diff --git a/luprex/syscpp/animqueue.cpp b/luprex/syscpp/animqueue.cpp
index d588711b..149cc5f0 100644
--- a/luprex/syscpp/animqueue.cpp
+++ b/luprex/syscpp/animqueue.cpp
@@ -1,5 +1,6 @@
 
 #include "animqueue.hpp"
+#include "luastack.hpp"
 #include <limits>
 
 
@@ -16,7 +17,7 @@ AnimQueue::AnimQueue(int size_limit) {
     init.xyz_ = util::XYZ(0,0,0);
     init.graphic_ = "nothing";
     init.plane_ = "nowhere";
-    init.bits_ = 0;
+    init.bits_ = AnimStep::HAS_EVERYTHING;
 }
 
 void AnimQueue::add(int64_t id, const std::string &action) {
@@ -33,7 +34,7 @@ void AnimQueue::add(int64_t id, const std::string &action) {
     AnimStep &init = steps_.front();
     init.id_ = 0;
     init.action_ = "";
-    init.bits_ = 0;
+    init.bits_ = AnimStep::HAS_EVERYTHING;
 }
 
 void AnimQueue::set_facing(float f) {
@@ -59,3 +60,64 @@ void AnimQueue::set_plane(const std::string &p) {
     last.bits_ |= AnimStep::HAS_PLANE;
     last.plane_ = p;
 }
+
+const std::string &AnimQueue::get_plane() const {
+    const AnimStep &last = steps_.back();
+    return last.plane_;
+}
+
+const util::XYZ &AnimQueue::get_xyz() const {
+    const AnimStep &last = steps_.back();
+    return last.xyz_;
+}
+
+LuaDefine(unittests_animqueue, "c") {
+    // Check initial state.
+    AnimQueue aq(3);
+    LuaAssert(L, aq.size() == 1);
+    const AnimStep *st = &aq.nth(0);
+    LuaAssert(L, st->id() == 0);
+    LuaAssert(L, st->action() == "");
+    LuaAssert(L, st->bits() == AnimStep::HAS_EVERYTHING);
+    LuaAssert(L, st->facing() == 0.0);
+    LuaAssert(L, st->xyz() == util::XYZ(0,0,0));
+    LuaAssert(L, st->graphic() == "nothing");
+    LuaAssert(L, st->plane() == "nowhere");
+
+    // Add a step.
+    aq.add(12345, "walk");
+    LuaAssert(L, aq.size() == 2);
+    st = &aq.nth(1);
+    LuaAssert(L, st->id() == 12345);
+    LuaAssert(L, st->action() == "walk");
+    LuaAssert(L, st->bits() == 0);
+    LuaAssert(L, st->facing() == 0.0);
+    LuaAssert(L, st->xyz() == util::XYZ(0,0,0));
+    LuaAssert(L, st->graphic() == "nothing");
+    LuaAssert(L, st->plane() == "nowhere");
+
+    // Test the setters.
+    aq.set_facing(180);
+    LuaAssert(L, st->facing() == 180);
+    LuaAssert(L, st->bits() == AnimStep::HAS_FACING);
+    aq.set_xyz(util::XYZ(3,4,5));
+    LuaAssert(L, st->xyz() == util::XYZ(3, 4, 5));
+    LuaAssert(L, st->bits() == (AnimStep::HAS_FACING | AnimStep::HAS_XYZ));
+    aq.set_plane("somewhere");
+    LuaAssert(L, st->plane() == "somewhere");
+    LuaAssert(L, st->bits() == (AnimStep::HAS_FACING | AnimStep::HAS_XYZ | AnimStep::HAS_PLANE));
+    aq.set_graphic("something");
+    LuaAssert(L, st->graphic() == "something");
+    LuaAssert(L, st->bits() == (AnimStep::HAS_FACING | AnimStep::HAS_XYZ | AnimStep::HAS_PLANE | AnimStep::HAS_GRAPHIC));
+    
+    // Exceed the length limit, dropping first element.
+    aq.add(12346, "walk");
+    aq.add(12347, "walk");
+    LuaAssert(L, aq.size() == 3);
+    LuaAssert(L, aq.nth(0).id() == 0);
+    LuaAssert(L, aq.nth(0).action() == "");
+    LuaAssert(L, aq.nth(0).bits() == AnimStep::HAS_EVERYTHING);
+    LuaAssert(L, aq.nth(1).id() == 12346);
+    LuaAssert(L, aq.nth(2).id() == 12347);
+    return 0;
+}
diff --git a/luprex/syscpp/animqueue.hpp b/luprex/syscpp/animqueue.hpp
index 002b0c9d..c3164bd6 100644
--- a/luprex/syscpp/animqueue.hpp
+++ b/luprex/syscpp/animqueue.hpp
@@ -39,6 +39,7 @@ public:
         HAS_XYZ = 2,
         HAS_GRAPHIC = 4,
         HAS_PLANE = 8,
+        HAS_EVERYTHING = 15,
     };     
 
 private:
@@ -85,6 +86,10 @@ public:
     void set_xyz(util::XYZ xyz);
     void set_graphic(const std::string &g);
     void set_plane(const std::string &p);
+
+    // Get the final resting place.
+    const std::string &get_plane() const;
+    const util::XYZ &get_xyz() const;
 };
 
 #endif // ANIMQUEUE_HPP
diff --git a/luprex/syscpp/idalloc.hpp b/luprex/syscpp/idalloc.hpp
index c50a5ecc..17213519 100644
--- a/luprex/syscpp/idalloc.hpp
+++ b/luprex/syscpp/idalloc.hpp
@@ -129,7 +129,7 @@ private:
 public:
     // Construct a player pool.
     // The Player pool stores a pointer to the global pool.
-    IdPlayerPool(IdGlobalPool *gp);
+    IdPlayerPool(IdGlobalPool *igp);
     ~IdPlayerPool();
 
     // Refill the fifo queue of batches from the global pool.
diff --git a/luprex/syscpp/main.cpp b/luprex/syscpp/main.cpp
index 1ff058d0..93bd89a2 100644
--- a/luprex/syscpp/main.cpp
+++ b/luprex/syscpp/main.cpp
@@ -14,7 +14,7 @@
 #include <string>
 #include "luastack.hpp"
 #include "util.hpp"
-#include "source.hpp"
+#include "world.hpp"
 #include "traceback.hpp"
 
 
@@ -174,43 +174,10 @@ static void dotty(lua_State *L)
     fflush(stdout);
 }
 
-static int pmain(lua_State *L)
-{
-    globalL = L;
-
-    LUAJIT_VERSION_SYM(); /* Linker-enforced version check. */
-
-    LuaStack::register_all_userdata(L);
-    
-    // Initialize the builtins, then copy a snapshot of the
-    // builtins to the registry.  The snapshot will allow us to restore
-    // the builtins during source_rebuild operations.
-    source_install_and_snapshot_builtins(L);
-
-    // Load the lua source.
-    source_update(L);
-
-    // Rebuild the global environment.
-    source_rebuild(L);
-
-    // Run unit tests.
-    source_run_unittests(L);
-    
-    dotty(L);
-    return 0;
-}
-
 int main(int argc, char **argv)
 {
-    int status;
-    lua_State *L = lua_open();
-    if (L == NULL)
-    {
-        l_message("cannot create state: not enough memory");
-        return -1;
-    }
-    status = lua_cpcall(L, pmain, NULL);
-    report(L, status);
-    lua_close(L);
-    return status ? -1 : 0;
+    LUAJIT_VERSION_SYM(); // Linker-enforced version check.
+    World w;
+    dotty(w.get_lua_state());
+    return 0;
 }
diff --git a/luprex/syscpp/planemap.cpp b/luprex/syscpp/planemap.cpp
index 54259b46..bb6a917a 100644
--- a/luprex/syscpp/planemap.cpp
+++ b/luprex/syscpp/planemap.cpp
@@ -13,7 +13,7 @@
 #define CELL_INVALID 0
 
 // Round a float and return as integer.  Clamp result to the specified range.
-static int round_and_clamp(double x, int lo, int hi) {
+static int round_and_clamp(float x, int lo, int hi) {
     x = round(x);
     if (x < lo) return lo;
     if (x > hi) return hi;
@@ -38,7 +38,7 @@ struct CellRange {
 // the map: in that case, returns exactly the valid cells and not the
 // invalid ones.
 //
-static CellRange rect_cell_range(double x1, double y1, double x2, double y2) {
+static CellRange rect_cell_range(float x1, float y1, float x2, float y2) {
     CellRange result;
     result.xlo = round_and_clamp(x1 / CELL_SCALE, -CELL_LIMIT, CELL_LIMIT + 1);
     result.ylo = round_and_clamp(y1 / CELL_SCALE, -CELL_LIMIT, CELL_LIMIT + 1);
@@ -54,9 +54,9 @@ static int64_t cell_id(int64_t cellx, int64_t celly) {
 }
 
 // Get the cell ID of the specified point, or CELL_INVALID if the point is off the map.
-static int64_t point_cell_id(double x, double y) {
-    double cellx = round(x / CELL_SCALE);
-    double celly = round(y / CELL_SCALE);
+static int64_t point_cell_id(float x, float y) {
+    float cellx = round(x / CELL_SCALE);
+    float celly = round(y / CELL_SCALE);
     if ((cellx < -CELL_LIMIT) || (celly < -CELL_LIMIT) || (cellx > CELL_LIMIT) || (celly > CELL_LIMIT)) {
         return CELL_INVALID;
     }
@@ -101,10 +101,10 @@ void PlaneMap::insert(const std::string &plane, int64_t cellid, PlaneItem *clien
     l.push_back(client);
 }
 
-void PlaneItem::set_pos(const std::string &plane, double x, double y, double z) {
-    int64_t old_cell = point_cell_id(x_, y_);
-    int64_t new_cell = point_cell_id(x, y);
-
+void PlaneItem::set_pos(const std::string &plane, const util::XYZ &xyz) {
+    int64_t old_cell = point_cell_id(xyz_.x, xyz_.y);
+    int64_t new_cell = point_cell_id(xyz.x, xyz.y);
+    
     // Update the grid.
     if (pmap_ != 0) {
         if ((plane_ != plane) || (old_cell != new_cell)) {
@@ -115,14 +115,12 @@ void PlaneItem::set_pos(const std::string &plane, double x, double y, double z)
 
     // Update the client position.
     plane_ = plane;
-    x_ = x;
-    y_ = y;
-    z_ = z;    
+    xyz_ = xyz;
 }
 
 void PlaneItem::untrack() {
     if (pmap_ != 0) {
-        pmap_->remove(plane_, point_cell_id(x_, y_), this);
+        pmap_->remove(plane_, point_cell_id(xyz_.x, xyz_.y), this);
         pmap_ = 0;
     }
 }
@@ -135,7 +133,7 @@ void PlaneMap::track(PlaneItem *item) {
     }
 }
 
-PlaneItem::PlaneItem() : pmap_(NULL), x_(0.0), y_(0.0), z_(0.0) {
+PlaneItem::PlaneItem() : pmap_(NULL), xyz_(0,0,0) {
 }
 
 PlaneMap::PlaneMap() {
@@ -176,13 +174,13 @@ int PlaneMap::total_cells() const {
     return total;
 }
 
-PlaneMap::EltVec PlaneMap::scan_radius(const std::string &plane, double x, double y, double radius) const {
+PlaneMap::EltVec PlaneMap::scan_radius(const std::string &plane, float x, float y, float radius) const {
     PlaneMap::EltVec result;
     auto piter = planes_.find(plane);
     if (piter != planes_.end()) {
         const Plane &p = piter->second;
         CellRange range = rect_cell_range(x - radius, y - radius, x + radius, y + radius);
-        double radsq = radius*radius;
+        float radsq = radius*radius;
         for (int cy = range.ylo; cy <= range.yhi; cy++) {
             for (int cx = range.xlo; cx <= range.xhi; cx++) {
                 auto liter = p.find(cell_id(cx, cy));
@@ -200,8 +198,8 @@ PlaneMap::EltVec PlaneMap::scan_radius(const std::string &plane, double x, doubl
 }
 
 LuaDefine(unittests_planemap, "c") {
-    double SC = CELL_SCALE;
-    double E = CELL_SCALE * 0.4;
+    float SC = CELL_SCALE;
+    float E = CELL_SCALE * 0.4;
     int LO = -CELL_LIMIT;
     int HI = CELL_LIMIT;
     PlaneMap pm;
@@ -314,5 +312,15 @@ LuaDefine(unittests_planemap, "c") {
     elts = pm.scan_radius("bar", 1000.0, 1000.0, 100.0);
     LuaAssert(L, elts.size() == 2);
     
+    // Test static_field_cast.
+    struct MyTangible {
+        int x, y, z;
+        PlaneItem plane_item_;
+    };
+    MyTangible tan;
+    PlaneItem *pip = &tan.plane_item_;
+    MyTangible *tanp = pip->static_field_cast<MyTangible>();
+    LuaAssert(L, tanp == &tan);
+    
     return 0;
 }
diff --git a/luprex/syscpp/planemap.hpp b/luprex/syscpp/planemap.hpp
index 9970e70b..b089c655 100644
--- a/luprex/syscpp/planemap.hpp
+++ b/luprex/syscpp/planemap.hpp
@@ -74,8 +74,10 @@
 #define PLANEMAP_HPP
 
 #include <cstdint>
+#include <cstddef>
 #include <vector>
 #include <map>
+#include "util.hpp"
 
 class PlaneMap;
 
@@ -85,20 +87,38 @@ class PlaneItem {
 private:
     PlaneMap *pmap_;
     std::string plane_;
-    double x_, y_, z_;
+    util::XYZ xyz_;
 
 public:
     PlaneItem();
     ~PlaneItem();
 
     const std::string &plane() const { return plane_; }
-    const double x() const { return x_; }
-    const double y() const { return y_; }
-    const double z() const { return z_; }
+    const util::XYZ &xyz() const { return xyz_; }
+    const float x() const { return xyz_.x; }
+    const float y() const { return xyz_.y; }
+    const float z() const { return xyz_.z; }
 
     void untrack();
-    void set_pos(const std::string &plane, double x, double y, double z);
-    void set_xyz(double x, double y, double z) { set_pos(plane_, x, y, z); }
+    void set_pos(const std::string &plane, const util::XYZ &xyz);
+    void set_pos(const std::string &plane, float x, float y, float z) { set_pos(plane, util::XYZ(x,y,z)); }
+    void set_xyz(const util::XYZ &xyz) { set_pos(plane_, xyz); }
+    void set_xyz(float x, float y, float z) { set_pos(plane_, util::XYZ(x, y, z)); }
+    
+    // Assume that some other object has methods 'get_plane' and 'get_xyz'.
+    // Get the plane and XYZ from that object and store it in this PlaneItem.
+    template<class T>
+    void set_pos_from(const T &obj) {
+        set_pos(obj.get_plane(), obj.get_xyz());
+    }
+
+    // Assume that the PlaneItem is a field in an object of class T.
+    // Static cast the PlaneItem pointer to a type T pointer.
+    template<class T>
+    T *static_field_cast() {
+        const std::size_t offset = offsetof(T, plane_item_);
+        return reinterpret_cast<T*>(reinterpret_cast<char*>(this) - offset);
+    }
 };
 
 class PlaneMap {
@@ -114,7 +134,7 @@ public:
     PlaneMap();
     ~PlaneMap();
     void track(PlaneItem *item);
-    EltVec scan_radius(const std::string &plane, double x, double y, double radius) const;
+    EltVec scan_radius(const std::string &plane, float x, float y, float radius) const;
     
 private:
     // unit testing stuff.
diff --git a/luprex/syscpp/source.cpp b/luprex/syscpp/source.cpp
index 167cebc0..55beb5d1 100644
--- a/luprex/syscpp/source.cpp
+++ b/luprex/syscpp/source.cpp
@@ -64,7 +64,7 @@ static void load_builtin(lua_State *L, const char *name, lua_CFunction func) {
     lua_call(L, 1, 0);
 }
 
-LuaDefine(source_install_builtins, "") {
+static void source_install_builtins(lua_State *L) {
     LuaStack LS(L);
     load_builtin(L, "base", luaopen_base);
     load_builtin(L, "table", luaopen_table);
@@ -72,11 +72,10 @@ LuaDefine(source_install_builtins, "") {
     load_builtin(L, "math", luaopen_math);
     load_builtin(L, "bit", luaopen_math);
     load_builtin(L, "debug", luaopen_debug);
-    // Do not load: package, io, os, debug, jit
-    return 0;
 }
 
-LuaDefine(source_install_and_snapshot_builtins, "") {
+void SourceDB::initialize(lua_State *L) {
+    lua_state_ = L;
     LuaVar key, value, skey, svalue, snapshot, ssnapshot;
     LuaStack LS(L, snapshot, key, value, skey, svalue, ssnapshot);
 
@@ -99,10 +98,10 @@ LuaDefine(source_install_and_snapshot_builtins, "") {
         }
     }
     LS.setfield(LuaRegistry, "source_snapshot_builtins", snapshot);
-    return LS.result();
+    LS.result();
 }
 
-LuaDefine(source_updatefile, "") {
+static int source_updatefile(lua_State *L) {
     LuaArg source, fn;
     LuaRet info;
     LuaVar fingerprint, null;
@@ -127,7 +126,7 @@ LuaDefine(source_updatefile, "") {
     if (LS.isstring(fingerprint)) {
         old_fingerprint = LS.ckstring(fingerprint);
     }
-    std::cerr << "Probing " << cfn << std::endl;
+    // std::cerr << "Probing " << cfn << std::endl;
     std::string new_fingerprint = util::get_file_fingerprint("syslua/" + cfn);
     LS.set(null, LuaNil);
     if ((old_fingerprint == "") || (old_fingerprint != new_fingerprint)) {
@@ -147,7 +146,8 @@ LuaDefine(source_updatefile, "") {
     return LS.result();
 }
 
-LuaDefine(source_update, "c") {
+void SourceDB::update() {
+    lua_State *L = lua_state_;
     LuaVar sourcedb, newdb, info, fn, seq;
     LuaStack LS(L, newdb, sourcedb, info, fn, seq);
 
@@ -180,13 +180,13 @@ LuaDefine(source_update, "c") {
 
     // Store the new source db.
     LS.setfield(LuaRegistry, "sourcedb", newdb);
-    return LS.result();
+    LS.result();
 }
 
 // Delete everything from the global environment except
 // the class tables and the class action tables.
 //
-LuaDefine(source_clear_globals, "") {
+static void source_clear_globals(lua_State *L) {
     LuaVar classname, classtab, action, key;
     LuaStack LS(L, classname, classtab, action, key);
 
@@ -209,12 +209,12 @@ LuaDefine(source_clear_globals, "") {
         }
     }
     LS.setfield(LuaGlobals, "_G", LuaGlobals);
-    return LS.result();
+    LS.result();
 }
 
 // Restore the lua builtins from the backup snapshot.
 //
-LuaDefine(source_restore_builtins, "") {
+static void source_restore_builtins(lua_State *L) {
     LuaVar snapshot, key, value, skey, svalue, subglobal;
     LuaStack LS(L, snapshot, key, value, skey, svalue, subglobal);
 
@@ -229,12 +229,12 @@ LuaDefine(source_restore_builtins, "") {
             LS.rawset(subglobal, skey, svalue);
         }
     }
-    return LS.result();
+    LS.result();
 }
 
 // Load all the 'LuaDefine' C functions into the lua state.
 //
-LuaDefine(source_load_cfunctions, "") {
+static void source_load_cfunctions(lua_State *L) {
     auto regs = LuaFunctionReg::all();
     for (const LuaFunctionReg *r : regs) {
         const std::string &name = r->get_name();
@@ -260,12 +260,11 @@ LuaDefine(source_load_cfunctions, "") {
             lua_setglobal(L, funcname.c_str());
         }
     }
-    return 0;
 }
 
 // Run all the closures from the source database.
 //
-LuaDefine(source_load_lfunctions, "") {
+static void source_load_lfunctions(lua_State *L) {
     LuaRet errors;
     LuaVar sourcedb, key, info, seq, closure, err;
     LuaStack LS(L, sourcedb, errors, key, info, seq, closure, err);
@@ -305,10 +304,11 @@ LuaDefine(source_load_lfunctions, "") {
         }
     }
     LS.set(errors, errss.str());
-    return LS.result();
+    LS.result();
 }
 
-LuaDefine(source_rebuild, "c") {
+void SourceDB::rebuild() {
+    lua_State *L = lua_state_;
     LuaVar errs;
     LuaStack LS(L, errs);
     source_clear_globals(L);
@@ -318,13 +318,13 @@ LuaDefine(source_rebuild, "c") {
     lua_replace(L, errs.index());
     std::string errstr = LS.ckstring(errs);
     std::cerr << errstr;
-    return LS.result();
+    LS.result();
 }
 
-LuaDefine(source_run_unittests, "c") {
+void SourceDB::run_unittests() {
+    lua_State *L = lua_state_;
     LuaVar unittests, name, func, err;
-    LuaRet rescode;
-    LuaStack LS(L, unittests, name, func, err, rescode);
+    LuaStack LS(L, unittests, name, func, err);
 
     LS.getfield(unittests, LuaGlobals, "unittests");
 
@@ -351,8 +351,9 @@ LuaDefine(source_run_unittests, "c") {
         }
     }
 
-    // Return 1 if any errors.
-    LS.set(rescode, any ? 1 : 0);
-    return LS.result();
+    if (any) {
+        exit(1);
+    }
+    LS.result();
 }
 
diff --git a/luprex/syscpp/source.hpp b/luprex/syscpp/source.hpp
index 44ef7025..614477ac 100644
--- a/luprex/syscpp/source.hpp
+++ b/luprex/syscpp/source.hpp
@@ -1,6 +1,6 @@
 ////////////////////////////////////////////////////////////
 //
-// SOURCE
+// SOURCEDB
 //
 // This module manages the loading of lua source files into the Lua environment.
 // Since the source files can be reloaded over and over, this module doesn't
@@ -9,7 +9,6 @@
 // that should be there.  That way, if you delete something from a lua source
 // file, it gets removed from the lua global environment.
 //
-//
 // THE MAKECLASS OPERATOR
 //
 // This module provides a new lua 'builtin' operator: "makeclass". This creates
@@ -31,12 +30,15 @@
 //
 // THE LUA SOURCE DATABASE
 //
-// The function 'source_update' loads the lua source code from disk, and stores
-// it in the "source database."  The source database is a table inside the lua
-// registry.
+// Class SourceDB only contains a single pointer to the lua environment. That's
+// because all the data for SourceDB is stored in the lua registry.
+// Specifically, the registry contains these keys:
 //
-// The source database is a lua table where the keys are filenames, and the
-// values are information about that file:
+//     1. The source database proper (registry key "sourcedb")
+//     2. The snapshot of builtins (registry key "source_snapshot_builtins")
+//
+// The source database proper is a table where the keys are filenames, and the
+// values are records containing information about that file:
 //
 //     "foo.lua" : {
 //         "name":        "foo.lua",
@@ -55,23 +57,24 @@
 // error message. Finally, "sequence" indicates the order in which the source
 // files are meant to be loaded.
 //
-// The operation "source_update" refreshes the source database from disk.  It
+// The operation SourceDB::update refreshes the source database from disk.  It
 // doesn't reread files whose fingerprints have not changed. In a synchronous
-// model, we don't call source_update - instead, we update the source database
-// by difference transmission.
+// model, we don't call SourceDB::update - instead, we update the source
+// database by difference transmission.
 //
 // Note that updating the source database has *no effect* on the lua global
-// variables (or lua function definitions).  The source_update operation calls
-// lua's "load" on the code, but all that does is return a loaded closure.
+// variables (or lua function definitions).  The SourceDB::update operation
+// calls lua's "load" on the code, but all that does is return a loaded closure.
 // Nothing happens to the lua invironment until you *invoke* the loaded closure.
-// That doesn't happen until you do a source_rebuild operation, described below.
+// That doesn't happen until you do a SourceDB::rebuild operation, described
+// below.
 //
 //
 // SOURCE REBUILDS, IN DEPTH
 //
-// The function source_rebuild clears and then rebuilds the entire contents of
-// the global environment.  The reason to clear the environment is that if we
-// didn't clear it, then removing a function from the lua source would not
+// The function SourceDB::rebuild clears and then rebuilds the entire contents
+// of the lua global environment.  The reason to clear the environment is that
+// if we didn't clear it, then removing a function from the lua source would not
 // remove it from the lua environment.  Rebuilding the lua environment is a
 // multi-step process:
 //
@@ -83,7 +86,7 @@
 //
 // * Lua Builtin functions are reinstalled in the global environment.
 //
-//     - To make this possible, a snapshot of these builtins is kept.
+//     - To make this possible, the snapshot of builtins is used.
 //
 // * C++ functions registered with "LuaDefine" are reinstalled.
 //
@@ -102,15 +105,15 @@
 // UNITTESTS
 //
 // We reserve the lua class name 'unittests' for storing unit tests.  Any
-// function placed into this class is considered a unit test.  We don't
-// separate unit tests from the rest of the code - they're compiled right
-// into the main binary.
+// function placed into this class is considered a unit test.  We don't separate
+// unit tests from the rest of the code - they're compiled right into the main
+// binary.
 //
-// Unit tests can be either lua functions, or Lua-registered C functions.
-// Unit tests are executed by calling 'source_run_unittests'.
+// Unit tests can be either lua functions, or Lua-registered C functions. Unit
+// tests are executed by calling 'source_run_unittests'.
 //
-// Each unit test is run in a protected 'pcall' environment.  Any errors
-// are printed out to console. (At least for now).
+// Each unit test is run in a protected 'pcall' environment.  Any errors are
+// printed out to console. (At least for now).
 //
 ////////////////////////////////////////////////////////////
 
@@ -119,6 +122,46 @@
 
 #include "luastack.hpp"
 
+class SourceDB {
+private:
+    lua_State *lua_state_;
+
+public:
+    // Initialize
+    //
+    // This must be called while the lua state is still pristine.
+    // This will install the builtin operators into the lua state
+    // and will snapshot those builtins to the registry.
+    //
+    void initialize(lua_State *L);
+
+    // Update
+    //
+    // Read all the lua source files from disk and store them in the
+    // source database.  Also compiles these files using lua's "load"
+    // function.  Efficient: if a source file is already in the database
+    // and hasn't been modified, it is not reloaded.
+    //
+    void update();
+
+    // Rebuild
+    //
+    // Rebuild the lua environment: clear it out, then reinstall all the
+    // functions that should be there.  See above for more information.
+    // If an error exists in any of the source files, or when loading any
+    // of the closures, the error is (currently) printed.  We'll come up
+    // with better error handling later.
+    //
+    void rebuild();
+
+    // run_unittests
+    //
+    // Run all the unit tests.  Print any errors to console.  If there
+    // are any errors, exits the program.
+    //
+    void run_unittests();
+};
+
 // The Lua 'makeclass' operator.
 //
 // Creates a table in the global environment with the specified name.
@@ -128,41 +171,6 @@
 //
 int source_makeclass(lua_State *L);
 
-// source_install_and_snapshot_builtins.
-//
-// Install the lua builtins into a brand new lua state, and then create the
-// snapshot of the builtins (in the registry). This uses lua_openlibs, which
-// only works if the lua environment is brand new. Do not try to use
-// source_snapshot_builtins unless the lua environment has just been created
-// using lua_newstate!
-//
-int source_install_and_snapshot_builtins(lua_State *L);
-
-// source_update
-//
-// Read all the lua source files from disk and store them in the
-// source database.  Also compiles these files using lua's "load"
-// function.  Efficient: if a source file is already in the database
-// and hasn't been modified, it is not reloaded.
-//
-int source_update(lua_State *L);
-
-// source_rebuild
-//
-// Rebuild the lua environment: clear it out, then reinstall all the
-// functions that should be there.  See above for more information.
-// If an error exists in any of the source files, or when loading any
-// of the closures, the error is (currently) printed.  We'll come up
-// with better error handling later.
-//
-int source_rebuild(lua_State *L);
-
-// source_run_unittests
-//
-// Run all the unit tests.  Print any errors to console.  Pushes zero
-// onto the lua stack if there are no errors, or one if there are.
-//
-int source_run_unittests(lua_State *L);
 
 #endif // SOURCE_HPP
 
diff --git a/luprex/syscpp/util.hpp b/luprex/syscpp/util.hpp
index 03fad372..3218c544 100644
--- a/luprex/syscpp/util.hpp
+++ b/luprex/syscpp/util.hpp
@@ -6,6 +6,7 @@
 #include <algorithm>
 #include <sstream>
 #include <tuple>
+#include <utility>
 
 namespace util {
 
@@ -48,6 +49,7 @@ struct XYZ {
     float x, y, z;
     XYZ() { x=0; y=0; z=0; }
     XYZ(float ix, float iy, float iz) { x=ix; y=iy; z=iz; }
+    bool operator ==(const XYZ &o) { return x==o.x && y == o.y && z==o.z; }
 };
 
 } // namespace util
diff --git a/luprex/syscpp/world.cpp b/luprex/syscpp/world.cpp
index 62d4f4b7..3e801f27 100644
--- a/luprex/syscpp/world.cpp
+++ b/luprex/syscpp/world.cpp
@@ -1,17 +1,41 @@
 
 #include "world.hpp"
 #include "idalloc.hpp"
+#include <iostream>
 
 LuaDefineType(World);
 
 World::~World() {
 }
 
-void World::init(lua_State *L) {
+World::World() {
+    // Create the lua state.
+    lua_state_ = lua_open();
+    if (lua_state_ == nullptr) {
+        std::cerr << "Cannot create lua state." << std::endl;
+        exit(1);
+    }
+
+    // Initialize the userdata metatables.
+    LuaStack::register_all_userdata(lua_state_);
+    
+    // Prepare to manipulate the lua state.
     LuaVar world;
-    LuaStack LS(L, world);
-    LS.newpointer(world, new World, false);
+    LuaStack LS(lua_state_, world);
+
+    // Put the world pointer into the lua registry.
+    LS.newpointer(world, this, false);
     LS.setfield(LuaRegistry, "world", world);
+
+    // Initialize the SourceDB
+    source_db_.initialize(lua_state_);
+
+    // Do an initial lua source update and then environment rebuild.
+    source_db_.update();
+    source_db_.rebuild();
+
+    // Run unit tests.
+    source_db_.run_unittests();
 }
 
 World *World::fetch(lua_State *L) {
@@ -23,23 +47,3 @@ World *World::fetch(lua_State *L) {
     return w;
 }
 
-LuaDefine(world_init, "c") {
-    World::init(L);
-    return 0;
-}
-
-LuaDefine(world_setid, "c") {
-    LuaArg id;
-    LuaStack LS(L, id);
-    World *w = World::fetch(L);
-    w->id_ = LS.ckinteger(id);
-    return LS.result();
-}
-
-LuaDefine(world_getid, "c") {
-    LuaRet id;
-    LuaStack LS(L, id);
-    World *w = World::fetch(L);
-    LS.set(id, w->id_);
-    return LS.result();
-};
\ No newline at end of file
diff --git a/luprex/syscpp/world.hpp b/luprex/syscpp/world.hpp
index b37f44d1..c1ee3a87 100644
--- a/luprex/syscpp/world.hpp
+++ b/luprex/syscpp/world.hpp
@@ -1,30 +1,78 @@
-// Note about header file dependencies:
-//
-//    world.hpp contains a lot of forward declarations.
-//    That's because it is at the bottom of the dependency stack:
-//    everyone includes world.hpp.
-//
-//    However, world.cpp is at the top of the dependency stack,
-//    it includes everyone else.
-//
 
 #ifndef WORLD_HPP
 #define WORLD_HPP
 
 #include "luastack.hpp"
+#include "planemap.hpp"
+#include "idalloc.hpp"
+#include "animqueue.hpp"
+#include "source.hpp"
 #include <memory>
+#include <unordered_map>
 
-class IdGlobalPool;
+class World;
+
+class Tangible {
+public:
+    // Always points back to the world model.
+    World *world_;
+
+    // Animation queue and plane item.
+    //
+    // To update the position of this tangible, first add an animation in which
+    // the tangible moves, then call plane_item.set_pos_from(anim_queue_).
+    PlaneItem plane_item_;
+    AnimQueue anim_queue_;
+
+    // Player ID pool
+    //
+    // Note: this is only allocated if this Tangible is a player.
+    std::unique_ptr<IdPlayerPool> id_player_pool_;
+};
 
 class World {
 public:
-    int id_;
-    std::unique_ptr<IdGlobalPool> id_pool_;
-    
-    World() : id_(0) {};
+    // A pointer to the lua State.
+    //
+    lua_State *lua_state_;
+
+    // The Global ID Pool.
+    //
+    IdGlobalPool id_global_pool_;
+
+    // Source Database.
+    //
+    SourceDB source_db_;
+    PlaneMap plane_map_;
+    std::unordered_map<int64_t, Tangible> tangibles_;
+
+public:
+    // Constructor.
+    //
+    // The constructor also calls 'lua_open' to create a new
+    // lua interpreter for this world model.  The lua interpreter
+    // is stored in world::lua_state_.  A significant amount of
+    // initial setup is done by this constructor.
+    //
+    World();
+
+    // Destructor.
+    //
+    // Not currently functional.
+    //
     ~World();
 
-    static void init(lua_State *L);
+    // get_lua_state
+    //
+    // Get the lua interpreter associated with this world model.
+    //
+    lua_State *get_lua_state() { return lua_state_; }
+
+    // fetch
+    //
+    // Given a lua state, fetch the world model associated with
+    // that lua state.
+    //
     static World *fetch(lua_State *L);
 };