Affine transformation can be decomposed to translation, rotation, and scale. As we know, the transformation can be represented by matrix. Related post: https://www.weiy.city/2021/11/the-releationship-between-local-transform-and-pose-transform/ It can be computed by translate matrix and rotate & scale matrix. Example: I try to do decomposition for a matrix. Read more…
We know the matrix shearing object along a particular axis looks like: The shear transform can help us to approve that when a normal vector is transformed using the same matrix that transforms the points on an object, the resulting vector may not be perpendicular to the surface Read more…
Here are three vectors (1, 0, 1), (-1, 0, 1) and (0, -1, 0) in the 3D world space. Define a position pos(1, 1, 0). These vector and position forms a new coordinate system A. The inverse result is status B. The original world coordinate system can be changed to Read more…
Here are four points in 3D space, we will take them and generate another four points to draw a cube. Construct triangles to form cells for the mesh, the normal of every cell is toward inside. Here are all details about the generation. Update on 2023.10.17: The cells’ normals generated Read more…
The post is based on https://www.weiy.city/2021/11/vtk-rotate-vector-to-special-direction/. We will rotate the three axes of the world coordinate system to particular directions. #include <iostream> #include <vtkSmartPointer.h> #include <vtkTransform.h> #include <vtkActor.h> #include <vtkConeSource.h> #include <vtkRenderer.h> #include <vtkRenderWindow.h> #include <vtkPolyDataMapper.h> #include <vtkRenderWindowInteractor.h> #include <vtkAxesActor.h> #include “../point.hpp” using namespace std; double AngleBeteewnTwoVector( Point vec0, Point Read more…
I take notes about how to rotate vector to a special direction. #include “./tool.h” #define vtkSPtr vtkSmartPointer #define vtkSPtrNew(Var, Type) vtkSPtr<Type> Var = vtkSPtr<Type>::New(); int main(int, char *[]) { PointStruct vec0( 1, 1, 0 ); PointStruct vec1( -1, 1, 0 ); PointStruct vecZ( 0, 0, 1 ); double radian = Read more…
The post introduces how to create an environment for learning VTK by Python. The basic conditions on my computer: VTK-8.1.1 macOS Mojave 10.14 Python 2.7.10 Write a bash script and run it. cmake ./ -G “Unix Makefiles” \ -DVTK_USE_QVTK:BOOL=ON \ -DCMAKE_INSTALL_PREFIX=/usr/local \ -DVTK_USE_GUISUPPORT:BOOL=ON \ -DVTK_QT_VERSION=5 \ -DModule_vtkGUISupportQt:BOOL=ON \ -DModule_vtkGUISupportQtOpenGL:BOOL=ON \ Read more…
The post shows a way to create 2D grid on screen by VTK. Show it by vtkActor2D because we regard it as a 2D object. Its default coordinate system is viewport which is rendering. So we will have to know the window’s size. Let’s make the process easier. Change the Read more…
I created a 2D convex hull and wanted to check whether a point is inside it. If the point is inside the polygon, the neighbor cross product vectors have the same directions. If the point is outside, one vector is toward the outside, the other one is toward the inside. Read more…