两点之间的距离问题

灯笼菜刀王

我知道两点之间的距离公式  √((x1-x2)^2 + (y1-y2)^2

但是以该值作为宽度 m = Math.sqrt((x1 - x2).abs^2 + (y1 - y2).abs^2)   描绘线条却短很多很多....


而用 m = (x1-x2).abs + (y1-y2).abs 来作为宽度, 却会长很多


请问, 正确公式该怎么做呢?

RUBY 代码复制

x,y = 111,333
back = RPG::Sprite.new
  back.bitmap = Bitmap.new(640,480)
back.bitmap.fill_rect(0,0,640,480,Color.new(0,0,0))
  a = RPG::Sprite.new
  b = RPG::Sprite.new
  c = RPG::Sprite.new
  bbb = Bitmap.new(10,10)
  bbb.fill_rect(0,0,10,10,Color.new(0,255,255)) 
  a.bitmap = b.bitmap = bbb
  a.set_xy(320,240)
  b.set_xy(x,y)
  c.set_xy(320,240)
  #m = Math.sqrt((x - 320).abs^2 + (y - 240).abs^2)
  m = (x-320).abs + (y-240).abs
  c.bitmap = Bitmap.new(m,1)
  c.bitmap.fill_rect(0,0,m,1,Color.new(255,255,255)) 
  d = Math.atan((240-y).abs.to_f/(320-x).abs) / Math::PI * 180
  if x < 320 and y > 240 #第三象限
    r = -180
  elsif x < 320 and y < 240 #第一象限
    r = 90
  elsif x > 320 and y < 240 #第四象限
    r = -90
  else 
    r = 0
  end
  c.angle = d + r

x,y = 111,333


back = RPG::Sprite.new


  back.bitmap = Bitmap.new(640,480)


back.bitmap.fill_rect(0,0,640,480,Color.new(0,0,0))


  a = RPG::Sprite.new


  b = RPG::Sprite.new


  c = RPG::Sprite.new


  bbb = Bitmap.new(10,10)


  bbb.fill_rect(0,0,10,10,Color.new(0,255,255)) 


  a.bitmap = b.bitmap = bbb


  a.set_xy(320,240)


  b.set_xy(x,y)


  c.set_xy(320,240)


  #m = Math.sqrt((x - 320).abs^2 + (y - 240).abs^2)


  m = (x-320).abs + (y-240).abs


  c.bitmap = Bitmap.new(m,1)


  c.bitmap.fill_rect(0,0,m,1,Color.new(255,255,255)) 


  d = Math.atan((240-y).abs.to_f/(320-x).abs) / Math::PI * 180


  if x < 320 and y > 240 #第三象限


    r = -180


  elsif x < 320 and y < 240 #第一象限


    r = 90


  elsif x > 320 and y < 240 #第四象限


    r = -90


  else 


    r = 0


  end


  c.angle = d + r

PS: 单纯两点之间画线从雷达图脚本里学到了,它用的是在直线距离上每一个点描绘, 然而我现在想要的是,两点之间连接一张图片, 图片的宽度 = 两点之间的距离, 所以那种方法没办法用~~~