Restart-without-quit support: lovr.event.quit("restart") and return-from-run() both support the string "restart" in place of an exit code. When this happens, the program reruns itself in a new, isolated environment. In Emscripten, no reboot occurs and the program only quits.

src/api/event.c

@@ -15,7 +15,10 @@ static int nextEvent(lua_State* L) {
   switch (event.type) {
     case EVENT_QUIT: {
       lua_pushstring(L, "quit");
-      lua_pushnumber(L, event.data.quit.exitCode);
+      if (event.data.quit.restart)
+        lua_pushliteral(L, "restart");
+      else
+        lua_pushnumber(L, event.data.quit.exitCode);
       return 2;
     }
 
@@ -125,11 +128,22 @@ int l_lovrEventPush(lua_State* L) {
 }
 
 int l_lovrEventQuit(lua_State* L) {
-  int exitCode = luaL_optint(L, 1, 0);
-  lua_settop(L, 0);
-  lua_pushliteral(L, "quit");
-  lua_pushinteger(L, exitCode);
-  return l_lovrEventPush(L);
+  EventData data;
+
+  int argType = lua_type(L, 1);
+  if (argType == LUA_TSTRING && 0 == strcmp("restart", lua_tostring(L, 1))) {
+    data.quit.restart = true;
+    data.quit.exitCode = 0;
+  } else if (argType == LUA_TNUMBER || lua_isnoneornil(L, 1)) {
+    data.quit.restart = false;
+    data.quit.exitCode = luaL_optint(L, 1, 0);
+  } else {
+    return luaL_argerror (L, 1, "number, nil or the exact string 'restart' expected");
+  }
+
+  EventType type = EVENT_QUIT;
+  Event event = { .type = type, .data = data };
+  lovrEventPush(event);
 }
 
 const luaL_Reg lovrEvent[] = {

src/audio/audio.c

@@ -3,10 +3,16 @@
 #include "math/quat.h"
 #include "util.h"
 #include <stdlib.h>
+#include "lovr.h"
 
 static AudioState state;
+static bool audioAlreadyInit = false;
 
 void lovrAudioInit() {
+  if (audioAlreadyInit) { // During a reload, bring down the audio device then recreate it
+    lovrAudioDestroy();
+  }
+
   ALCdevice* device = alcOpenDevice(NULL);
   lovrAssert(device, "Unable to open default audio device");
 
@@ -31,7 +37,10 @@ void lovrAudioInit() {
   vec3_set(state.position, 0, 0, 0);
   vec3_set(state.velocity, 0, 0, 0);
 
-  atexit(lovrAudioDestroy);
+  if (!audioAlreadyInit) {
+    atexit(lovrAudioDestroy);
+    audioAlreadyInit = true;
+  }
 }
 
 void lovrAudioDestroy() {

src/event/event.c

@@ -3,12 +3,18 @@
 #include <stdlib.h>
 
 static EventState state;
+bool eventAlreadyInit = false;
 
 void lovrEventInit() {
+  if (eventAlreadyInit)
+    lovrEventDestroy();
   vec_init(&state.pumps);
   vec_init(&state.events);
   lovrEventAddPump(glfwPollEvents);
-  atexit(lovrEventDestroy);
+  if (!eventAlreadyInit) {
+    atexit(lovrEventDestroy);
+    eventAlreadyInit = true;
+  }
 }
 
 void lovrEventDestroy() {

src/event/event.h

@@ -14,6 +14,7 @@ typedef enum {
 } EventType;
 
 typedef struct {
+  bool restart;
   int exitCode;
 } QuitEvent;
 

src/filesystem/filesystem.c

@@ -4,6 +4,7 @@
 #include <physfs.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include "lovr.h"
 #ifdef __APPLE__
 #include <mach-o/dyld.h>
 #endif
@@ -20,7 +21,13 @@
 
 static FilesystemState state;
 
+bool filesystemAlreadyInit = false;
+
 void lovrFilesystemInit(const char* arg0, const char* arg1) {
+  if (filesystemAlreadyInit) // Do not change settings during a reload, and don't try to initialize PhysFS twice
+    return;
+  filesystemAlreadyInit = true;
+
   if (!PHYSFS_init(arg0)) {
     lovrThrow("Could not initialize filesystem: %s", PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode()));
   }

src/graphics/graphics.c

@@ -13,6 +13,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <math.h>
+#include "lovr.h"
 
 static GraphicsState state;
 
@@ -164,8 +165,16 @@ void lovrGraphicsPrepare(Material* material, float* pose) {
   lovrShaderBind(shader);
 }
 
+static bool graphicsAlreadyInit = false;
+
 void lovrGraphicsCreateWindow(int w, int h, bool fullscreen, int msaa, const char* title, const char* icon) {
-  lovrAssert(!state.window, "Window is already created");
+  if (graphicsAlreadyInit) {
+    lovrGraphicsReset();
+    return;
+  } else {
+    lovrAssert(!state.window, "Window is already created");
+    graphicsAlreadyInit = true;
+  }
 
 #ifdef EMSCRIPTEN
   glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_ES_API);

src/headset/headset.c

@@ -7,6 +7,7 @@ void lovrControllerDestroy(const Ref* ref) {
 }
 
 static HeadsetInterface* headset = NULL;
+static bool headsetAlreadyInit = false;
 
 void lovrHeadsetInit(HeadsetDriver* drivers, int count) {
   for (int i = 0; i < count; i++) {
@@ -28,9 +29,10 @@ void lovrHeadsetInit(HeadsetDriver* drivers, int count) {
     }
   }
 
-  if (headset) {
+  if (!headsetAlreadyInit && headset) {
     headset->init();
     atexit(lovrHeadsetDestroy);
+    headsetAlreadyInit = true;
   }
 }
 

src/lib/lua-enet/enet.c

@@ -31,6 +31,7 @@
 #include "lualib.h"
 #include "lauxlib.h"
 #include <enet/enet.h>
+#include <stdbool.h>
 
 #define check_host(l, idx)\
 	*(ENetHost**)luaL_checkudata(l, idx, "enet_host")
@@ -768,9 +769,14 @@ static const struct luaL_Reg enet_peer_funcs [] = {
 	{NULL, NULL}
 };
 
+static bool enitAlreadyInit = false;
+
 int luaopen_enet(lua_State *l) {
 	enet_initialize();
-	atexit(enet_deinitialize);
+	if (!enitAlreadyInit) {
+		atexit(enet_deinitialize);
+		enitAlreadyInit = true;
+	}
 
 	// create metatables
 	luaL_newmetatable(l, "enet_host");

src/lovr.c

@@ -63,6 +63,8 @@ static int lovrSetConf(lua_State* L) {
   return 0;
 }
 
+static bool glfwAlreadyInit = false;
+
 void lovrInit(lua_State* L, int argc, char** argv) {
   if (argc > 1 && strcmp(argv[1], "--version") == 0) {
     printf("LOVR %d.%d.%d (%s)\n", LOVR_VERSION_MAJOR, LOVR_VERSION_MINOR, LOVR_VERSION_PATCH, LOVR_VERSION_ALIAS);
@@ -72,9 +74,10 @@ void lovrInit(lua_State* L, int argc, char** argv) {
   glfwSetTime(0);
   glfwSetErrorCallback(onGlfwError);
 
-  if (!glfwInit()) {
+  if (!glfwAlreadyInit && !glfwInit()) {
     lovrThrow("Error initializing glfw");
   }
+  glfwAlreadyInit = true;
 
   // arg global
   lua_newtable(L);
@@ -141,7 +144,7 @@ static void emscriptenLoop(void* arg) {
   lua_call(L, 0, 0);
 }
 
-void lovrRun(lua_State* L) {
+bool lovrRun(lua_State* L) {
 
   // lovr.load
   lua_getglobal(L, "lovr");
@@ -158,9 +161,10 @@ void lovrRun(lua_State* L) {
   }
 
   emscripten_set_main_loop_arg(emscriptenLoop, (void*) L, 0, 1);
+  return false;
 }
 #else
-void lovrRun(lua_State* L) {
+bool lovrRun(lua_State* L) {
   lovrCatch = malloc(sizeof(jmp_buf));
 
   // Global error handler
@@ -175,7 +179,7 @@ void lovrRun(lua_State* L) {
     lua_pushstring(L, lovrErrorMessage);
     lua_pcall(L, 1, 1, 0);
     handleError(L, lua_tostring(L, -1));
-    return;
+    return false;
   }
 
   // lovr.run()
@@ -187,9 +191,21 @@ void lovrRun(lua_State* L) {
   }
 
   // Exit with return value from lovr.run
-  int exitCode = luaL_optint(L, -1, 0);
-  lua_pop(L, 2);
+  int exitCode = 0;
+  int returnType = lua_type(L, -1);
+  bool reloading = false;
+  if (returnType == LUA_TSTRING && 0 == strcmp("restart", lua_tostring(L, -1))) {
+    reloading = true; // Treat "restart" as special
+  } else if (returnType == LUA_TNUMBER || lua_isnoneornil(L, -1)) {
+    exitCode = luaL_optint(L, -1, 0);
+  } else {
+    luaL_argerror (L, -1, "number or the exact string 'restart' expected");
+  }
+
   free(lovrCatch);
-  lovrDestroy(exitCode);
+  lovrCatch = NULL;
+  if (!reloading)
+    lovrDestroy(exitCode);
+  return reloading;
 }
 #endif

src/lovr.h

@@ -1,4 +1,5 @@
 #include "luax.h"
+#include <stdbool.h>
 
 #define LOVR_VERSION_MAJOR 0
 #define LOVR_VERSION_MINOR 9
@@ -7,4 +8,4 @@
 
 void lovrInit(lua_State* L, int argc, char** argv);
 void lovrDestroy(int exitCode);
-void lovrRun(lua_State* L);
+bool lovrRun(lua_State* L); // Returns true to request continue

src/main.c

@@ -1,11 +1,14 @@
 #include "lovr.h"
 
 int main(int argc, char** argv) {
-  lua_State* L = luaL_newstate();
-  luaL_openlibs(L);
+  bool reloading;
+  do {
+	lua_State* L = luaL_newstate();
+	luaL_openlibs(L);
 
-  lovrInit(L, argc, argv);
-  lovrRun(L);
+    lovrInit(L, argc, argv);
+    reloading = lovrRun(L);
+  } while (reloading);
 
   return 0;
 }

src/math/math.c

@@ -3,14 +3,19 @@
 #include <math.h>
 #include <stdlib.h>
 #include <time.h>
+#include <stdbool.h>
 
 static RandomGenerator* generator;
+bool mathAlreadyInit = false;
 
 void lovrMathInit() {
   generator = lovrRandomGeneratorCreate();
   Seed seed = { .b64 = (uint64_t) time(0) };
 	lovrRandomGeneratorSetSeed(generator, seed);
-  atexit(lovrMathDestroy);
+  if (!mathAlreadyInit) {
+    atexit(lovrMathDestroy);
+    mathAlreadyInit = true;
+  }
 }
 
 void lovrMathDestroy() {

src/physics/physics.c

@@ -28,9 +28,15 @@ static void raycastCallback(void* data, dGeomID a, dGeomID b) {
   }
 }
 
+static bool odeAlreadyInit = false;
+
 void lovrPhysicsInit() {
+  if (odeAlreadyInit)
+    return;
+
   dInitODE();
   atexit(lovrPhysicsDestroy);
+  odeAlreadyInit = true;
 }
 
 void lovrPhysicsDestroy() {