//set up the surface

public Surface SurfaceLighting = new Surface(Game.Instance.Width, Game.Instance.Height, new Color("379")) {

    Blend = BlendMode.Multiply

};



//set up the light

public Image ImageLight = new Image(Assets.ImageLight1) {

    Blend = BlendMode.Add

};



//add the surface to an entity to render it

//this happens in an object's initialization

AddGraphicGUI(SurfaceLighting);



//render light to the surface

//this happens in a Render() function

Draw.SetTarget(SurfaceLighting);

ImageLight.Color = Color.White;

Draw.Graphic(ImageLight, Input.MouseX, Input.MouseY);

ImageLight.Color = Color.Red;

Draw.Graphic(ImageLight, Input.MouseX + 500, Input.MouseY);

ImageLight.Color = Color.Blue;

Draw.Graphic(ImageLight, Input.MouseX - 500, Input.MouseY);

Draw.ResetTarget();

using Otter;

using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;



namespace CoroutineExample {

    class CoroutineScene : Scene {



        public Image ImageBox = Image.CreateRectangle(50);



        public Color NextColor = Color.White;

        public Color CurrentColor = Color.White;



        public CoroutineScene() : base() {

            // Center that box.

            ImageBox.CenterOrigin();



            // Gotta draw the box.

            AddGraphic(ImageBox);



            // Set the box position.

            ImageBox.X = 100;

            ImageBox.Y = 100;

        }



        public override void Begin() {

            base.Begin();



            // Start the coroutine, yo.

            Game.Coroutine.Start(MainRoutine());

        }



        /// <summary>

        /// The main coroutine to execute.  This will move the box around and change its color.

        /// </summary>

        /// <returns>Whatever a coroutine thing returns.  Sometimes 0 I guess.</returns>

        IEnumerator MainRoutine() {

            // Wait for 30 frames.

            yield return Coroutine.Instance.WaitForFrames(30);

            // Set the next color.

            NextColor = Color.Red;

            // Move the box to the top right.

            yield return MoveBoxTo(540, 100);



            // Wait for 30 frames.

            yield return Coroutine.Instance.WaitForFrames(30);

            // Set the next color.

            NextColor = Color.Yellow;

            // Move the box to the bottom right.

            yield return MoveBoxTo(540, 380);



            // Wait for 30 frames.

            yield return Coroutine.Instance.WaitForFrames(30);

            // Set the next color.

            NextColor = Color.Green;

            // Move the box to the bottom left.

            yield return MoveBoxTo(100, 380);



            // Wait for 30 frames.

            yield return Coroutine.Instance.WaitForFrames(30);

            // Set the next color.

            NextColor = Color.Cyan;

            // Move the box to the top left.

            yield return MoveBoxTo(100, 100);

            

            // Start a new coroutine.

            Game.Coroutine.Start(MainRoutine());

        }



        IEnumerator MoveBoxTo(float x, float y) {

            // Used to determine the completion.

            var initialDistance = Util.Distance(ImageBox.X, ImageBox.Y, x, y);



            float currentDistance = float.MaxValue;

            while (currentDistance > 1) {

                currentDistance = Util.Distance(ImageBox.X, ImageBox.Y, x, y);



                // Determine the completion of the movement from 0 to 1.

                var completion = Util.ScaleClamp(currentDistance, 0, initialDistance, 1, 0);



                // Lerp the color of the box.

                ImageBox.Color = Util.LerpColor(CurrentColor, NextColor, completion);



                // Spin the box along with its movement.

                ImageBox.Angle = Util.ScaleClamp(completion, 0, 1, 0, 360);



                // Actually move the box.

                ImageBox.X = Util.Approach(ImageBox.X, x, 5);

                ImageBox.Y = Util.Approach(ImageBox.Y, y, 5);



                // Wait until next frame.

                yield return 0;

            }



            // Done moving.  Update the color.

            CurrentColor = NextColor;

        }

    }

}