1 files changed, 42 insertions, 0 deletions
diff --git a/src/toys/py2geom_glue.py b/src/toys/py2geom_glue.py
new file mode 100644
index 0000000..fa2b5ae
--- /dev/null
+++ b/src/toys/py2geom_glue.py
@@ -0,0 +1,42 @@
+#!/usr/bin/python
+
+def choose(n, k):
+    r = 1
+    for i in range(1, k+1):
+        r = (r*(n-k+i))/i
+    return r
+
+def W(n, j, k):
+    q = (n+1)/2.
+    if((n & 1) == 0 and j == q and k == q):
+        return 1
+    if(k > n-k):
+        return W(n, n-j, n-k)
+    assert((k <= q))
+    if(k >= q):
+        return 0
+    # assert(!(j >= n-k));
+    if(j >= n-k):
+        return 0
+    # assert(!(j < k));
+    if(j < k):
+        return 0
+    return float(choose(n-2*k-1, j-k)) / choose(n,j);
+
+# this produces a degree 2q bezier from a degree k sbasis
+def sbasis_to_bezier(B, q):
+    if(q == 0):
+        q = len(B)
+    n = q*2
+    result = [0.0 for i in range(n)]
+    if(q > len(B)):
+        q = len(B)
+    n -= 1
+    for k in range(q):
+        for j in range(n-k+1):
+            result[j] += (W(n, j, k)*B[k][0] +
+                          W(n, n-j, k)*B[k][1])
+    return result
+
+def lerp(a, b, t):
+    return (1-t)*a + t*b