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OCC 矩阵变换
在OpenCADCADE中, 通过gp_Trsf类来进行矩阵变换操作,
采用矩阵在左的方式: 新点 = 变换矩阵 * 点
基本原理如下:
//! Defines a non-persistent transformation in 3D space. //! The following transformations are implemented : //! . Translation, Rotation, Scale //! . Symmetry with respect to a point, a line, a plane. //! Complex transformations can be obtained by combining the //! previous elementary transformations using the method //! Multiply. //! The transformations can be represented as follow : //! //! V1 V2 V3 T XYZ XYZ //! | a11 a12 a13 a14 | | x | | x‘| //! | a21 a22 a23 a24 | | y | | y‘| //! | a31 a32 a33 a34 | | z | = | z‘| //! | 0 0 0 1 | | 1 | | 1 | //! //! where {V1, V2, V3} defines the vectorial part of the //! transformation and T defines the translation part of the //! transformation. //! This transformation never change the nature of the objects.
gp_Trsf定义了单个平移, 旋转, 缩放, 对称等操作
复杂变换: 需要通过 gp_Trsf乘法来实现, 如:
一个物体要经过 缩放, 旋转, 平移等一系列操作时, 必须定义为
平移 * 旋转 * 缩放
Python示例:
#!/usr/bin/env python # -*- coding:utf-8 -*- import math from OCC.gp import (gp_Pnt2d, gp_Vec2d, gp_Pnt, gp_Vec, gp_Ax1, gp_OX, gp_OY, gp_OZ, gp_Trsf) atranslation = gp_Trsf() atranslation.SetTranslation(gp_Vec(1, 1, 1)) arotate = gp_Trsf() arotate.SetRotation(gp_OZ(), math.pi) atransform = atranslation * arotate def test1(): print(‘测试1, 平移 -> 旋转‘) pt = gp_Pnt(-1, -1, -1) print(pt.Coord()) pt2 = pt.Transform(atranslation) print(pt.Coord()) pt2 = pt.Transform(arotate) print(pt.Coord()) def test2(): print(‘测试2, 平移 * 旋转‘) pt = gp_Pnt(-1, -1, -1) print(pt.Coord()) pt2 = pt.Transform(atranslation * arotate) print(pt.Coord()) def test3(): print(‘测试3, 旋转 -> 平移‘) pt = gp_Pnt(-1, -1, -1) print(pt.Coord()) pt2 = pt.Transform(arotate) print(pt.Coord()) pt2 = pt.Transform(atranslation) print(pt.Coord()) def test4(): print(‘测试4, 旋转 * 平移‘) pt = gp_Pnt(-1, -1, -1) print(pt.Coord()) pt2 = pt.Transform(arotate * atranslation) print(pt.Coord()) if __name__ == ‘__main__‘: test1() test2() test3() test4()
输出结果为:
测试1, 平移 -> 旋转 (-1.0, -1.0, -1.0) (0.0, 0.0, 0.0) (0.0, 0.0, 0.0) 测试2, 平移 * 旋转 (-1.0, -1.0, -1.0) (2.0, 2.0, 0.0) 测试3, 旋转 -> 平移 (-1.0, -1.0, -1.0) (1.0000000000000002, 0.9999999999999999, -1.0) (2.0, 2.0, 0.0) 测试4, 旋转 * 平移 (-1.0, -1.0, -1.0) (0.0, 0.0, 0.0)
OCC 矩阵变换
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