Add movement relative to time

Previously movement was based on frames rather than
time. I added time_get_dt() function for getting time
since last frame and changed rotation speed to use this
function.

Signed-off-by: Piotr Krygier <piotrkrygier@everyonecancode@xyz>

utilities/src/time_utils.c

@@ -1,9 +1,33 @@
 #include "time_utils.h"
 #include <stdint.h>
 #include "SDL3/SDL_timer.h"
+#include "commons.h"
+#include "errors_common.h"
 
 #define NS_TO_S(time) (time/1000000000)
+double g_last_time = 0.0;
+
+rse_err_t time_init(void)
+{
+    g_last_time = NS_TO_S((double)SDL_GetTicksNS());
+
+    return RSE_ERROR_NO_ERROR;
+}
+
 double time_get_sec_from_start(void)
 {
     return NS_TO_S((double)SDL_GetTicksNS());
 }
+
+void time_update(void)
+{
+    g_last_time = NS_TO_S((double)SDL_GetTicksNS());
+}
+
+double time_get_dt(void)
+{
+    float time = NS_TO_S((double)SDL_GetTicksNS());
+    float dt = time - g_last_time;
+
+    return dt;
+}

utilities/time_utils.h

@@ -12,6 +12,13 @@
 #ifndef TIME_UTILS_H_
 #define TIME_UTILS_H_
 
+#include "commons.h"
+
+rse_err_t time_init(void);
+void time_update(void);
+
 double time_get_sec_from_start(void);
 
+double time_get_dt(void);
+
 #endif // !TIME_UTILS_H_