improve duration calculation for go_to and arc_drawing

turtle-lib-macroquad/src/drawing.rs

@@ -267,8 +267,11 @@ fn draw_tween_arc(
         direction,
     );
 
-    // Debug: draw center
-    draw_circle(geom.center.x, geom.center.y, 5.0, GRAY);
+    // Debug: draw center using Lyon tessellation
+    if let Ok(mesh_data) = crate::tessellation::tessellate_circle(geom.center, 5.0, GRAY, true, 1.0)
+    {
+        draw_mesh(&mesh_data.to_mesh());
+    }
 
     // Calculate how much of the arc we've traveled based on tween progress
     // Use the same eased progress as the turtle position for synchronized animation
@@ -278,20 +281,18 @@ fn draw_tween_arc(
     let angle_traveled = total_angle.to_radians() * progress;
     let (rotation_degrees, arc_degrees) = geom.draw_arc_params_partial(angle_traveled);
 
-    // Adjust radius inward by half the line width so the line sits on the turtle's path
-    let draw_radius = radius - tween.start_state.pen_width / 2.0;
-
-    // Draw the partial arc
-    draw_arc(
-        geom.center.x,
-        geom.center.y,
-        steps as u8,
-        draw_radius,
+    // Use Lyon to tessellate and draw the partial arc
+    if let Ok(mesh_data) = crate::tessellation::tessellate_arc(
+        geom.center,
+        radius,
         rotation_degrees,
-        tween.start_state.pen_width,
         arc_degrees,
         tween.start_state.color,
-    );
+        tween.start_state.pen_width,
+        steps,
+    ) {
+        draw_mesh(&mesh_data.to_mesh());
+    }
 }
 
 /// Draw the turtle shape

turtle-lib-macroquad/src/execution.rs

@@ -58,7 +58,7 @@ pub fn execute_command(command: &TurtleCommand, state: &mut TurtleState, world:
                     arc_degrees,
                     state.color,
                     state.pen_width,
-                    *steps as u8,
+                    *steps,
                 ) {
                     world.add_command(DrawCommand::Mesh(mesh_data));
                 }
@@ -248,7 +248,7 @@ pub fn add_draw_for_completed_tween(
                     arc_degrees,
                     start_state.color,
                     start_state.pen_width,
-                    *steps as u8,
+                    *steps,
                 ) {
                     world.add_command(DrawCommand::Mesh(mesh_data));
                 }

turtle-lib-macroquad/src/tessellation.rs

@@ -266,7 +266,7 @@ pub fn tessellate_arc(
     arc_angle_degrees: f32,
     color: Color,
     stroke_width: f32,
-    segments: u8,
+    segments: usize,
 ) -> Result<MeshData, Box<dyn std::error::Error>> {
     // Build arc path manually from segments
     let mut builder = Path::builder();

turtle-lib-macroquad/src/tweening.rs

@@ -419,7 +419,7 @@ impl TweenController {
             }
 
             let speed = state.speed; // Extract speed before borrowing self
-            let duration = self.calculate_duration(&command_clone, speed);
+            let duration = self.calculate_duration_with_state(&command_clone, state, speed);
 
             // Calculate target state
             let target_state = self.calculate_target_state(state, &command_clone);
@@ -477,7 +477,12 @@ impl TweenController {
         )
     }
 
-    fn calculate_duration(&self, command: &TurtleCommand, speed: AnimationSpeed) -> f64 {
+    fn calculate_duration_with_state(
+        &self,
+        command: &TurtleCommand,
+        current: &TurtleState,
+        speed: AnimationSpeed,
+    ) -> f64 {
         let speed = speed.value();
 
         let base_time = match command {
@@ -490,9 +495,12 @@ impl TweenController {
                 let arc_length = radius * angle.to_radians().abs();
                 arc_length / speed
             }
-            TurtleCommand::Goto(_target) => {
-                // Calculate distance (handled in calculate_target_state)
-                0.1 // Placeholder, will be calculated properly
+            TurtleCommand::Goto(target) => {
+                // Calculate actual distance from current position to target
+                let dx = target.x - current.position.x;
+                let dy = target.y - current.position.y;
+                let distance = (dx * dx + dy * dy).sqrt();
+                distance / speed
             }
             _ => 0.0, // Instant commands
         };