diff --git a/leenkx/Sources/iron/system/Time.hx b/leenkx/Sources/iron/system/Time.hx
index 7b6cd22..99484eb 100644
--- a/leenkx/Sources/iron/system/Time.hx
+++ b/leenkx/Sources/iron/system/Time.hx
@@ -8,21 +8,23 @@ class Time {
 		return 1 / frequency;
 	}
 	
-	// TODO: set physics step from Blender's editor
+	static var _fixedStep: Null<Float>;
 	public static var fixedStep(get, never): Float;
 	static function get_fixedStep(): Float {
-		return 1 / 60;
+		return _fixedStep;
 	}
 	
-	public static var scale = 1.0;
-	public static var delta(get, never): Float;
-	static function get_delta(): Float {
-		if (frequency == null) initFrequency();
-		return (1 / frequency) * scale;
+
+	public static function initFixedStep(value: Float = 1 / 60) {
+		_fixedStep = value;
 	}
 
-	static var last = 0.0;
-	public static var realDelta = 0.0;
+
+	static var lastTime = 0.0;
+	public static var delta = 0.0;
+
+	static var lastRenderTime = 0.0;
+	public static var renderDelta = 0.0;
 	public static inline function time(): Float {
 		return kha.Scheduler.time();
 	}
@@ -37,7 +39,12 @@ class Time {
 	}
 
 	public static function update() {
-		realDelta = realTime() - last;
-		last = realTime();
+		delta = (realTime() - lastTime) * scale;
+		lastTime = realTime();
+	}
+
+	public static function render() {
+		renderDelta = (realTime() - lastRenderTime) * scale;
+		lastRenderTime = realTime();
 	}
 }