I'm currently working on a mini map for a game in which keeps track of different items of importance on and off the screen. When I first created the mini map through a secondary camera rendered onto a texture and displayed on screen in a miniature display, it was rectangle shape. I was able to ensure when the item of importance left the view of the map, an arrow pointing to the target showed up and remained on the edge of the map. It was basically clamping the x & y positions of the arrow to half the camera view's width and length (with some suitable margin space).
Anyway. Now I am trying to make the mini map circular and while I have the proper render mask on to guarantee that shape of the mini map, I am having difficulties in clamping the arrows to the shape of the new mini-map. In the rectangular mini map, the arrows stayed in the corners while clamped, but obviously, circles don't have corners.
I am thinking clamping the arrow's x & y positions have to do with the radius of the circle (half of the height of the screen/minimap), but because I'm a little weak on the math side, I am kindly requesting some help. How would I clamp the arrows to the edge of a new circle shape?
The code I have now is as follows:
let {width: canvasWidth, height: canvasHeight} = cc.Canvas.instance.node, // 960, 640
targetScreenPoint = cc.Camera.main.getWorldToScreenPoint(this.targetNode.position)
// other code for rotation of arrow, etc...
// FIXME: clamp the the edge of the minimap mask which is circular
// This is the old clamping code for a rectangle shape.
let arrowPoint = targetScreenPoint;
arrowPoint.x = utils.clamp(arrowPoint.x, (-canvasWidth / 2) + this.arrowMargin,
(canvasWidth / 2) - this.arrowMargin);
arrowPoint.y = utils.clamp(arrowPoint.y, (-canvasHeight / 2) + this.arrowMargin,
(canvasHeight /2) - this.arrowMargin);
this.node.position = cc.v2(arrowPoint.x, arrowPoint.y);
I should probably also note that all mini-map symbols and arrows technically are on screen but only are displayed in on the secondary camera through a culling mask... you know, just in case it helps.
Just for anyone else looking to do the same, I basically normalized the direction from the target node that the arrow points at and multiplied it by the radius of the image mask (with appropriate margin space).
Since the player node and the centre of the mask is at origin, I just got the difference from the player. The (640/2) is the diameter, which of course, shouldn't be hardcoded, but meh for now. Thanks to those who commented and got me thinking in the right direction.
let direction = this.targetNode.position.sub(this.playerNode.position).normalize();
let arrowPos = direction.mul((640/2) - this.arrowMargin);
this.node.position = arrowPos;