From 35ff437164212441209e18d2f56903e591f2ef61 Mon Sep 17 00:00:00 2001
From: Tavmjong Bah <tavmjong@free.fr>
Date: Fri, 22 Jun 2007 11:11:19 +0000
Subject: Added polar coordinates. Added "Use" tab to dialog.

(bzr r3085)
---
 share/extensions/funcplot.py | 91 ++++++++++++++++++++++++++++++++++----------
 1 file changed, 70 insertions(+), 21 deletions(-)

(limited to 'share/extensions/funcplot.py')

diff --git a/share/extensions/funcplot.py b/share/extensions/funcplot.py
index e478a4b30..482df634a 100644
--- a/share/extensions/funcplot.py
+++ b/share/extensions/funcplot.py
@@ -1,5 +1,6 @@
 #!/usr/bin/env python 
 '''
+Copyright (C) 2007 Tavmjong Bah, tavmjong@free.fr
 Copyright (C) 2006 Georg Wiora, xorx@quarkbox.de
 Copyright (C) 2006 Johan Engelen, johan@shouraizou.nl
 Copyright (C) 2005 Aaron Spike, aaron@ekips.org
@@ -21,6 +22,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 Changes:
  * This program is a modified version of wavy.py by Aaron Spike.
  * 22-Dec-2006: Wiora : Added axis and isotropic scaling
+ * 21-Jun-2007: Tavmjong: Added polar coordinates
 
 '''
 import inkex, simplepath, simplestyle
@@ -28,8 +30,8 @@ from math import *
 from random import *
 
 def drawfunction(xstart, xend, ybottom, ytop, samples, width, height, left, bottom, 
-    fx = "sin(x)", fpx = "cos(x)", fponum = True, times2pi = False, isoscale = True, drawaxis = True):
-    
+    fx = "sin(x)", fpx = "cos(x)", fponum = True, times2pi = False, polar = False, isoscale = True, drawaxis = True):
+
     if times2pi == True:
         xstart = 2 * pi * xstart
         xend   = 2 * pi * xend   
@@ -38,12 +40,18 @@ def drawfunction(xstart, xend, ybottom, ytop, samples, width, height, left, bott
     scalex = width / (xend - xstart)
     xoff = left
     coordx = lambda x: (x - xstart) * scalex + xoff  #convert x-value to coordinate
+    if polar :  # Set scale so that left side of rectangle is -1, right side is +1.
+                # (We can't use xscale for both range and scale.)
+        centerx = left + width/2.0
+        polar_scalex = width/2.0
+        coordx = lambda x: x * polar_scalex + centerx  #convert x-value to coordinate
+
     scaley = height / (ytop - ybottom)
     yoff = bottom
     coordy = lambda y: (ybottom - y) * scaley + yoff  #convert y-value to coordinate
-    
+
     # Check for isotropic scaling and use smaller of the two scales, correct ranges
-    if isoscale:
+    if isoscale and not polar:
       if scaley<scalex:
         # compute zero location
         xzero = coordx(0)
@@ -70,6 +78,7 @@ def drawfunction(xstart, xend, ybottom, ytop, samples, width, height, left, bott
     # step is the distance between nodes on x
     step = (xend - xstart) / (samples-1)
     third = step / 3.0
+    ds = step * 0.001 # Step used in calculating derivatives
 
     a = [] # path array 
     # add axis
@@ -87,29 +96,60 @@ def drawfunction(xstart, xend, ybottom, ytop, samples, width, height, left, bott
 
     # initialize function and derivative for 0;
     # they are carried over from one iteration to the next, to avoid extra function calculations. 
-    y0 = f(xstart) 
-    if fponum == True: # numerical derivative, using 0.001*step as the small differential
-        d0 = (f(xstart + 0.001*step) - y0)/(0.001*step)
+    x0 =   xstart
+    y0 = f(xstart)
+    if polar :
+      xp0 = y0 * cos( x0 )
+      yp0 = y0 * sin( x0 )
+      x0 = xp0
+      y0 = yp0
+    if fponum or polar: # numerical derivative, using 0.001*step as the small differential
+        x1 = xstart + ds # Second point AFTER first point (Good for first point)
+        y1 = f(x1)
+        if polar :
+            xp1 = y1 * cos( x1 )
+            yp1 = y1 * sin( x1 )
+            x1 = xp1
+            y1 = yp1
+        dx0 = (x1 - x0)/ds 
+        dy0 = (y1 - y0)/ds
     else: # derivative given by the user
-        d0 = fp(xstart)
+        dx0 = 0 # Only works for rectangular coordinates
+        dy0 = fp(xstart)
 
     # Start curve
-    a.append([' M ',[coordx(xstart), coordy(y0)]]) # initial moveto
+    a.append([' M ',[coordx(x0), coordy(y0)]]) # initial moveto
 
     for i in range(int(samples-1)):
-        x = (i+1) * step + xstart
-        y1 = f(x)
-        if fponum == True: # numerical derivative
-            d1 = (y1 - f(x - 0.001*step))/(0.001*step)
+        x1 = (i+1) * step + xstart
+        x2 = x1 - ds # Second point BEFORE first point (Good for last point)
+        y1 = f(x1)
+        y2 = f(x2)
+        if polar :
+            xp1 = y1 * cos( x1 )
+            yp1 = y1 * sin( x1 )
+            xp2 = y2 * cos( x2 )
+            yp2 = y2 * sin( x2 )
+            x1 = xp1
+            y1 = yp1
+            x2 = xp2
+            y2 = yp2
+        if fponum or polar: # numerical derivative
+            dx1 = (x1 - x2)/ds
+            dy1 = (y1 - y2)/ds
         else: # derivative given by the user
-            d1 = fp(x)
+            dx1 = 0 # Only works for rectangular coordinates
+            dy1 = fp(x1)
         # create curve
-        a.append([' C ',[coordx(x - step + third), coordy(y0 + (d0 * third)), 
-            coordx(x - third), coordy(y1 - (d1 * third)),
-            coordx(x), coordy(y1)]])
-        y0 = y1 # next segment's y0 is this segment's y1
-        d0 = d1 # we assume the function is smooth everywhere, so carry over the derivative too
-            
+        a.append([' C ',
+                  [coordx(x0 + (dx0 * third)), coordy(y0 + (dy0 * third)), 
+                   coordx(x1 - (dx1 * third)), coordy(y1 - (dy1 * third)),
+                   coordx(x1),                 coordy(y1)]
+                  ])
+        x0  = x1  # Next segment's start is this segments end
+        y0  = y1
+        dx0 = dx1 # Assume the function is smooth everywhere, so carry over the derivative too
+        dy0 = dy1    
     return a
 
 class FuncPlot(inkex.Effect):
@@ -127,6 +167,10 @@ class FuncPlot(inkex.Effect):
                         action="store", type="inkbool", 
                         dest="times2pi", default=True,
                         help="Multiply x-range by 2*pi")    
+        self.OptionParser.add_option("--polar",
+                        action="store", type="inkbool", 
+                        dest="polar", default=False,
+                        help="Plot using polar coordinates")    
         self.OptionParser.add_option("--ybottom",
                         action="store", type="float", 
                         dest="ybottom", default=-1.0,
@@ -167,6 +211,10 @@ class FuncPlot(inkex.Effect):
                         action="store", type="string", 
                         dest="tab", default="sampling",
                         help="The selected UI-tab when OK was pressed") 
+        self.OptionParser.add_option("--funcplotuse",
+                        action="store", type="string", 
+                        dest="funcplotuse", default="",
+                        help="dummy") 
         self.OptionParser.add_option("--pythonfunctions",
                         action="store", type="string", 
                         dest="pythonfunctions", default="",
@@ -191,7 +239,7 @@ class FuncPlot(inkex.Effect):
                 if t:
                     newpath.set('transform', t)
                     
-                # top and bottom where exchanhged
+                # top and bottom were exchanged
                 newpath.set('d', simplepath.formatPath(
                             drawfunction(self.options.xstart,
                                 self.options.xend,
@@ -203,6 +251,7 @@ class FuncPlot(inkex.Effect):
                                 self.options.fpofx,
                                 self.options.fponum,
                                 self.options.times2pi,
+                                self.options.polar,
                                 self.options.isoscale,
                                 self.options.drawaxis)))
                 newpath.set('title', self.options.fofx)
-- 
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