Polygon

Introduction

Polygon shape and methods, built-in methods of phaser.

• Author: Richard Davey

Usage

Create shape

var polygon = new Phaser.Geom.Polygon(points);

• points :
  • An array of number : [x0, y0, x1, y1, ...]
  • An array of points : [{x:x0, y:y0}, {x:x1, y:y1}, ...]
  • A string : 'x0 y0 x1 y1 ...'

Clone shape

var polygon1 = Phaser.Geom.Polygon.Clone(polygon0);

Draw on graphics

• Fill shape

  // graphics.fillStyle(color, alpha);   // color: 0xRRGGBB
  graphics.fillPoints(polygon.points, true);
  

• Stroke shape

  // graphics.lineStyle(lineWidth, color, alpha);   // color: 0xRRGGBB
  graphics.strokePoints(polygon.points, true);
  

Set properties

polygon.setTo(points);
// points = [x0, y0, x1, y1, x2, y2, ...] , or [{x,y}, {x,y}, {x,y}, ...]

Get properties

• Points

  var points = polygon.points;    // array of points {x,y}
  

• Area

  var area = polygon.area;
  

• Number array

  var out = Phaser.Geom.Polygon.GetNumberArray(polygon);
  // var out = Phaser.Geom.Polygon.GetNumberArray(polygon, out);  // modify out
  

  • arr : [x0, y0, x1, y1, x2, y2, ...]
• AABB (A minimum rectangle to cover this polygon)

  var out = Phaser.Geom.Polygon.GetAABB(polygon);
  // var out = Phaser.Geom.Polygon.GetAABB(polygon, out);
  

  • out : A rectangle object
• Type:

  var type = polygon.type; // 4
  

Point(s) & shape

• Point is inside shape

  var isInside = polygon.contains(x, y);
  

  or

  var isInside = Phaser.Geom.Polygon.ContainsPoint(polygon, point);
  

• Translate : Shift points.

  Phaser.Geom.Polygon.Translate(polygon, x, y);
  

• Reverse the order of points.

  var polygon = Phaser.Geom.Polygon.Reverse(polygon);
  

• Smooth : Takes a Polygon object and applies Chaikin's smoothing algorithm on its points.

  Phaser.Geom.Polygon.Smooth(polygon)
  

• Simplify : Simplifies the points by running them through a combination of Douglas-Peucker and Radial Distance algorithms. Simplification dramatically reduces the number of points in a polygon while retaining its shape, giving a huge performance boost when processing it and also reducing visual noise.

  var polygon = Phaser.Geom.Polygon.Simplify(polygon);
  // var polygon = Phaser.Geom.Polygon.Simplify(polygon, tolerance, highestQuality);
  

Vector to polygon

• Get closest point of intersection between a vector and an array of polygons

  var result = Phaser.Geom.Intersects.GetLineToPolygon(line, polygons);
  // var out = Phaser.Geom.Intersects.GetLineToPolygon(line, polygons, isRay, out);
  

  • line : Vector of line object
  • polygons : A single polygon, or array of polygons
  • isRay : Is line a ray or a line segment?
  • out :
    • out.x, out.y : Intersection point
    • out.z : Closest intersection distance
    • out.w : Index of the polygon
• Projects rays out from the given point to each line segment of the polygons.

  var out = Phaser.Geom.Intersects.GetRaysFromPointToPolygon(x, y, polygons);
  

  • x, y : The point to project the rays from.
  • polygons : A single polygon, or array of polygons
  • out : An array containing all intersections
    • out[i].x, out[i].y : Intersection point
    • out[i].z : Angle of intersection
    • out[i].w : Index of the polygon