Successfully made a twisty-torus

examples.py

@@ -126,40 +126,107 @@ def twist_nonlinear(dx0 = 2, dz=0.2, count=3, scale=0.99, layers=100):
         mesh = mesh.concat(meshutil.close_boundary_simple(b_sub1[::-1,:]))
     return mesh
 
-# Wrap some boundary around a (sorta) torus that is along XY.
+# Generate a frame with 'count' boundaries in the XZ plane.
+# Each one rotates by 'ang' as it moves by 'dz'.
+# dx0 is center-point distance from each to the origin.
+def gen_twisted_boundary(count=4, dx0=2, dz=0.2, ang=0.1):
+    b = numpy.array([
+        [0, 0, 0],
+        [1, 0, 0],
+        [1, 0, 1],
+        [0, 0, 1],
+    ], dtype=numpy.float64) - [0.5, 0, 0.5]
+    # Generate 'seed' transformations:
+    xfs = [meshutil.Transform().translate(dx0, 0, 0).rotate([0,1,0], numpy.pi * 2 * i / count)
+           for i in range(count)]
+    # (we'll increment the transforms in xfs as we go)
+    while True:
+        xfs_new = []
+        bs = []
+        for i, xf in enumerate(xfs):
+            # Generate a boundary from running transform:
+            b_i = xf.apply_to(b)
+            bs.append(b_i)
+            # Increment transform i:
+            xf2 = xf.rotate([0,1,0], ang)
+            xfs_new.append(xf2)
+        xfs = xfs_new
+        yield bs
+
+# This is to see how well it works to compose generators:
+def gen_inc_y(gen, dy=0.1):
+    xf = meshutil.Transform()
+    for bs in gen:
+        bs2 = [xf.apply_to(b) for b in bs]
+        yield bs2
+        xf = xf.translate(0, dy, 0)
+
+# Wrap a boundary generator around a (sorta) torus that is along XY.
 # producing a mesh.
-# 'frames' sets resolution, 'dx0' sets radius.
-# 'b' can be None, and then a 1x1 boundary in XZ is used,
-# centered at (0,0,0).  If one is supplied, it should also
-# be oriented roughly along XZ.
-def torus_xy(bs=None, dx0=2, frames=100):
-    if b is None:
-        b = numpy.array([
-            [0, 0, 0],
-            [1, 0, 0],
-            [1, 0, 1],
-            [0, 0, 1],
-        ], dtype=numpy.float64) - [0.5, 0, 0.5]
-    ang = -numpy.pi*2 / frames
-    # negative because of winding order annoyance
+# 'frames' sets resolution, 'rad' sets radius (the boundary's origin
+# sweeps through this radius - it's not 'inner' or 'outer' radius).
+#
+# generator should produce lists of boundaries which are oriented
+# roughly in XZ.  This will get 'frames' elements from it if
+# possible.
+def gen_torus_xy(gen, rad=2, frames=100):
+    ang = numpy.pi*2 / frames
+    xf = meshutil.Transform().translate(rad, 0, 0)
+    for i,bs in enumerate(gen):
+        if i >= frames:
+            break
+        bs2 = [xf.apply_to(b) for b in bs]
+        yield bs2
+        xf = xf.rotate([0,0,1], ang)
+
+# String together boundaries from a generator.
+# If count is nonzero, run only this many iterations.
+def gen2mesh(gen, count=0, flip_order=False, loop=False):
+    # Get first list of boundaries:
+    bs_first = next(gen)
+    bs_last = bs_first
+    # TODO: Begin and end with close_boundary_simple
     mesh = meshutil.FaceVertexMesh.Empty()
-    xf = meshutil.Transform() \
-        .translate(dx0, 0, 0)
-    b0 = xf.apply_to(b)
-    for layer in range(frames):
-        b_sub0 = xf.apply_to(b)
-        incr = meshutil.Transform().rotate([0,0,1], ang)
-        b_sub1 = xf.compose(incr).apply_to(b)
-        m = meshutil.join_boundary_simple(b_sub0, b_sub1)
-        mesh = mesh.concat(m)
-        xf = xf.compose(incr)
+    for i,bs_cur in enumerate(gen):
+        if count > 0 and i >= count:
+            break
+        for j,b in enumerate(bs_cur):
+            if flip_order:
+                m = meshutil.join_boundary_simple(b, bs_last[j])
+            else:
+                m = meshutil.join_boundary_simple(bs_last[j], b)
+            mesh = mesh.concat(m)
+        bs_last = bs_cur
+    if loop:
+        for b0,b1 in zip(bs_last, bs_first):
+            if flip_order:
+                m = meshutil.join_boundary_simple(b1, b0)
+            else:
+                m = meshutil.join_boundary_simple(b0, b1)
+            mesh = mesh.concat(m)
     return mesh
 
+def twist_from_gen():
+    gen = gen_inc_y(gen_twisted_boundary())
+    mesh = gen2mesh(gen, 100, True)
+    return mesh
+
+# frames = How many step to build this from:
+# turn = How many full turns to make in inner twist
+# count = How many inner twists to have
+def twisty_torus(frames = 200, turns = 4, count = 4, rad = 4):
+    # In order to make this line up properly:
+    angle = numpy.pi * 2 * turns / frames
+    gen = gen_torus_xy(gen_twisted_boundary(count=count, ang=angle), rad=rad, frames=frames)
+    return gen2mesh(gen, 0, flip_order=True, loop=True)
+
 def main():
     fns = {
         ram_horn: "ramhorn.stl",
         twist: "twist.stl",
         twist_nonlinear: "twist_nonlinear.stl",
+        twist_from_gen: "twist_from_gen.stl",
+        twisty_torus: "twisty_torus.stl",
     }
     for f in fns:
         fname = fns[f]