update gametime to be less heavy and more flexible

src/game/game.c

@@ -5,17 +5,31 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <time.h>
 
 #include "gametime.h"
 
-void game_init(gamedata* dat, gametime* gt) {
+void game_init(gamedata* dat) {
+	// initialize the game time
+	struct gametime gt = {{0}, 0};
+	gametime_get(&gt.ts);
+
+	// initialize the game data
 	*dat = (gamedata){
 		gt,
 		true,
 	};
 }
 
+static inline void update_gametime(gamedata* dat) {
+	struct timespec ts;
+	gametime_get(&ts);
+	dat->time.delta = (ts.tv_sec - dat->time.ts.tv_sec) + (ts.tv_nsec - dat->time.ts.tv_nsec) * 1e-9;
+	dat->time.ts = ts;
+}
+
 void game_update(gamedata* dat) {
+	update_gametime(dat); // update the game time
 	uint8_t const* keys = SDL_GetKeyboardState(NULL);
 
 	if (keys[SDL_SCANCODE_ESCAPE])

src/game/game.h

@@ -12,10 +12,10 @@
 #define TAUf (M_PIf * 2.0F) // τ constant as a 32-bit floating point
 
 typedef struct {
-	gametime* time;
+	struct gametime time;
 	bool run;
 } gamedata;
 
-void game_init(gamedata*, gametime*);   // initializes everything needed to start the game; outputs to game_data
+void game_init(gamedata*);   // initializes everything needed to start the game; outputs to game_data
 void game_update(gamedata*); // causes an update to occur within the game
 void game_free(gamedata*);   // frees the resources associated with the game

src/game/gametime.h

@@ -1,39 +1,24 @@
 #pragma once
-
 #include <time.h>
 
-#include "../util/attributes.h"
-
-typedef struct {
-	struct timespec ts; // stores the time at the current update
-	double sec;         // stores the current time in seconds
-	float scale;        // multiplier for the time calculation, default value is 1.0
-	float delta;        // the time that it took between updates
-} gametime;
-
-// initializes the gametime struct
-atrb_const static inline gametime gametime_new(void) {
+struct gametime {
 	struct timespec ts;
-	timespec_get(&ts, TIME_UTC);
+	float delta;
+};
 
-	return (gametime){
-		ts,
-		0.0,
-		1.0F,
-		0.0F,
-	};
+#if _POSIX_C_SOURCE >= 199309L
+static inline void gametime_get(struct timespec* ts) {
+	clock_gettime(CLOCK_MONOTONIC, ts);
 }
-
-// updates the internal variables
-static inline void gametime_update(gametime* gt) {
-	struct timespec ts;
-	timespec_get(&ts, TIME_UTC);
-	gt->sec = (double)ts.tv_nsec * 1e-9 + ts.tv_sec;                        // calculate the current time in seconds
-	gt->delta = ((double)(ts.tv_nsec - gt->ts.tv_nsec) * 1e-9) * gt->scale; // calculate how much time has passed between this and last frame
-	gt->ts = ts;                                                            // update the game's timespec
-}
-
-// gets how many times the game updates per second
-atrb_const static inline float gametime_get_ups(gametime const* gt) {
-	return 1.0F / gt->delta;
+#elif defined _WIN32
+# include <windows.h>
+static inline void gametime_get(struct timespec* ts) {
+	LARGE_INTEGER cnt, frq;
+	QueryPerformanceCounter(&cnt);
+	QueryPerformanceFrequency(&frq);
+	ts->tv_sec = (time_t)(cnt.QuadPart / frq.QuadPart);
+	ts->tv_nsec = (time_t)((cnt.QuadPart % frq.QuadPart) * 1000000000 / frq.QuadPart);
 }
+#else
+# error platform not supported
+#endif

src/main.c

@@ -5,11 +5,9 @@
 
 #include "error.h"
 #include "game/game.h"
-#include "game/gametime.h"
 #include "window/render.h"
 
 // initialized in init(), reading beforehand is undefined behaviour
-static gametime gt;
 static gamedata gdat;
 static renderdata rdat;
 
@@ -20,8 +18,7 @@ static void init(void) {
 		fatal(ERROR_SDL_INIT, __FILE_NAME__, __LINE__, "SDL could not initialize! SDL Error: %s", SDL_GetError());
 
 	// initialize other game components
-	gt = gametime_new();
-	game_init(&gdat, &gt);
+	game_init(&gdat);
 	render_init(&rdat, &gdat);
 }
 
@@ -40,7 +37,6 @@ static void update(void) {
 	}
 
 	// perform updates
-	gametime_update(&gt);
 	game_update(&gdat);
 	render_update(&rdat);
 }