July 2022 – weiy.city

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 Webassembly. After reading the source code of vtkOrientedGlyphContourRepresentation::vtkOrientedGlyphContourRepresentation(), we know Read more…

By StephenWei, 3 years2022-07-27 ago

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 algorithm can’t be rendered in WebGL because something is wrong Read more…

By StephenWei, 3 years2022-07-27 ago

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 crash on our web page. Output: It seems something wrong Read more…

By StephenWei, 3 years2022-07-21 ago

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. Because U Read more…

By StephenWei, 3 years2022-07-20 ago

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:

By StephenWei, 3 years2022-07-19 ago

Shell

Extract The First Two Layers Of Zip Files

If you have a few zip files in a folder, and the zip file had compressed some child zips, the following shell script can help you to extract them. The compressed information in our example look like: Shell script: #! /usr/bin/bash # find zips in current path files=() find . Read more…

By StephenWei, 3 years2022-07-19 ago

Shell

Shell Script – Rename Files’ Suffixes Recursively And Find Folders

Rename Files’ Suffixes Recursively And Find Folders Find Folders To find all folders in the current path, I wrote a simple shell script file. It ignores invisible folder which path looks like ./.XXX. #! /usr/bin/bash dirs=() find . -type d -print0 >tmpfile while IFS= read -r -d $’\0′; do dirs+=(“$REPLY”) Read more…

By StephenWei, 3 years ago

VTK

VTK – Display 3D Model With Shading

The post shows how to use VTK to display 3D model with shading.We need to make sure the version of VTK is equal to 9 or bigger than it.To avoid the faceted appearance, compute points’ normal to support to has shading at triangle vertices. Demo: Output: The faceted surface of Read more…

By StephenWei, 3 years2022-07-06 ago

VTK

Get Normals Of Points By vtkPolyDataNormals

The post is related to The Example About vtkPolyDataNormals. If you want to use vtkPolyDataNormals to compute the normals of points, it’s better to set variable Splitting false. #include <vtkVersion.h> #include <vtkSmartPointer.h> #include <vtkSurfaceReconstructionFilter.h> #include <vtkProgrammableSource.h> #include <vtkContourFilter.h> #include <vtkReverseSense.h> #include <vtkPolyDataMapper.h> #include <vtkProperty.h> #include <vtkPolyData.h> #include <vtkCamera.h> #include <vtkRenderer.h> Read more…

By StephenWei, 3 years2022-07-04 ago