[Gzz] PEG vobcoorder_culling--humppake

[Asko Soukka]

================================================================================
PEG vobcoorder_culling--humppake: Interface for creating
``CullingCoordSys``
================================================================================
:Authors:  Asko Soukka
:Stakeholders: Tuomas Lukka
:Status: Current
:Scope:  Minor
:Type:  Feature

``CullingCoordSys`` can be currently created through its interface in
``GLVobCoorder``. This peg is about making culling also as a part of
general ``VobCoorder`` interface.

Changes
-------

Into ``gzz.vob.VobCoorder`` add::
        /** Creates a CullingCoordSys with distinct parent and test
         * coordinate systems. The CullingCoordSys works mainly as its
         * parent CoordSys. Although, it will be drawn always when boxes
         * of its test and clip coordinate systems do intersect. When
         * the boxes don't intersect, the CullingCoordSys should not be
         * drawn.
         * @param parent ID of the coordinate system which points which
         *               points will be transformed, if CullingCoordSys is
         *               shown
         * @param test ID of the coordinate system which box is tested
         *        against the clip coordinate system.
         * @param clip ID of the coordinate system which box is tested
         *             against the test coordinate system.
         */
        public int cull(int parent, int test, int clip) {
        }
        /** Creates a CullingCoordSys using the parent also as the test
         * coordinate system. In practise, this could be only a shorthand,
         * which returns a call cull(parent, parent, clip).
         */
        public int cull(int parent, int clip) {
        }

After changing ``gzz.vob.VobCoorder`` these methods should also
be implemented in all implementing classes, which inherit
``gzz.vob.VobCoorder``. Because culling is already implemented in
``gzz.gfx.gl.GLVobCoorder``, currently classes left seem to be:

 * ``gzz.vob.impl.OrthoCoorder``

  **NOTE:** ``CullingCoordsys`` is currently implemented only on the
  C++ side, but ``OrthoCoorder`` is not allowed to use JNI. *Dummy*
  ``CullingCoordSys`` can be implented on the Java side as
  ``translate(parent, 0, 0)``.~

-- 
Asko Soukka     | Taitoniekantie 9 A 603 | address@hidden
+358-40-8235947 | FIN-40740 JYVÄSKYLÄ    | http://www.iki.fi/asko.soukka/