OpenCV
Video – build And Test OpenCV 4.6.0 On Ubuntu 20.04
Here is a video about building OpenCV 4.6.0 on Ubuntu 20.04. It records all process about building OpenCV library and running a simple test program. Youtube: Bilibili:
Web
WASM – Pass Array Between C++ And JS
The post shows how to pass array from javascript to cpp function as parameter and how to use javascript to receive array from cpp function. We have to know the javascript TypedArray objects and different types of emscripten memory model Read more…
Tool
Build Script For VTK And Source.list For Ubuntu 20.04 LTS
The shell script build vtk in the folder build, /home/stephen/Downloads/VTK-9.2.0.rc2/build: 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 \ -DModule_vtkGUISupportQtSQL:BOOL=ON \ -DModule_vtkGUISupportQtWebkit:BOOL=OFF \ -DModule_vtkRenderingQt:BOOL=ON \ -DModule_vtkViewsQt:BOOL=ON The sources.list for Chinese user Read more…
Tool
Image Processing – Rotate Image
We have added a new function to the image processing page: rotate the image clockwise by any angle.我们在图像处理页面增加了一个新的功能：顺时针旋转图片任意角度。 Our picture doesn’t awalys fit on the phone or computer monitor, so we need to put it right. We need to rotate Read more…
VTK
Make vtkContourWidget Object Work On Webassembly Page
I had found a crash bug when use vtkContourWidget by webassembly in the post Crash Bug About vtkOpenGLPolyDataMapper::UpdateShaders In vtkAbstractWidget.As we know, SetResolveCoincidentTopologyToPolygonOffset for mapper can make web page crash, related post: The Interfaces In VTK Can’t Be Used With Read more…
VTK
The Interfaces In VTK Can’t Be Used With Webassembly
The Interfaces In VTK Can’t Be Used With Webassembly Setting point size and line width doesn’t work vtkProperty.h Shift polygons, lines and points will fail in wasm. It will cause crash on web page. The new polydata generated by vtkFeatureEdge Read more…
VTK
Crash Bug About vtkOpenGLPolyDataMapper::UpdateShaders In vtkAbstractWidget
I can’t display vtkContourWidget object on web page by wasm file.The following code snippet is very simple, create a circle and show it, we can modify it by vtkContourWidget object.The example works in CPlusCPlus program.VTK version: 9.0.2. But it will Read more…
Math
The Relationship Between 3D Coordinate Value XYZ And 2D Texture Coordinate UVR
We will introduce the transformation equation for 3D Coordinate Value XYZ And 2D Texture Coordinate UVR. Try to represent the UVR value by x,y, and z. Here is derivation process. Read more…
Shell
Shell Script – Make Function Execute Recursively
In the following example, we will create a function to compute number’s factorial result.Let’s echo in the function to support fetch return value outside. Output: