feat(launcher): Set CVARs from the command line

cfg/launcher.cfg

@@ -0,0 +1,6 @@
+rt_Renderer = vk
+rt_WindowTitle = "rtengine"
+rt_WindowWidth = 1024
+rt_WindowHeight = 768
+rt_WindowMode = 0
+rt_GameLib = "(null)"

src/launcher/game_api.h

@@ -2,15 +2,20 @@
 #define RT_LAUNCHER_GAME_API_H
 
 #include <runtime/runtime.h>
+#include <runtime/timing.h>
 
 typedef void rt_game_register_cvars_fn(void);
 typedef rt_result rt_game_initialize_fn(void);
-typedef void rt_game_shutdown(void);
+typedef void rt_game_shutdown_fn(void);
+typedef void rt_game_update_fn(rt_time_delta delta);
+typedef void rt_game_render_fn(void);
 
 typedef struct {
     rt_game_register_cvars_fn *RegisterCVARs;
     rt_game_initialize_fn *Init;
-    rt_game_shutdown *Shutdown;
+    rt_game_shutdown_fn *Shutdown;
+    rt_game_update_fn *Update;
+    rt_game_render_fn *Render;
 } rt_game_api;
 
 

src/launcher/launcher.c

@@ -1,6 +1,6 @@
-#include "runtime/aio.h"
 #include "runtime/file_tab.h"
 #include "runtime/mem_arena.h"
+#include "runtime/timing.h"
 
 #ifdef __WIN32
 #define GLFW_EXPOSE_NATIVE_WIN32
@@ -29,6 +29,13 @@ RT_CVAR_I(rt_WindowMode, "The window mode. Available options: 0 (=Windowed), 1 (
 RT_CVAR_I(rt_FullscreenRefreshRate, "Requested refresh rate for exclusive fullscreen. Set to 0 to use the monitors current setting. (Default: 0)", 0);
 RT_CVAR_S(rt_Monitor, "Name of the monitor on which the window should be created. Leave empty to use the primary monitor. (Default: "")", "");
 
+RT_CVAR_F(rt_Framerate, "Target framerate in FPS. (Default: 60.0)", 60.0);
+
+/* These are for experiments and debugging */
+RT_CVAR_I(rt_LauncherCreateGLContext, "Create an OpenGL context in the launcher. 1: on, 0: off. (Default: 0)", 0);
+RT_CVAR_I(rt_LauncherGLContextMajor, "OpenGL Major version. (Default: 4)", 4);
+RT_CVAR_I(rt_LauncherGLContextMinor, "OpenGL minor version. (Default: 5)", 5);
+
 RT_CVAR_S(rt_GameLib, "Path to the game library. Only usable in internal builds. (Default: "")", "");
 
 enum {
@@ -57,6 +64,12 @@ static void SetupConfig(void) {
     rtRegisterCVAR(&rt_WindowMode);
     rtRegisterCVAR(&rt_Monitor);
 
+    rtRegisterCVAR(&rt_Framerate);
+
+    rtRegisterCVAR(&rt_LauncherCreateGLContext);
+    rtRegisterCVAR(&rt_LauncherGLContextMajor);
+    rtRegisterCVAR(&rt_LauncherGLContextMinor);
+
     rtRegisterCVAR(&rt_GameLib);
 
     rt_file_id config_fid = rtAddFile("cfg/launcher.cfg");
@@ -73,9 +86,46 @@ static void LoadGameAndRendererConfig() {
     rtProcessConfigFiles(RT_ARRAY_COUNT(fids), fids);
 }
 
+static void ParseCommandLineCVARs(int argc, char **argv) {
+    for (int i = 1; i < argc - 1; ++i) {
+        const char *name = argv[i];
+        if (name[0] != '-' || name[1] != '-')
+            continue;
+        name = &name[2];
+        rt_cvar *cvar = rtGetCVAR(name);
+        if (!cvar) {
+            ++i; /* Skip value */
+            continue;
+        }
+        const char *value = argv[i + 1];
+        
+        if (rtSetCVARFromString(cvar, value) != RT_SUCCESS) {
+            rtLog("LAUNCHER", "Failed to set %s to %s. Invalid value?", cvar->name, value);
+        }
+
+        /* Skip value */
+        ++i;
+    }
+}
+
+static char *ParseCommandLineGameLib(int argc, char **argv) {
+    char *game_lib_cmdline = NULL;
+#ifdef RT_DEBUG
+    for (int i = 1; i < argc - 1; ++i) {
+        if (strcmp(argv[i], "--game") == 0) {
+            game_lib_cmdline = argv[i + 1];
+            break;
+        }
+    }
+#endif
+    return game_lib_cmdline;
+}
+
 static void __NullGame_RegisterCVARs(void) {}
 static rt_result __NullGame_Init(void) { return RT_SUCCESS; }
 static void __NullGame_Shutdown(void) {}
+static void __NullGame_Update(rt_time_delta delta) { RT_UNUSED(delta); }
+static void __NullGame_Render(void) {}
 
 
 static rt_game_api LoadGame(const char *cmdline_gamelib) {
@@ -111,6 +161,8 @@ out:
         .RegisterCVARs = __NullGame_RegisterCVARs,
         .Init          = __NullGame_Init,
         .Shutdown      = __NullGame_Shutdown,
+        .Update        = __NullGame_Update,
+        .Render        = __NullGame_Render,
     };
 }
 
@@ -169,25 +221,26 @@ static int Entry(int argc, char **argv) {
     g_renderer.RegisterCVARs();
 
     /* Load the game */
-    const char *game_lib_cmdline = NULL;
+    const char *game_lib_cmdline = ParseCommandLineGameLib(argc, argv);
-#ifdef RT_DEBUG
-    for (int i = 1; i < argc - 1; ++i) {
-        if (strcmp(argv[i], "--game") == 0) {
-            game_lib_cmdline = argv[i + 1];
-            break;
-        }
-    }
-#endif
     rt_game_api game = LoadGame(game_lib_cmdline);
     game.RegisterCVARs();
 
     LoadGameAndRendererConfig();
+    ParseCommandLineCVARs(argc, argv);
 
     /* Create the window */
     GLFWmonitor *monitor = ChooseMonitor();
 
     GLFWwindow *window = NULL;
+    if (!rt_LauncherCreateGLContext.i) {
         glfwWindowHint(GLFW_CLIENT_API, GLFW_NO_API);
+    } else {
+        rtLog("LAUNCHER", "Creating an OpenGL %d.%d context", rt_LauncherGLContextMajor.i, rt_LauncherGLContextMinor.i);
+        glfwWindowHint(GLFW_CLIENT_API, GLFW_OPENGL_API);
+        glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, rt_LauncherGLContextMajor.i);
+        glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, rt_LauncherGLContextMinor.i);
+        glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+    }
     glfwWindowHint(GLFW_FOCUSED, GLFW_TRUE);
     glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
     glfwWindowHint(GLFW_CENTER_CURSOR, GLFW_TRUE);
@@ -239,6 +292,10 @@ static int Entry(int argc, char **argv) {
         return -1;
     }
 
+    if (rt_LauncherCreateGLContext.i) {
+        glfwMakeContextCurrent(window);
+    }
+
     /* Initialize the renderer */
     rt_renderer_init_info renderer_init_info;
 #ifdef _WIN32
@@ -268,8 +325,29 @@ static int Entry(int argc, char **argv) {
         return -1;
     }
 
+    rt_time_delta time_per_update = 1.0 / (double)rt_Framerate.f;
+    rt_timestamp previous = rtTimeNow();
+    rt_time_delta lag = time_per_update;
     while (!glfwWindowShouldClose(window)) {
         glfwPollEvents();
+
+        rt_timestamp current = rtTimeNow();
+        rt_time_delta elapsed = rtTimeBetween(previous, current);
+        previous = current;
+        lag += elapsed;
+
+        /* TODO: Process input */
+
+        while (lag >= time_per_update) {
+            game.Update(time_per_update);
+            lag -= time_per_update;
+        }
+
+        game.Render();
+        
+        if (rt_LauncherCreateGLContext.i) {
+            glfwSwapBuffers(window);
+        }
     }
 
     game.Shutdown();

src/runtime/config.c

@@ -143,38 +143,7 @@ static int Handler(void *user, const char *section, const char *name, const char
         return 1;
     }
 
-    int num_read = 0;
+    if (rtSetCVARFromString(cvar, value) != RT_SUCCESS) {
-    switch (cvar->type) {
-    case RT_CVAR_TYPE_INT:
-        num_read = sscanf(value, "%d", &cvar->i);
-        break;
-    case RT_CVAR_TYPE_FLOAT:
-        num_read = sscanf(value, "%f", &cvar->f);
-        break;
-    case RT_CVAR_TYPE_STRING: {
-        num_read   = 1;
-        char *copy = rtStoreString(value);
-        if (!copy) {
-            rtReportError("CVAR",
-                          "Failed to store string value of cvar %s in config file %s.",
-                          name,
-                          file_path);
-            return 0;
-        }
-        cvar->s = copy;
-        break;
-    }
-    case RT_CVAR_TYPE_SIZE:
-        num_read = sscanf(value, "%zu", &cvar->sz);
-        break;
-    default:
-        rtReportError("CVAR", "CVar %s has an invalid type.", cvar->name);
-        return 0;
-    }
-
-    if (num_read == 1) {
-        rtNotifyCVARChange(cvar);
-    } else {
         rtLog("CVAR", "Failed to read value of CVar %s in config file %s.", cvar->name, file_path);
     }
 
@@ -304,3 +273,39 @@ void ProcessEarlyEngineConfigs(void) {
     }
     free(buf);
 }
+
+RT_DLLEXPORT rt_result rtSetCVARFromString(rt_cvar *cvar, const char *value_str) {
+    
+    int num_read = 0;
+    switch (cvar->type) {
+    case RT_CVAR_TYPE_INT:
+        num_read = sscanf(value_str, "%d", &cvar->i);
+        break;
+    case RT_CVAR_TYPE_FLOAT:
+        num_read = sscanf(value_str, "%f", &cvar->f);
+        break;
+    case RT_CVAR_TYPE_STRING: {
+        num_read   = 1;
+        char *copy = rtStoreString(value_str);
+        if (!copy) {
+            rtReportError("CVAR",
+                          "Failed to store string value of cvar %s.",
+                          cvar->name);
+            return RT_OUT_OF_MEMORY;
+        }
+        cvar->s = copy;
+        break;
+    }
+    case RT_CVAR_TYPE_SIZE:
+        num_read = sscanf(value_str, "%zu", &cvar->sz);
+        break;
+    default:
+        rtReportError("CVAR", "CVar %s has an invalid type.", cvar->name);
+        return 0;
+    }
+
+    if (num_read == 1) {
+        rtNotifyCVARChange(cvar);
+    }
+    return (num_read) ? RT_SUCCESS : RT_INVALID_VALUE;
+}

src/runtime/config.h

@@ -57,6 +57,8 @@ RT_DLLEXPORT void rtNotifyCVARChange(const rt_cvar *cvar);
  * They are processed in-order, meaning later files can overwrite earlier files. */
 RT_DLLEXPORT rt_result rtProcessConfigFiles(unsigned int count, const rt_file_id *fids);
 
+RT_DLLEXPORT rt_result rtSetCVARFromString(rt_cvar *cvar, const char *value_str);
+
 #ifdef __cplusplus
 }
 #endif

src/runtime/timing.c

@@ -52,7 +52,7 @@ rt_result InitTiming(void) {
         rtReportError("TIMING", "Clock reports resolution greater than 1 second.");
         return RT_INVALID_VALUE;
     }
-    _gettime_freq = res.tv_nsec * 1000000000;
+    _gettime_freq = 1000000000;
     double us_res = (double)res.tv_nsec / 1e3;
     
     rtLog("TIMING", "clock_gettime resolution: %.3lf us.", us_res);