Merge pull request #406 from yungyuc/refactor/naca4-airfoil

Refactor the code related to NACA4 airfoil

modmesh/gui/naca.py

@@ -29,125 +29,24 @@
 Show NACA airfoil shape
 """
 
-import numpy as np
-
 from modmesh import core
 from modmesh import view
-
-
-def calc_naca4_points(number, npoint, open_trailing_edge=False,
-                      cosine_spacing=False):
-    """
-    Returns points in [0 1] for the given 4 digit NACA number string.
-    Reference from
-    https://ntrs.nasa.gov/api/citations/19930091108/downloads/19930091108.pdf
-    and https://github.com/dgorissen/naca
-    """
-
-    camber = float(number[0]) / 100.0
-    pos = float(number[1]) / 10.0
-    thick = float(number[2:]) / 100.0
-
-    a0 = +0.2969
-    a1 = -0.1260
-    a2 = -0.3516
-    a3 = +0.2843
-    a4 = -0.1015 if open_trailing_edge else -0.1036
-
-    if cosine_spacing:
-        xc = 0.5 * (1.0 - np.cos(np.linspace(0.0, np.pi, npoint + 1)))
-    else:
-        xc = np.linspace(0.0, 1.0, npoint + 1)
-
-    xh = np.sqrt(xc)
-    x2 = np.power(xc, 2)
-    x3 = np.power(xc, 3)
-    x4 = np.power(xc, 4)
-    yt = 5.0 * thick * (a0 * xh + a1 * xc + a2 * x2 + a3 * x3 + a4 * x4)
-
-    if pos == 0:
-        xu = xc
-        yu = yt
-        xl = xc
-        yl = -yt
-    else:
-        xc1 = xc[xc <= pos]
-        yc1 = camber / np.power(pos, 2) * xc1 * (2 * pos - xc1)
-        dyc1_dx = camber / np.power(pos, 2) * (2 * pos - 2 * xc1)
-
-        xc2 = xc[xc > pos]
-        yc2 = camber / np.power(1 - pos, 2) * (1 - 2 * pos + xc2) * (1 - xc2)
-        dyc2_dx = camber / np.power(1 - pos, 2) * (2 * pos - 2 * xc2)
-
-        yc = np.concatenate([yc1, yc2])
-        dyc_dx = np.concatenate([dyc1_dx, dyc2_dx])
-        theta = np.arctan(dyc_dx)
-
-        xu = xc - yt * np.sin(theta)
-        yu = yc + yt * np.cos(theta)
-        xl = xc + yt * np.sin(theta)
-        yl = yc - yt * np.cos(theta)
-
-    xr = np.concatenate([xu[::-1], xl[1:]])
-    yr = np.concatenate([yu[::-1], yl[1:]])
-    ret = np.vstack([xr, yr]).T.copy()
-    return ret
-
-
-def calc_sample_points(points):
-    # determine the number of sample points for a cubic bezier curve
-    spacing = 0.01
-    segments = np.hypot((points[:-1, 0] - points[1:, 0]),
-                        (points[:-1, 1] - points[1:, 1])) // spacing
-    nsample = np.where(segments > 2, segments - 1, 2).astype(int)
-    return nsample
-
-
-def linear_approximate(world, points):
-    for it in range(points.shape[0] - 1):
-        world.add_edge(points[it, 0], points[it, 1], 0,
-                       points[it + 1, 0], points[it + 1, 1], 0)
-    return
-
-
-def cubic_bezier_approximate(world, points, nsample=None):
-    Vector = core.Vector3dFp64
-
-    if nsample is None:
-        nsample = calc_sample_points(points)
-    for it in range(points.shape[0] - 1):
-        p1 = points[it] + (1 / 3) * (points[it + 1] - points[it])
-        p2 = points[it] + (2 / 3) * (points[it + 1] - points[it])
-
-        b = world.add_bezier([Vector(points[it, 0], points[it, 1], 0),
-                              Vector(p1[0], p1[1], 0),
-                              Vector(p2[0], p2[1], 0),
-                              Vector(points[it + 1, 0], points[it + 1, 1], 0)])
-        b.sample(nsample[it])
-    return
-
-
-def draw_naca4(world, number, npoint, fac, off_x, off_y,
-               use_bezier=False, **kw):
-    crds = calc_naca4_points(number=number, npoint=npoint, **kw)
-    crds *= fac  # scaling factor
-    crds[:, 0] += off_x  # offset in x
-    crds[:, 1] += off_y  # offset in y
-
-    if use_bezier:
-        cubic_bezier_approximate(world, crds)
-    else:
-        linear_approximate(world, crds)
-    return crds
+from modmesh.pilot import airfoil
 
 
 def runmain():
     """
     A simple example for drawing a couple of cubic Bezier curves.
     """
     w = core.WorldFp64()
-    draw_naca4(w, number='0012', npoint=101, fac=5.0, off_x=0.0, off_y=2.0,
-               open_trailing_edge=False, use_bezier=True, cosine_spacing=True)
+    naca4 = airfoil.Naca4(number='0012', open_trailing_edge=False,
+                          cosine_spacing=False)
+    sampler = airfoil.Naca4Sampler(w, naca4)
+    sampler.populate_points(npoint=101, fac=5.0, off_x=0.0, off_y=2.0)
+    if False:
+        sampler.draw_line()
+    else:
+        sampler.draw_cbc()
     wid = view.mgr.add3DWidget()
     wid.updateWorld(w)
     wid.showMark()

modmesh/pilot/__init__.py

@@ -0,0 +1,38 @@
+# Copyright (c) 2024, Yung-Yu Chen <[email protected]>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# - Redistributions of source code must retain the above copyright notice, this
+#   list of conditions and the following disclaimer.
+# - Redistributions in binary form must reproduce the above copyright notice,
+#   this list of conditions and the following disclaimer in the documentation
+#   and/or other materials provided with the distribution.
+# - Neither the name of the copyright holder nor the names of its contributors
+#   may be used to endorse or promote products derived from this software
+#   without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+
+"""
+Drawing and visualization sub-system of modmesh.
+"""
+
+from . import airfoil  # noqa: F401
+
+__all__ = [
+    'airfoil',
+]
+
+# vim: set ff=unix fenc=utf8 et sw=4 ts=4 sts=4: