PythonOCC基础使用：曲面建模

ゞ浴缸里的玫瑰 2022-01-23 11:47 1626阅读 0赞

opencascade 提供了基本曲面（平面，圆柱面，锥面，球面），以及Bezier()和B-样条曲面，回转曲面，拉伸和偏移曲面，曲面裁剪后可以得到裁剪曲面（trimmed surface）啊

*  贝塞尔曲线(Bézier curve)，又称贝兹曲线或贝济埃曲线，是应用于二维图形应用程序的数学曲线。一般的矢量图形软件通过它来精确画出曲线，贝兹曲线由线段与节点组成，节点是可拖动的支点，线段像可伸缩的皮筋，我们在绘图工具上看到的钢笔工具就是来做这种矢量曲线的。
 *  B-样条是贝兹曲线(又称贝塞尔曲线)的一种一般化，可以进一步推广为非均匀有理B样条（NURBS），使得我们能给更多一般的几何体建造精确的模型。

### 直纹曲面（ruled surface） ###

直纹曲面是两条曲线形成的曲面（通过直线沿着两条曲线上的点运动形成的），平面（平行直线），圆锥面（平行圆用直线连接）

*  **1.由两条曲线生成对应曲面**  
    ![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc1NTM4NA_size_16_color_FFFFFF_t_70]`geomfill_Surface` 该函数是核心函数

from OCC.Core.GeomFill import GeomFill_Pipe, geomfill_Surface
    from OCC.Core.gp import gp_Pnt
    from OCC.Core.BRepBuilderAPI import  BRepBuilderAPI_MakeEdge, BRepBuilderAPI_MakeWire
    from OCC.Core.TColgp import TColgp_HArray1OfPnt
    from OCC.Core.GeomAPI import GeomAPI_Interpolate
    
    
    
    # 生成第一个曲线
    Linearray1 = TColgp_HArray1OfPnt(1, 5)
    Linearray1.SetValue(1, gp_Pnt(5, 0, 0))
    Linearray1.SetValue(2, gp_Pnt(4, 1.5, 0))
    Linearray1.SetValue(3, gp_Pnt(3, 2, 0))
    Linearray1.SetValue(4, gp_Pnt(2, 3, 0))
    Linearray1.SetValue(5, gp_Pnt(0, 4.5, 0))
    bspline_11 = GeomAPI_Interpolate(Linearray1, False, 0.00001)
    bspline_11.Perform()
    bspline_21 = bspline_11.Curve()
    bspline_31 = BRepBuilderAPI_MakeEdge(bspline_21)
    bspline1 = BRepBuilderAPI_MakeWire(bspline_31.Edge()).Wire()
    
    # 生成第二个曲线
    Linearray2 = TColgp_HArray1OfPnt(1, 5)
    Linearray2.SetValue(1, gp_Pnt(8, 0, 5))
    Linearray2.SetValue(2, gp_Pnt(7, 1.7, 5))
    Linearray2.SetValue(3, gp_Pnt(6, 2.4, 5))
    Linearray2.SetValue(4, gp_Pnt(3, 3.2, 5))
    Linearray2.SetValue(5, gp_Pnt(1, 5, 5))
    bspline_12 = GeomAPI_Interpolate(Linearray2, False, 0.00001)
    bspline_12.Perform()
    bspline_22 = bspline_12.Curve()
    bspline_32 = BRepBuilderAPI_MakeEdge(bspline_22)
    bspline2 = BRepBuilderAPI_MakeWire(bspline_32.Edge()).Wire()
    
    # 二个曲线生成曲面
    surface=geomfill_Surface(bspline_21,bspline_22)
    
    
    if __name__ == "__main__":
        from OCC.Display.SimpleGui import init_display
        display, start_display, add_menu, add_function_to_menu = init_display()
        display.DisplayShape(bspline1, update=True)
        display.DisplayShape(bspline2, update=True)
        display.DisplayShape(surface, update=True)
    
    
        start_display()

`brepfill_Face()` 计算两edge的直纹曲面

参数:

Edge1 (TopoDS_Edge &) –
    Edge2 (TopoDS_Edge &) –

返回类型:

`TopoDS_Face`

`brepfill_Shell()`计算出两wire（环）的直纹曲面。两环必须要有相同数量的edges  
参数:

Wire1 (TopoDS_Wire &) –
    Wire2 (TopoDS_Wire &) –

返回类型:

`TopoDS_Shell`

*  **2.由相应的点生成曲面**

from OCC.Core.gp import gp_Pnt
    from OCC.Core.BRepBuilderAPI import BRepBuilderAPI_MakeFace
    from OCC.Core.TColgp import TColgp_Array2OfPnt
    from OCC.Core.GeomAPI import GeomAPI_PointsToBSplineSurface, GeomAPI_PointsToBSpline
    from OCC.Core.GeomAbs import GeomAbs_C2
    from OCC.Core.ShapeAnalysis import ShapeAnalysis_Surface, shapeanalysis_GetFaceUVBounds
    
    
    p1 = gp_Pnt(-15, 200, 10)
    p2 = gp_Pnt(5, 204, 0)
    p3 = gp_Pnt(15, 200, 0)
    p4 = gp_Pnt(-15, 20, 15)
    p5 = gp_Pnt(-5, 20, 0)
    p6 = gp_Pnt(15, 20, 35)
    
    array = TColgp_Array2OfPnt(1, 3, 1, 2)
    array.SetValue(1, 1, p1)
    array.SetValue(2, 1, p2)
    array.SetValue(3, 1, p3)
    array.SetValue(1, 2, p4)
    array.SetValue(2, 2, p5)
    array.SetValue(3, 2, p6)
    bspl_surf = GeomAPI_PointsToBSplineSurface(array, 3, 8, GeomAbs_C2,0.001).Surface()
    face = BRepBuilderAPI_MakeFace(bspl_surf, 1e-6).Face()
    # umin, umax, vmin, vmax = shapeanalysis_GetFaceUVBounds(face)
    # print(umin, umax, vmin, vmax)
    
    if __name__ == "__main__":
        from OCC.Display.SimpleGui import init_display
        display, start_display, add_menu, add_function_to_menu = init_display()
        display.DisplayShape(p1, update=True)
        display.DisplayShape(p2, update=True)
        display.DisplayShape(p3, update=True)
        display.DisplayShape(p4, update=True)
        display.DisplayShape(p5, update=True)
        display.DisplayShape(p6, update=True)
        display.DisplayShape(face, update=True)
        start_display()

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc1NTM4NA_size_16_color_FFFFFF_t_70 1]

#### 扫略 ####

from OCC.Core.GeomFill import GeomFill_Pipe
    from OCC.Core.gp import gp_Pnt
    from OCC.Core.BRepBuilderAPI import BRepBuilderAPI_MakeFace, BRepBuilderAPI_MakeEdge, BRepBuilderAPI_MakeWire
    from OCC.Core.TColgp import TColgp_Array2OfPnt, TColgp_HArray1OfPnt
    from OCC.Core.GeomAPI import GeomAPI_PointsToBSplineSurface, GeomAPI_PointsToBSpline, GeomAPI_Interpolate
    from OCC.Core.GeomAbs import GeomAbs_C2
    
    
    Linearray2 = TColgp_HArray1OfPnt(1, 5)
    Linearray2.SetValue(1, gp_Pnt(8, 0, 5))
    Linearray2.SetValue(2, gp_Pnt(7, 1.7, 5))
    Linearray2.SetValue(3, gp_Pnt(6, 2.4, 5))
    Linearray2.SetValue(4, gp_Pnt(3, 3.2, 5))
    Linearray2.SetValue(5, gp_Pnt(1, 5, 5))
    bspline_12 = GeomAPI_Interpolate(Linearray2, False, 0.00001)
    bspline_12.Perform()
    bspline_22 = bspline_12.Curve()
    bspline_32 = BRepBuilderAPI_MakeEdge(bspline_22)
    bspline2 = BRepBuilderAPI_MakeWire(bspline_32.Edge()).Wire()
    
    tube=GeomFill_Pipe(bspline_22,1)
    tube.Perform()
    
    if __name__ == "__main__":
        from OCC.Display.SimpleGui import init_display
        display, start_display, add_menu, add_function_to_menu = init_display()
        display.DisplayShape(tube.Surface(), update=True)
    
        start_display()

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc1NTM4NA_size_16_color_FFFFFF_t_70 2]

--------------------

参考文献：1. [https://opencascade.blogspot.com/][https_opencascade.blogspot.com]  
2. [https://wenku.baidu.com/view/888c8ad3360cba1aa911da01.html][https_wenku.baidu.com_view_888c8ad3360cba1aa911da01.html]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc1NTM4NA_size_16_color_FFFFFF_t_70]: /images/20220123/03a19e9e9bcc404791e040355b825c72.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc1NTM4NA_size_16_color_FFFFFF_t_70 1]: /images/20220123/ce8b2960f6ef4060979bc18ffb9e6915.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc1NTM4NA_size_16_color_FFFFFF_t_70 2]: /images/20220123/28ce4897b4c649a2add183852f1473f8.png
[https_opencascade.blogspot.com]: https://opencascade.blogspot.com/
[https_wenku.baidu.com_view_888c8ad3360cba1aa911da01.html]: https://wenku.baidu.com/view/888c8ad3360cba1aa911da01.html