Question

我的最终目标如下：

我有一个巨大的点数据集，表示一个部件将如何逐层3D打印。我需要通过这些点创建一条直线并沿着这条直线挤出一个圆（所以重建部件，因为它将在以后打印）。

我最初尝试做一个样条曲线，但是这会尝试创建一条平滑线并且根本不遵循这些点。我尝试更改minDeg和maxDeg选项，但这仍然没有足够的帮助来创建我需要的实际曲线。

See this result for the spline

See here the actual path (the above spline is one of the infill parts)

所以我一次尝试在两个点之间创建一个样条线，然后在创建一条线时将它们全部加在一起。这看起来很有希望，因为现在我确实得到了实际的尖角和线条通过精确点。但是，现在当我尝试沿着它挤出时，挤出型材的法线不会随着钢丝的角度而变化。

This is what happens with the last thing I tried

我在这个问题上度过了最后4天，尝试了许多论坛和问题，但在pythonocc（opencascade）的世界中感到完全迷失了。

我的代码如下：

from __future__ import print_function

from OCC.gp import gp_Pnt, gp_Ax2, gp_Dir, gp_Circ
from OCC.GeomAPI import GeomAPI_PointsToBSpline
from OCC.TColgp import TColgp_Array1OfPnt
from OCC.BRepBuilderAPI import BRepBuilderAPI_MakeEdge,         
BRepBuilderAPI_MakeWire, BRepBuilderAPI_MakeFace
from OCC.BRepOffsetAPI import BRepOffsetAPI_MakePipe

from OCC.Display.SimpleGui import init_display
display, start_display, add_menu, add_function_to_menu = init_display()

def pipe():
# the bspline path, must be a wire
# This will later be in a for loop but this is merely to validate the method         
using three different points.

array = TColgp_Array1OfPnt(1,2)
makeWire = BRepBuilderAPI_MakeWire()

point1 = gp_Pnt(0,0,0)
point2 = gp_Pnt(0,0,1)
array.SetValue(1, point1)
array.SetValue(2, point2)
spline = GeomAPI_PointsToBSpline(array).Curve()
edge = BRepBuilderAPI_MakeEdge(spline).Edge()

makeWire.Add(edge)

point1 = gp_Pnt(0, 0, 1)
point2 = gp_Pnt(0, 1, 2)
array.SetValue(1, point1)
array.SetValue(2, point2)
spline = GeomAPI_PointsToBSpline(array).Curve()
edge = BRepBuilderAPI_MakeEdge(spline).Edge()

makeWire.Add(edge)

point1 = gp_Pnt(0, 1, 2)
point2 = gp_Pnt(0, 2, 2)
array.SetValue(1, point1)
array.SetValue(2, point2)
spline = GeomAPI_PointsToBSpline(array).Curve()
edge = BRepBuilderAPI_MakeEdge(spline).Edge()

makeWire.Add(edge)

makeWire.Build()
wire = makeWire.Wire()

# the bspline profile. Profile mist be a wire/face
point = gp_Pnt(0,0,0)
dir = gp_Dir(0,0,1)
circle = gp_Circ(gp_Ax2(point,dir), 0.2)
profile_edge = BRepBuilderAPI_MakeEdge(circle).Edge()
profile_wire = BRepBuilderAPI_MakeWire(profile_edge).Wire()
profile_face = BRepBuilderAPI_MakeFace(profile_wire).Face()

# pipe
pipe = BRepOffsetAPI_MakePipe(wire, profile_face).Shape()

display.DisplayShape(profile_edge, update=False)
display.DisplayShape(wire, update=True)
display.DisplayShape(pipe, update=True)

if __name__ == '__main__':
pipe()
start_display()

Answer 1

虽然导线的边缘连接，但它们不能平滑过渡。 BrepOffsetAPI_MakePipe：

通过沿着电线Spine扫描形状轮廓来构造管道。脊柱与轮廓形成的角度沿着管道的长度保持。警告脊柱必须连续G1;也就是说，在导线的两个边缘的连接顶点上，左侧和右侧的切向量必须具有相同的方向，但不一定是相同的大小。

可以找到另一个连续性描述here，我们需要相切（G1）。如果两条相邻曲线的末端不相切，则扫描将无法保持相同的角度（脊柱与轮廓相同）。

最简单的解决方案是切割管道。

def pipe(point1, point2):
    makeWire = BRepBuilderAPI_MakeWire()
    edge = BRepBuilderAPI_MakeEdge(point1, point2).Edge()
    makeWire.Add(edge)
    makeWire.Build()
    wire = makeWire.Wire()

    dir = gp_Dir(point2.X() - point1.X(), point2.Y() - point1.Y(), point2.Z() - point1.Z())
    circle = gp_Circ(gp_Ax2(point1,dir), 0.2)
    profile_edge = BRepBuilderAPI_MakeEdge(circle).Edge()
    profile_wire = BRepBuilderAPI_MakeWire(profile_edge).Wire()
    profile_face = BRepBuilderAPI_MakeFace(profile_wire).Face()
    pipe = BRepOffsetAPI_MakePipe(wire, profile_face).Shape()
    display.DisplayShape(pipe, update=True)

if __name__ == '__main__':
    pipe(gp_Pnt(0,0,0), gp_Pnt(0,0,1))
    pipe(gp_Pnt(0,0,1), gp_Pnt(0,1,2))     
    pipe(gp_Pnt(0,1,2), gp_Pnt(0,2,2))
    start_display()

我们可以添加球体来填补空白。

from OCC.BRepPrimAPI import BRepPrimAPI_MakeSphere

def sphere(centre, radius):
    sphere = BRepPrimAPI_MakeSphere (centre, radius).Shape()
    display.DisplayShape(sphere, update=True)

def pipe(point1, point2):
    ...

if __name__ == '__main__':
    pipe(gp_Pnt(0,0,0), gp_Pnt(0,0,1))
    sphere(gp_Pnt(0,0,1), 0.2)
    pipe(gp_Pnt(0,0,1), gp_Pnt(0,1,2))     
    sphere(gp_Pnt(0,1,2), 0.2)
    pipe(gp_Pnt(0,1,2), gp_Pnt(0,2,2))
    start_display()

或者，您可以实现圆角算法，例如ChFi2d Class提供的算法。鉴于激光打印环境和算法的平面特征，我将点映射到xy平面。

from OCC.ChFi2d import ChFi2d_AnaFilletAlgo

def filletEdges(ed1, ed2):
    radius = 0.3
    f = ChFi2d_AnaFilletAlgo()
    f.Init(ed1,ed2,gp_Pln())
    f.Perform(radius)
    return f.Result(ed1, ed2)

def pipe():
    # the points
    p1 = gp_Pnt(0,0,0)
    p2 = gp_Pnt(0,1,0)
    p3 = gp_Pnt(1,2,0)
    p4 = gp_Pnt(2,2,0)
    # the edges
    ed1 = BRepBuilderAPI_MakeEdge(p1,p2).Edge()
    ed2 = BRepBuilderAPI_MakeEdge(p2,p3).Edge()
    ed3 = BRepBuilderAPI_MakeEdge(p3,p4).Edge()
    # inbetween
    fillet12 = filletEdges(ed1, ed2)
    fillet23 = filletEdges(ed2, ed3) 
    # the wire
    makeWire = BRepBuilderAPI_MakeWire()
    makeWire.Add(ed1)
    makeWire.Add(fillet12)
    makeWire.Add(ed2)
    makeWire.Add(fillet23)
    makeWire.Add(ed3)
    makeWire.Build()
    wire = makeWire.Wire()
    # the pipe
    dir = gp_Dir(0,1,0)
    circle = gp_Circ(gp_Ax2(p1,dir), 0.2)
    profile_edge = BRepBuilderAPI_MakeEdge(circle).Edge()
    profile_wire = BRepBuilderAPI_MakeWire(profile_edge).Wire()
    profile_face = BRepBuilderAPI_MakeFace(profile_wire).Face()
    pipe = BRepOffsetAPI_MakePipe(wire, profile_face).Shape()
    display.DisplayShape(pipe, update=True)

if __name__ == '__main__':
    pipe()
    start_display()

Pythonocc / Opencascade |通过点直线创建管道，轮廓不会改变正常

1 个答案: