set ctx.frame_duration

src/twn_loop.c

@@ -532,6 +532,7 @@ static bool initialize(void) {
     ctx.desired_frametime = ctx.clocks_per_second / ctx.ticks_per_second;
     ctx.frame_accumulator = 0;
     ctx.game.frame_number = 0;
+    ctx.game.frame_duration = 1.0f / (float)ctx.ticks_per_second;
 
     /* delta time averaging */
     ctx.delta_averager_residual = 0;