God knows what's modified

luprex/syscpp/cellgrid.hpp

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+//
+// Cellgrid: stores sprites in a grid.
+//
+// To create a grid, just create an empty table.
+// In actual usage, the cellgrid will be stored in the registry
+// in the field "cellgrid_cells".  If you pass grid=nil to
+// any of these routines, the system will automatically use
+// the table in the registry.
+//
+// For purposes of this module, a "sprite" is any table
+// having a metatable.  The (X,Y,Z,Plane) of the sprite are
+// stored as hidden fields inside the metatable.
+//
+// We preserve the invariant that sprites whose plane is nil
+// are not stored in the grid.  All sprites whose plane
+// is a string are stored in the grid.
+//
+// When creating a new sprite, initialize plane to nil.  That
+// fits the invariant that sprites whose plane is nil are
+// not stored in the grid.  If you ever want to change the
+// sprite's position, use cellgrid_setpos: that will
+// preserve the invariant.
+//
+
+#ifndef CELLGRID_HPP
+#define CELLGRID_HPP
+
+#include "luastack.hpp"
+
+int cellgrid_initgrid(lua_State *L);
+int cellgrid_addplane(lua_State *L);
+int cellgrid_setpos(lua_State *L);
+int cellgrid_scanradius(lua_State *L);
+int cellgrid_scanregion(lua_State *L);
+
+#endif // CELLGRID_HPP
+
+