DMJ_FollowCurve

Distort to follow an arbitrary curve. (BETA, SUBJECT TO CHANGE) You can use this transform to make a fractal shape follow a curve that you define.
 class DMJ_FollowCurve(common.ulb:UserTransform) {
   ; Distort to follow an arbitrary curve. (BETA, SUBJECT TO CHANGE)
   ; You can use this transform to make a fractal shape follow a
   ; curve that you define.
   
 public:
   import "common.ulb"
 ;  $define debug
   
   func DMJ_FollowCurve(Generic pparent)
     UserTransform.UserTransform(pparent)
 
     m_PolyCurve = new DMJ_PolyCurve()
     m_Selector = new @f_selector(pparent)
     m_Selector.SetCurve(m_PolyCurve)
     m_PolyCurve.SetExtensionMode(@p_endpoints)
     m_PolyCurve.Rasterize(1)      ; note that we enable arc lengths (makes Rasterize() slower)
 
     m_Handles = new @f_handles(pparent)  ; create handle object
     m_Selector.SetHandles(m_Handles)  ; note we're not allowing screen-relative here
   endfunc
   
   func Init(complex pz)
     UserTransform.Init(pz)
     m_Handles.Init(pz)
   endfunc
   
   complex func Iterate(complex pz)
     complex point
     float segment = 0
     float segmentoffset = 0
     float distancesquared = 0
     float isleft = 0.0
     complex oz = pz
 
     ; the assignment here seems to be required
     point = \
     m_PolyCurve.ClosestPoint(pz, segment, segmentoffset, distancesquared)
     isleft = m_PolyCurve.IsLeft(pz, floor(segment))
     pz = m_PolyCurve.DistanceAlongCurve(segment, true)  ; should be a parameter here instead of true
     pz = pz + segmentoffset                ; if we have a linear offset (extended segment), include it
     if (isleft > 0)
       isleft = 1
     elseif (isleft < 0)
       isleft = -1
     endif
     $ifdef debug
       int testx = 700
       int testy = 400
       if (#x == testx && #y == testy)
         print("FollowCurve.Iterate() trace")
         print("ClosestPoint: ", point)
         print("segment: ", segment)
         print("segmentoffset: ", segmentoffset)
         print("IsLeft: ", isleft)
         print("IsLeft1: ", m_PolyCurve.IsLeftLine(oz, (-1.5,0), (1.5,0)))
         print("IsLeft2: ", m_PolyCurve.IsLeftLine(oz, (1.5,0), (0,-1)))
         print("IsLeft3: ", m_PolyCurve.IsLeftLine(oz, (0,-1), (-1.5,0)))
         print("IsLeft4: ", m_PolyCurve.IsLeftQuadraticCore(oz, (-1.5,0), (0,-1), (1.5,0)))
         print("IsLeft5: ", m_PolyCurve.IsLeftLine((0,-1), (-1.5,0), (1.5,0)))
         print("DistanceAlongCurve: ", pz-segmentoffset)
       endif
     $endif
     pz = (real(pz)+real(@p_offset))*real(@p_scale) + flip(-sqrt(distancesquared)*isleft+imag(@p_offset))*imag(@p_scale)
     $ifdef debug
       if (#x == testx && #y == testy)
         print("final pz: ", pz)
       endif
     $endif
 
     m_Handles.Iterate(pz)
     m_Solid = m_Handles.IsSolid()
     point = point + 1        ; **** silences compiler warning
     
     return pz
   endfunc
   
 protected:
   DMJ_PolyCurve m_PolyCurve
   Handles m_Handles
   DMJ_PolyCurveSelector m_Selector
   
 default:
   title = "Follow Curve (BETA)"
   rating = notRecommended
   
   int param v_dmj_followcurve
     caption = "Version (DMJ_FollowCurve)"
     default = 100
     hint = "This version parameter is used to detect when a change has been made to the formula that is incompatible with the previous version. When that happens, this field will reflect the old version number to alert you to the fact that an alternate rendering is being used."
     visible = @v_dmj_followcurve < 100
   endparam
 
   complex param p_offset
     caption = "Origin"
     default = (0,0)
     hint = "Sets the origin for transformed pixels. This is the point that will be used at the starting point of the curve. The easiest way to set this is to disable the transform, then use the eyedropper."
   endparam
   complex param p_scale
     caption = "Scale"
     default = (1,1)
     hint = "Sets the scale of the transform around the shape (real) and out from the shape (imaginary)."
   endparam
   int param p_endpoints
     caption = "Endpoints"
     default = 1
     enum = "stop at ends" "extend lines"
     hint = "Sets how the transform will behave near unclosed curve endpoints. 'Stop at ends' will cause the transform to curve inward at the ends. 'Extend lines' will act as though the curve has been extended in infinite lines from the endpoints. This parameter has no effect if your curve is completely closed."
   endparam
   int param p_method
     caption = "Mapping Method"
     default = 0
     enum = "closest point" "closest curve"
     visible = false
     hint = "Sets the method the transform will use to warp the complex plane to follow your curve. 'Closest point' is fast and works reasonably well, but in tight corners or at large distances from the curve it may show unwanted bunching. 'Closest curve' is slower but handles tight corners better."
   endparam
   
   heading
     caption = "Handle Options"
     expanded = false
   endheading
   Handles param f_handles
     caption = "Handle Options"
     selectable = false
   endparam
 
   heading
     caption = "Curve Options"
     expanded = true
   endheading
   DMJ_PolyCurveSelector param f_selector
     caption = "Curve Definition"
     default = DMJ_SelectorArbitraryPolygon
     hint = "Sets the method by which you will define your curve or polygon."
   endparam
   
 }
Method Summary
`void`	`Init(complex pz)` Set up for a sequence of values
`complex`	`Iterate(complex pz)` Transform a single point within a sequence
Constructor Summary
`DMJ_FollowCurve()`
`DMJ_FollowCurve(Generic pparent)` $define debug
dmj5 Class DMJ_FollowCurve

DMJ_FollowCurve

DMJ_FollowCurve

Init

Iterate

dmj5
Class DMJ_FollowCurve
