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80 lines
3 KiB
CoffeeScript
80 lines
3 KiB
CoffeeScript
class LineSegment
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@className: "LineSegment"
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constructor: (@a, @b) ->
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@slope = (@a.y - @b.y) / (@a.x - @b.x)
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@y0 = @a.y - (@slope * @a.x)
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@left = if @a.x < @b.x then @a else @b
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@right = if @a.x > @b.x then @a else @b
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@bottom = if @a.y < @b.y then @a else @b
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@top = if @a.y > @b.y then @a else @b
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y: (x) ->
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(@slope * x) + @y0
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x: (y) ->
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(y - @y0) / @slope
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intersectsLineSegment: (lineSegment) ->
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if lineSegment.slope is @slope
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if lineSegment.y0 is @y0
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if lineSegment.left.x is @left.x or lineSegment.left.x is @right.x or lineSegment.right.x is @right.x or lineSegment.right.x is @left.x
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# segments are of the same line with shared start and/or end points
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return true
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else
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[left, right] = if lineSegment.left.x < @left.x then [lineSegment, @] else [@, lineSegment]
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if left.right.x > right.left.x
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# segments are of the same line and one is contained within the other
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return true
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else if Math.abs(@slope) isnt Infinity and Math.abs(lineSegment.slope) isnt Infinity
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x = (lineSegment.y0 - @y0) / (@slope - lineSegment.slope)
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if x >= @left.x and x <= @right.x and x >= lineSegment.left.x and x <= lineSegment.right.x
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return true
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else if Math.abs(@slope) isnt Infinity or Math.abs(lineSegment.slope) isnt Infinity
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[vertical, nonvertical] = if Math.abs(@slope) isnt Infinity then [lineSegment, @] else [@, lineSegment]
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x = vertical.a.x
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bottom = vertical.bottom.y
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top = vertical.top.y
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y = nonvertical.y(x)
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left = nonvertical.left.x
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right = nonvertical.right.x
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if y >= bottom and y <= top and x >= left and x <= right
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return true
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false
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pointOnLine: (point, segment=true) ->
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if point.y is @y(point.x)
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if segment
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[littleY, bigY] = if @a.y < @b.y then [@a.y, @b.y] else [@b.y, @a.y]
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if littleY <= point.y and bigY >= point.y
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return true
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else
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return true
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false
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distanceSquaredToPoint: (point) ->
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# http://stackoverflow.com/a/1501725/540620
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return @a.distanceSquared point if @a.equals @b
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res = Math.min point.distanceSquared(@a), point.distanceSquared(@b)
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lineMagnitudeSquared = @a.distanceSquared @b
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t = ((point.x - @a.x) * (@b.x - @a.x) + (point.y - @a.y) * (@b.y - @a.y)) / lineMagnitudeSquared
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return @a.distanceSquared point if t < 0
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return @b.distanceSquared point if t > 1
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point.distanceSquared x: @a.x + t * (@b.x - @a.x), y: @a.y + t * (@b.y - @a.y)
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distanceToPoint: (point) ->
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Math.sqrt @distanceSquaredToPoint point
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toString: ->
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"lineSegment(a=#{@a}, b=#{@b}, slope=#{@slope}, y0=#{@y0}, left=#{@left}, right=#{@right}, bottom=#{@bottom}, top=#{@top})"
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serialize: ->
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{CN: @constructor.className, a: @a, b: @b}
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@deserialize: (o, world, classMap) ->
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new LineSegment o.a, o.b
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serializeForAether: -> @serialize()
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@deserializeFromAether: (o) -> @deserialize o
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module.exports = LineSegment
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