sketch

Author: bottler

readSketchnet.py

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+#This file contains just enough logic to get data from the
+#sketchnet svg files as points-on-paths
+
+#info
+#http://www.johndcook.com/blog/2009/12/21/bezier-basics/
+#https://www.w3.org/TR/SVG/paths.html
+
+#USAGE:
+## If filename is one of the SVG files from sketchnet and you run
+#   data = readSketchnet.read(filename)
+##then data2 will be a list of numpy arrays giving strokes
+##of the character.
+
+import xml.etree.ElementTree as ET
+import numpy as np
+import re
+
+ns = {"i":"http://www.w3.org/2000/svg"}
+
+#parses a file to produce a big list of all the path data
+def fileToData(filename):
+    num=r"(\d+(\.\d+)?)"
+    straight="M{0} {0} L{0} {0} ".format(num)
+    curve = "M{0} {0} (C{0} {0} {0} {0} {0} {0} )+".format(num)
+    curvepiece = "C{0} {0} {0} {0} {0} {0} ".format(num)
+
+    r = ET.parse(filename)
+    g = r.find("i:g",ns).find("i:g",ns)
+    svgTexts=[p.attrib["d"] for p in g.findall("i:path",ns)]
+
+    out = []
+    for text in svgTexts:
+        m=re.match(straight, text)
+        if m:
+            g = m.groups()
+            points = ((float(g[0]),float(g[2])),(float(g[4]),float(g[6])))
+            out.append(points)
+        else:
+            m=re.match(curve, text)
+            if(m):
+                g = m.groups()
+                startpt = (float(g[0]),float(g[2]))
+                curvedata = []
+                for p in re.finditer(curvepiece, text):
+                    g= p.groups()
+                    vals = ((float(g[0]),float(g[2])),
+                            (float(g[4]),float(g[6])),
+                            (float(g[8]),float(g[10])))
+                    curvedata.append(vals)
+                #print (text,"\n", startpt,curvedata)
+                out.append(("C",startpt,curvedata)) #C just for convenience
+            else:
+                raise RuntimeError("Unexpected path string: "+text)
+    return out
+
+
+def prepareCoeffs():
+    t=np.arange(0.1,1,0.1)
+    ot = 1-t
+    out = np.vstack([ot*ot*ot,3*ot*ot*t,3*ot*t*t,t*t*t])
+    return out.T
+coeffs = prepareCoeffs() #9x4
+
+#takes the data from a file and returns a list of strokes,
+#each one being an Nx2 numpy array.
+#This means expanding the bezier curves
+def dataToStrokePoints(data):
+    out = []
+    for stroke in data:
+        if len(stroke)==2: #straight line
+            x = np.array(stroke)
+        else:
+            x=[stroke[1]]
+            for i in stroke[2]:
+                if False: # show all control points
+                    for pt in range(3):
+                        x.append(i[pt])
+                else:
+                    controlPts=np.vstack([x[-1],i[0],i[1],i[2]]) # 4x2
+                    x.append(np.dot(coeffs,controlPts)) #9x2
+                    x.append(i[2])
+        out.append(np.vstack(x))
+    return out
+
+def read(filename):
+    return dataToStrokePoints(fileToData(filename))