Polygon Object

Table of Contents

• GD::Polygon.new
• addPt
• toPt
• getPt
• setPt
• deletePt
• length
• vertices
• bounds
• offset
• map
• scale
• transform

• GD::Polygon.new

  function

  create polygon object

  format

  polygon = GD::Polygon.new

  source

  poly = GD::Polygon.new
  

  output

  Nothing

• addPt

  function

  add point (x,y) to the polygon

  format

  polygon.addPt(x, y)

  source

  poly = GD::Polygon.new
  
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  

  output

  Nothing

• toPt

  function

  add point (x + dx, y + dy) to the polygon using relative (dx,dy) coordinates. If this is the first point, act like addPt().

  format

  polygon.toPt(dx, dy)

  source

  poly = GD::Polygon.new
  
  poly.addPt(100,50)
  poly.toPt(-50,50)
  poly.toPt(100,0)
  

  output

  Nothing

• getPt

  function

  return the point at the specified vertex

  format

  x, y = polygon.getPt(n)

  source | polygon_getPt.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  
  x, y = poly.getPt(0)
  STDERR.print "Point 0  x: ", x, "  y: ", y, "\n"
  x, y = poly.getPt(1)
  STDERR.print "Point 1  x: ", x, "  y: ", y, "\n"
  x, y = poly.getPt(2)
  STDERR.print "Point 2  x: ", x, "  y: ", y, "\n"
  
  im.polygon(poly, blue)
  

  output

  

  Point 0  x: 100  y: 50
  Point 1  x: 50  y: 100
  Point 2  x: 150  y: 100
  

• setPt

  function

  change the value of an already existing vertex

  format

  polygon.setPt(n, x, y)

  source | polygon_setPt.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(100,150)
  poly.setPt(2, 150,100)
  
  im.polygon(poly, blue)
  

  output

  

• deletePt

  function

  delete the specified vertex

  format

  polygon.deletePt(n)

  source | polygon_deletePt.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(100,150)
  poly.addPt(150,100)
  poly.deletePt(3)
  
  im.polygon(poly, blue)
  

  output

  <--- delete

• length

  function

  return the number of vertices in the polygon

  format

  all_points = polygon.length

  source | polygon_length.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  
  STDERR.print "length: ", poly.length, "\n"
  im.polygon(poly, blue)
  

  output

  length: 3
  

• vertices

  function

  return a list of all the verticies in the polygon object

  format

  xs = polygon.vertices

  source | polygon_vertices.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  
  im.polygon(poly, blue)
  
  xs = poly.vertices
  for i in xs
    STDERR.print "(", i[0], " , ", i[1], ")", "\n"
  end
  

  output

  (100 , 50)
  (50 , 100)
  (150 , 100)
  

• bounds

  function

  return the smallest rectangle that completely encloses the polygon

  format

  x1, y1, x2, y2 = polygon.bounds

  source | polygon_bounds.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  
  x1, y1, x2, y2 = poly.bounds
  STDERR.print "x1: ", x1, "  y1: ", y1,
    "  x2: ", x2, "  y2: ", y2, "\n"
  
  poly.addPt(150,100)
  
  x1, y1, x2, y2 = poly.bounds
  STDERR.print "x1: ", x1, "  y1: ", y1,
    "  x2: ", x2, "  y2: ", y2, "\n"
  
  im.polygon(poly, blue)
  

  output

  

  x1: 50  y1: 50  x2: 100  y2: 100
  x1: 50  y1: 50  x2: 150  y2: 100
  

• offset

  function

  offset all the vertices of the polygon

  format

  polygon.offset(vx, vy)

  source | polygon_offset.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  im.polygon(poly, blue)
  
  poly.offset(25, 75)
  im.polygon(poly, blue)
  

  output

  

• map

  function

  map the polygon from a source rectangle to an equivalent position in a destination rectangle

  format

  polygon.map(sx1, sy1, sx2, sy2, x1, y1, x2, y2)

  source | polygon_map.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  im.polygon(poly, blue)
  
  poly.map(50, 50, 150, 100, 75, 100, 125, 150)
  im.polygon(poly, red)
  

  output

  

• scale

  function

  scale each vertex of the polygon

  format

  polygon.scale(sx,sy)

  source | polygon_scale.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  im.polygon(poly, blue)
  
  poly.scale(0.5, 0.5)
  im.polygon(poly, red)
  

  output

  

  note

  later GD-0.6.2

• transform

  function

  run each vertex of the polygon through a transformation matrix

  format

  polygon.transform(sx,rx,ry,sy,tx,ty)
  sx and sy are the X and Y scaling factors, rx and ry are the X and Y rotation factors, tx and ty are the X and Y offsets.
  sx * x + rx * y + tx, ry * x + sy * y + ty

  source | polygon_transform.rb

  poly = GD::Polygon.new
  poly.addPt(100,50)
  poly.addPt(50,100)
  poly.addPt(150,100)
  im.polygon(poly, blue)
  
  # scale
  poly.transform(0.5,0,0,0.5,0,0)
  im.polygon(poly, red)
  
  poly.transform(2,0,0,2,30,50)
  im.polygon(poly, green)
  

  output

  

  note

  later GD-0.6.2