SFML community forums

Help => Graphics => Topic started by: rokstars on January 19, 2016, 10:29:16 am

Title: Layers and camera
Post by: rokstars on January 19, 2016, 10:29:16 am

Hello.
I'm using .Net version of SFML, but it doesnt matter, right?)
So, here is what i did:

(click to show/hide)

public class Layer : Drawable
    {
        private string name;
        private List<Drawable> list;
        private View view;

        public Layer(string name, View copyView)
        {
            this.name = name;
            list = new List<Drawable>();
            view = new View(copyView);
        }

        public void Add(Drawable drawable) { list.Add(drawable); }

        public void Remove(Drawable drawable) { list.Remove(drawable); }

        public void Draw(RenderTarget target, RenderStates states)
        {
            target.SetView(view);
            for (int i = 0; i < list.Count; i++)
                target.Draw(list[i], states);
        }

        public void SetPosition(float x, float y)
        {
            var offset = new Vector2f(view.Center.X - x, view.Center.Y - y);
            view.Move(offset);
        }

        public void SetPosition(Vector2f position)
        {
            var offset = view.Center - position;
            view.Move(offset);
        }

        public void Move(Vector2f offset)
        {
            SetPosition(view.Center + offset);
        }

        public View GetView() { return view; }

        public string Name
        {
            get { return name; }
            set { name = value; }
        }
    }

(click to show/hide)

    public class LayersHandler : Drawable
    {
        private Dictionary<string, Layer> layers;
        private View view;

        public LayersHandler(View view)
        {
            layers = new Dictionary<string, Layer>();
            this.view = view;
        }

        public void AddLayers(params string[] names)
        {
            for (int i = 0; i < names.Length; i++)
                AddLayer(names[i]);
        }

        public void RemoveLayers(params string[] names)
        {
            for (int i = 0; i < names.Length; i++)
                RemoveLayer(names[i]);
        }

        public void AddLayer(string name)
        {
            layers.Add(name, new Layer(name, view));
        }

        public void RemoveLayer(string name)
        {
            layers.Remove(name);
        }

        public void AddToLayer(string name, Drawable drawable)
        {
            layers[name].Add(drawable);
        }

        public void RemoveFromLayer(string name, Drawable drawable)
        {
            layers[name].Remove(drawable);
        }

        public void Draw(RenderTarget target, RenderStates states)
        {
            foreach (var el in layers)
                target.Draw(el.Value);
        }

        public Layer GetLayer(string name)
        {
            return layers[name];
        }
    }

(click to show/hide)

    class Camera
    {
        private FloatRect bounds;

        private Vector2f size;
        private Vector2f center;

        private float x;
        private float y;

        private List<View> views;
        private Transformable followingObject;

        public Camera()
        {
            views = new List<View>();
        }

        public void Bind(Layer layer)
        {
            views.Add(layer.GetView());
            size = views[0].Size;
            center = views[0].Center;
            x = views[0].Center.X;
            y = views[0].Center.Y;
        }

        public void MoveViews(Vector2f offset)
        {
            for (int i = 0; i < views.Count; i++)
                views[i].Move(offset);
        }

        public void SetViewsCenter(Vector2f center)
        {
            for (int i = 0; i < views.Count; i++)
                views[i].Center = center;
        }

        public void ScrollToXY(float x, float y)
        {
            float xx = x;
            float yy = y;
            if (bounds != null)
            {
                xx = eMath.clamp(xx, bounds.Left + size.X / 2, bounds.Left - size.X / 2 + bounds.Width);
                yy = eMath.clamp(yy, bounds.Top + size.Y / 2, bounds.Top - size.Y / 2 + bounds.Height);
            }

            xx = eMath.lerp(this.x, xx, 0.002f);
            yy = eMath.lerp(this.y, yy, 0.002f);

            SetViewsCenter(new Vector2f(xx, yy));
            this.x = xx;
            this.y = yy;
        }

        public void Update()
        {
            if (followingObject != null)
                ScrollToXY(followingObject.Position.X, followingObject.Position.Y);
        }

        public void Follow(Transformable obj)
        {
            followingObject = obj;
        }

        public void SetBounds(FloatRect bounds)
        {
            this.bounds = bounds;
        }
    }

And usage:

//creating window, sprites and etc.
layers = new LayersHandler(window.GetView());
// creating 2 layers
layers.AddLayers("bottom", "mid", "UI");
// adding drawable objects
layers.AddToLayer("bottom", sprite);
layers.AddToLayer("bottom", shape);
layers.AddToLayer("mid", shape2);
layers.AddToLayer("UI", TextField);

cam = new Camera();
// Camera will scroll layer "bottom" and "mid"
cam.Bind(layers.GetLayer("bottom"));
cam.Bind(layers.GetLayer("mid"));
cam.Follow(shape);
cam.SetBounds(new FloatRect(0, 0, 1920, 1080));

//Game loop
while (window.IsOpen)
{
   cam.Update();
   window.Clear(Color.White);
   window.Draw(layers);
   window.Display();
}
 

Sorry for lot of code, but its not hard to understand whats going on here.
I want to scroll a specific layers, but others should stay at (0, 0). I also want to emlement paralax effect to some layers, but first of all i need to know: is this method OK or is it realy bad and there is a better way to do all that stuff?

P.S. Sorry for bad english.

Title: Re: Layers and camera
Post by: mkalex777 on January 20, 2016, 10:47:38 pm

I think it will be better to incapsulate view inside layer implementation. It's too hard to read the code. I used layered rendering with sfml in the following way:

foreach(var layer in _layers)
   layer.Draw(renderTarget);

each layer know how to render itself. For example, here is how Layer.Draw is implemented:
public void Draw(RenderTarget target)
{
   target.SetView(_view);
   foreach(var item in _items)
      DrawItem(target, item);
...