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[tip] WorldToScreenPoint function

A topic by Liam Brocklehurst created Feb 22, 2016 Views: 216
Viewing posts 1 to 1

I recently needed to get the screen position of a player for checks to move the camera, so I added some functions to allow me to do this - figured it might help someone else! If anyone spots any errors, let me know and I can update. I imagine this'll only work for 2D games!


Firstly, I created a class that could hold top, bottom, left, right bounds (reusable for a few things):

class Bounds
{
  constructor(public top: number, public bottom: number, public left: number, public right: number) { }
}

We can then use this within our CameraHelper class:

class CameraHelper {
  
  static WorldToScreenPoint(x: number, y: number, cameraName: string): Sup.Math.Vector2
  {
    let cameraActor = Sup.getActor(cameraName);
    let cameraPos = cameraActor.getPosition();
    let cameraBounds = CameraHelper.CameraBounds(cameraName);
    
    return new Sup.Math.Vector2(
      (x - cameraBounds.left) / Sup.Game.getScreenRatio().width,
      (y - cameraBounds.bottom) / Sup.Game.getScreenRatio().height
    );
  }
  static CameraBounds(cameraName: string): Bounds
  {
    let cameraActor = Sup.getActor(cameraName);
    let cameraPos = cameraActor.getPosition();
    return new Bounds
    (
      cameraPos.y + (Sup.Game.getScreenRatio().height / 2),
      cameraPos.y - (Sup.Game.getScreenRatio().height / 2),
      cameraPos.x - (Sup.Game.getScreenRatio().width / 2),
      cameraPos.x + (Sup.Game.getScreenRatio().width / 2)
    );
  }
}

CameraBounds returns a Bounds type of the world position of the top, bottom, left and right of the camera. WorldToScreenPoint then takes these values and determines what screen point (0-1) the x,y parameters are at.

Sup.Game.getScreenRatio() is possibly not giving us accurate calculations, so if I find a better way (or if someone lets me know) I'll get that changed.

Hope this helps someone!