add ComputeDispatch class

revoke glDispatch in PCProgram::useProgram
update example

include/osg/ComputeDispatch

@@ -0,0 +1,48 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2014 Robert Osfield
+ * Copyright (C) 2017 Julien Valentin
+ *
+ * This library is open source and may be redistributed and/or modified under
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * OpenSceneGraph Public License for more details.
+*/
+
+#ifndef OSG_COMPUTEDISPATCH
+#define OSG_COMPUTEDISPATCH 1
+
+#include <osg/Export>
+
+#include <osg/Geometry>
+
+namespace osg{
+    class OSG_EXPORT ComputeDispatch : public osg::Drawable
+    {
+        public:
+            ComputeDispatch(GLint numGroupsX=0, GLint numGroupsY=0, GLint numGroupsZ=0  ):
+                Drawable(),
+                _numGroupsX(numGroupsX),
+                _numGroupsY(numGroupsY),
+                _numGroupsZ(numGroupsZ)
+            {}
+
+            ComputeDispatch(const ComputeDispatch&,const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY);
+
+            META_Node(osg, ComputeDispatch);
+
+
+            virtual void drawImplementation(RenderInfo& renderInfo) const;
+             /** Set/get compute shader work groups */
+            void setComputeGroups( GLint numGroupsX, GLint numGroupsY, GLint numGroupsZ ) { _numGroupsX=numGroupsX,_numGroupsY=numGroupsY, _numGroupsZ=numGroupsZ; }
+            void getComputeGroups( GLint& numGroupsX, GLint& numGroupsY, GLint& numGroupsZ ) const{ numGroupsX=_numGroupsX; numGroupsY=_numGroupsY; numGroupsZ=_numGroupsZ; }
+        protected:
+            GLint _numGroupsX, _numGroupsY, _numGroupsZ;
+
+    };
+}
+#endif
+