There is a massive module in my project, it computes many data tasks, update UI, and is responsible for interaction style. I want to move the user interaction part to another viewer class, make the old module more lightweight. The structure of the module class looks like the following snippet. Read more…
We will got the following left part’s effect when zoom in and zoom out in VTK render window. How to keep the same display size for the 3D model cube when zoom in or zoom out? VTK changes camera’s status in the interfaces vtkInteractorStyleTrackballCamera::OnMouseWheelForward and vtkInteractorStyleTrackballCamera::OnMouseWheelBackward, the action Dolly moves Read more…
The article introduces how to display an image by OpenCV in CPlusPlus and Python language. The user can exit the whole program when he presses the ESC key. CPP CMakeLists.txt macro(use_cxx11) if (CMAKE_VERSION VERSION_LESS “3.1”) if (CMAKE_CXX_COMPILER_ID STREQUAL “GNU”) set (CMAKE_CXX_FLAGS “${CMAKE_CXX_FLAGS} -std=gnu++11”) endif () else () set (CMAKE_CXX_STANDARD 11) Read more…
The inital scene is like the following image, here are an axes actor and an irregular 3D model. We want to find all points that are on the model and face the plane which has normal (0, 1, 0) and origin (0, -10, 0). My solution spend a lot time, Read more…
We have to calculate the vector on the special direction firstly. void CalculateVecComponent(PointStruct originVec, PointStruct &axis0, PointStruct &vecOnAxis) { double cosTheta = originVec.Dot( axis0 ); return axis0*cosTheta; } Project point on line Point GetProjectPtOnDir(Point pt, Point dir, Point startPt) { dir.Unit(); Point ptVector = pt – startPt; double cosTheta = Read more…
We can use vtkButtonWidget to create 2D buttons in the render window. The vtkWidgetRepresentation object controls the button’s position and show button pictures. Write our class ButtonCallBack that inherits vtkCommand and use it to listen for vtkCommand::StateChangedEvent, then we can add our button click function in it. Finally, the widget Read more…
Find a local partial region on the surface of the sphere, mark it by red color. Finally, we will compute the normal of the partial region and show it by a green line. The whole scene is just like the following image. Here are a few steps about the process. Read more…
A JSON file stores data objects in JavaScript Object Notation(JSON) format. It’s lightweight and readable, the developer uses it to transmit simple data. The article shows how to create and read the JSON file in the Qt environment. I planed to save two books’ information to a simple JSON file Read more…
The interface vtkObjectBase::UnRegister will reduce the reference count for pointer and delete the pointer if the reference count becomes zero. vtkObjectBase::Delete <= vtkObjectBase::UnRegister <= vtkObjectBase::UnRegisterInternal <= delete ptr vtkSmartPointerBase::~vtkSmartPointerBase { vtkObjectBase* object = this->Object; if(object) { this->Object = nullptr; object->UnRegister(nullptr); } } We can get the reference count and consumer Read more…