elem = myMesh.pGetElement(t);
       for (int v = 0; v < elem.pGetNumberOfNodes(); v++) {
         VDouble x = myMesh.pGetX(elem.pGetNode(v));
         VDouble n = normals[elem.pGetNode(v)];
         gl.glNormal3d(n.pGet(0), n.pGet(1), n.pGet(2));
         gl.glVertex3d(x.pGet(0), x.pGet(1), x.pGet(2));
       }
     }
     gl.glEnd();

   }

   gl.glEndList();

Thanks for response.

Your suggestion helped with lighting of the back side (something I did need), but not with the coloring. It's still green rather than some other color.

Need more code.

Try removing gl.glMaterialfv(GL.GL_FRONT, GL.GL_AMBIENT_AND_DIFFUSE, Color.GREEN.getComponents(null) ); and see what happens.  Your code looks fine but obviously something is wrong.

Try reversing your colors, front red, back green.  If everything turns red then we know it isn't your color methods.  What kind of graphics card do you have?

Try making a little c app that does the same type of lighting and see if you get the same results.  If it is the same you might have found a driver bug.