Arrows in drawn by the arrow3d are not clipped sometimes #68

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1. bdeket commented on Sep 1, 2020

   

   bdeket

   on Sep 1, 2020

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   This is not so much a new error, but an error that already existed in the put-arrow function. The arrows were never clipped.
   For vector-fields3d this was not a problem since the base-point of the vector was always lying within the plot area.
   The arrow3d just expose this problem since the start of an arrow can now be outside the area.

   For the 2D case there is a similar clipping error when zooming in very deep.

   (plot
    (list (arrows '((0 .5)(2 .5))
                  #:arrow-head-size-or-scale '(= 50))
          (arrows '((0 -.5)(2 -.5))))
    #:x-min (- 2 1e-11) #:y-min -1
    #:x-max (+ 2 1e-11) #:y-max +1)
   

   

   vector-field has the same error:

   (plot
    (vector-field (λ (x y) (if (and (< (- 2 1e-11) x (+ 2 1e-11))
                                    (< -.1 y .1))
                               (list -2 0)
                               (list 0 0)))
                  #:samples 3
                  #:scale 1)
    #:x-min (- 2 1e-11) #:y-min -1
    #:x-max (+ 2 1e-11) #:y-max +1)
   

   

   (** in both plots, the lines should be going to the left)

   For the 2D case, this is happening when one end of the vector is a large (rational?) negative number. For Lines etc. this is solved by clipping the lines that go outside the drawing area.
   For arrows, I was hesitant to start clipping, since that also will affect the arrowheads.