catalogue

VTK compilation and environment construction

VTK general rendering process

VTK data type - vtkPolyData

Use vtk's own polygon data

Use your own data

Add vertex color

Add face color

VTK compilation and environment construction

At present, some leaders have made mature fool configuration for this part. You can refer to this article: VTK + vs2019 (or other versions are available) fool type one-stop configuration_ Nancy_ Fair's blog - CSDN blog_ vs2019 vtk

VTK general rendering process

There are also many introductions in this part. You can refer to this article: vtk notes - learn about vtk_ Heishan old demon's blog - CSDN blog_ vtk application field recently, I relearned vtk related content, and the quality of online data is uneven. I collected data from many places and sorted out records; vtk (Visualization Toolkit) is an open source free software system, which is mainly used for three-dimensional computer graphics, image processing and visualization. vtk is designed and implemented on the basis of object-oriented principle. Its kernel is built in C + +. It contains about 250000 lines of code, more than 2000 classes and several conversion interfaces. Therefore, vtk can also be used freely through various languages such as Java, Tcl/Tk and Python. Visualization Toolkit (vtk)https://blog.csdn.net/liushao1031177/article/details/115503446

VTK data type - vtkPolyData

Polygon dataset is mainly composed of vertices, multi vertices, lines, polylines and triangular zones.
Vertices, lines, and polygons constitute the smallest set of basic elements used to represent 0, 1, and 2-dimensional geometry. In particular, the triangle belt only needs N+2 points to express N triangles, and most graphics render the triangle belt very fast.

Use vtk's own polygon data

vtk comes with a lot of mature polygon data, including cylinder, sphere, cone and so on. We only need to set a few properties to create a model and display it with ready-made data. The following is the code for creating a display cone

void SimpleVtk()
{
	vtkConeSource* source = vtkConeSource::New();
	source->SetHeight(13);
	source->SetRadius(5);

	vtkPolyDataMapper* coneMapper = vtkPolyDataMapper::New();
	coneMapper->SetInputConnection(source->GetOutputPort());

	vtkActor* coneActor = vtkActor::New();
	coneActor->SetMapper(coneMapper);

	vtkRenderer* render = vtkRenderer::New();
	vtkRenderWindow* renwin = vtkRenderWindow::New();
	vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();

	render->AddActor(coneActor);
	render->SetBackground(0.8, 0.4, 0.4);

	renwin->AddRenderer(render);

	iren->SetRenderWindow(renwin);
	iren->Initialize();
	iren->Start();

	source->Delete();
	coneMapper->Delete();
	coneActor->Delete();
	render->Delete();
	renwin->Delete();
	iren->Delete();
}

First create the cone resource and set its properties, then pass it to the mapper, which passes the results to the rendering component for rendering display. The following are the results of the run:

Use your own data

Of course, sometimes the default model is not enough. We want to create the model ourselves. The following is the code for creating a tetrahedron:

void makePolyData()
{
	vtkPoints* points = vtkPoints::New();
	points->InsertNextPoint(0.0, 0.0, 0.0);
	points->InsertNextPoint(1.0, 0.0, 0.0);
	points->InsertNextPoint(0.0, 1.0, 0.0);
	points->InsertNextPoint(0.0, 0.0, 1.0);

	vtkTriangle* tran1 = vtkTriangle::New();
	tran1->GetPointIds()->SetId(0, 0);
	tran1->GetPointIds()->SetId(1, 1);
	tran1->GetPointIds()->SetId(2, 2);
	
	vtkTriangle* tran2 = vtkTriangle::New();
	tran2->GetPointIds()->SetId(0, 0);
	tran2->GetPointIds()->SetId(1, 1);
	tran2->GetPointIds()->SetId(2, 3);

	vtkTriangle* tran3 = vtkTriangle::New();
	tran3->GetPointIds()->SetId(0, 0);
	tran3->GetPointIds()->SetId(1, 2);
	tran3->GetPointIds()->SetId(2, 3);

	vtkTriangle* tran4 = vtkTriangle::New();
	tran4->GetPointIds()->SetId(0, 1);
	tran4->GetPointIds()->SetId(1, 2);
	tran4->GetPointIds()->SetId(2, 3);

	vtkCellArray* cells = vtkCellArray::New();
	cells->InsertNextCell(tran1);
	cells->InsertNextCell(tran2);
	cells->InsertNextCell(tran3);
	cells->InsertNextCell(tran4);

	vtkPolyData* source = vtkPolyData::New();
	source->SetPoints(points);
	source->SetPolys(cells);

	vtkPolyDataMapper* coneMapper = vtkPolyDataMapper::New();
	coneMapper->SetInputData(source);

	vtkActor* coneActor = vtkActor::New();
	coneActor->SetMapper(coneMapper);

	vtkRenderer* render = vtkRenderer::New();
	vtkRenderWindow* renwin = vtkRenderWindow::New();
	vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();

	render->AddActor(coneActor);
	render->SetBackground(0.8, 0.4, 0.4);

	renwin->AddRenderer(render);

	iren->SetRenderWindow(renwin);
	iren->Initialize();
	iren->Start();

	points->Delete();
	tran1->Delete();
	tran2->Delete();
	tran3->Delete();
	tran4->Delete();
	cells->Delete();
	source->Delete();
	coneMapper->Delete();
	coneActor->Delete();
	render->Delete();
	renwin->Delete();
	iren->Delete();
}

Firstly, create point resources and add coordinate points through InsertNextPoint method. Secondly, create four triangles of tetrahedron, set the index of points through getpointids() - > setid() method, and then add the four triangles into polygon cells through InsertNextCell method. Then add point resources and polygon cells to vtkPolyData, and put the Data into the rendering process to display the tetrahedron. The following are the output results:

Obviously, this generation method is a little cumbersome. vtk you can add triangular bands into polygon cells. Generally, 3D models are composed of triangular bands, which save resources and render quickly. The following is the code of the triangle belt:

void makePolyData2()
{
	vtkPoints* points = vtkPoints::New();
	points->InsertNextPoint(0.0, 0.0, 0.0);
	points->InsertNextPoint(1.0, 0.0, 0.0);
	points->InsertNextPoint(0.0, 1.0, 0.0);
	points->InsertNextPoint(0.0, 0.0, 1.0);

	vtkCellArray* array = vtkCellArray::New();
	array->InsertNextCell(6);

	array->InsertCellPoint(1);
	array->InsertCellPoint(3);
	array->InsertCellPoint(0);
	array->InsertCellPoint(2);
	array->InsertCellPoint(1);
	array->InsertCellPoint(3);

	vtkPolyData* source = vtkPolyData::New();
	source->SetPoints(points);
	source->SetStrips(array);

	vtkPolyDataMapper* coneMapper = vtkPolyDataMapper::New();
	coneMapper->SetInputData(source);

	vtkActor* coneActor = vtkActor::New();
	coneActor->SetMapper(coneMapper);

	vtkRenderer* render = vtkRenderer::New();
	vtkRenderWindow* renwin = vtkRenderWindow::New();
	vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();

	render->AddActor(coneActor);
	render->SetBackground(0.8, 0.4, 0.4);

	renwin->AddRenderer(render);

	iren->SetRenderWindow(renwin);
	iren->Initialize();
	iren->Start();

	points->Delete();
	array->Delete();
	source->Delete();
	coneMapper->Delete();
	coneActor->Delete();
	render->Delete();
	renwin->Delete();
	iren->Delete();
}

Use InsertCellPoint method to add the index of the point to the triangle belt, and use SetStrips to add the triangle belt in the resource. The following is the rendering result:

Add vertex color

Now that we have successfully generated the tetrahedron, it is gray and obviously not very good-looking. The following is the code for adding color display. First, add vertex color:

void makePolyDataAndSetColor()
{
	unsigned char red[3] = { 255, 0, 0 };
	unsigned char green[3] = { 0, 255, 0 };
	unsigned char blue[3] = { 0, 0, 255 };

	vtkPoints* points = vtkPoints::New();
	points->InsertNextPoint(0.0, 0.0, 0.0);
	points->InsertNextPoint(1.0, 0.0, 0.0);
	points->InsertNextPoint(0.0, 1.0, 0.0);
	points->InsertNextPoint(0.0, 0.0, 1.0);

	vtkCellArray* array = vtkCellArray::New();
	array->InsertNextCell(6);

	array->InsertCellPoint(1);
	array->InsertCellPoint(3);
	array->InsertCellPoint(0);
	array->InsertCellPoint(2);
	array->InsertCellPoint(1);
	array->InsertCellPoint(3);

	vtkUnsignedCharArray* pointsColors = vtkUnsignedCharArray::New();
	pointsColors->SetNumberOfComponents(3);
	pointsColors->InsertNextTypedTuple(red);
	pointsColors->InsertNextTypedTuple(green);
	pointsColors->InsertNextTypedTuple(blue);
	pointsColors->InsertNextTypedTuple(red);

	vtkPolyData* source = vtkPolyData::New();
	source->SetPoints(points);
	source->SetStrips(array);
	source->GetPointData()->SetScalars(pointsColors);

	vtkPolyDataMapper* coneMapper = vtkPolyDataMapper::New();
	coneMapper->SetInputData(source);

	vtkActor* coneActor = vtkActor::New();
	coneActor->SetMapper(coneMapper);

	vtkRenderer* render = vtkRenderer::New();
	vtkRenderWindow* renwin = vtkRenderWindow::New();
	vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();

	render->AddActor(coneActor);
	render->SetBackground(0.8, 0.4, 0.4);

	renwin->AddRenderer(render);

	iren->SetRenderWindow(renwin);
	iren->Initialize();
	iren->Start();

	points->Delete();
	array->Delete();
	pointsColors->Delete();
	source->Delete();
	coneMapper->Delete();
	coneActor->Delete();
	render->Delete();
	renwin->Delete();
	iren->Delete();
}

Create a new unsigned char array as the color resource, and add the color to the color resource through the InsertNextTypedTuple() method. Then add vertex color resources to polyData through getpointdata() - > setscalars() method. The following is the rendering result:

Add face color

Of course, we can also add solid colors to each face:

void makePolyDataAndSetColor2()
{
	unsigned char red[3] = { 255, 0, 0 };
	unsigned char green[3] = { 0, 255, 0 };
	unsigned char blue[3] = { 0, 0, 255 };

	vtkPoints* points = vtkPoints::New();
	points->InsertNextPoint(0.0, 0.0, 0.0);
	points->InsertNextPoint(1.0, 0.0, 0.0);
	points->InsertNextPoint(0.0, 1.0, 0.0);
	points->InsertNextPoint(0.0, 0.0, 1.0);

	vtkTriangle* tran1 = vtkTriangle::New();
	tran1->GetPointIds()->SetId(0, 0);
	tran1->GetPointIds()->SetId(1, 1);
	tran1->GetPointIds()->SetId(2, 2);

	vtkTriangle* tran2 = vtkTriangle::New();
	tran2->GetPointIds()->SetId(0, 0);
	tran2->GetPointIds()->SetId(1, 1);
	tran2->GetPointIds()->SetId(2, 3);

	vtkTriangle* tran3 = vtkTriangle::New();
	tran3->GetPointIds()->SetId(0, 0);
	tran3->GetPointIds()->SetId(1, 2);
	tran3->GetPointIds()->SetId(2, 3);

	vtkTriangle* tran4 = vtkTriangle::New();
	tran4->GetPointIds()->SetId(0, 1);
	tran4->GetPointIds()->SetId(1, 2);
	tran4->GetPointIds()->SetId(2, 3);

	vtkCellArray* cells = vtkCellArray::New();
	cells->InsertNextCell(tran1);
	cells->InsertNextCell(tran2);
	cells->InsertNextCell(tran3);
	cells->InsertNextCell(tran4);

	vtkUnsignedCharArray* cellColors = vtkUnsignedCharArray::New();
	cellColors->SetNumberOfComponents(3);
	cellColors->InsertNextTypedTuple(red);
	cellColors->InsertNextTypedTuple(green);
	cellColors->InsertNextTypedTuple(blue);
	cellColors->InsertNextTypedTuple(red);

	vtkPolyData* source = vtkPolyData::New();
	source->SetPoints(points);
	source->SetPolys(cells);
	source->GetCellData()->SetScalars(cellColors);

	vtkPolyDataMapper* coneMapper = vtkPolyDataMapper::New();
	coneMapper->SetInputData(source);

	vtkActor* coneActor = vtkActor::New();
	coneActor->SetMapper(coneMapper);

	vtkRenderer* render = vtkRenderer::New();
	vtkRenderWindow* renwin = vtkRenderWindow::New();
	vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();

	render->AddActor(coneActor);
	render->SetBackground(0.8, 0.4, 0.4);

	renwin->AddRenderer(render);

	iren->SetRenderWindow(renwin);
	iren->Initialize();
	iren->Start();

	points->Delete();
	cellColors->Delete();
	tran1->Delete();
	tran2->Delete();
	tran3->Delete();
	tran4->Delete();
	cells->Delete();
	source->Delete();
	coneMapper->Delete();
	coneActor->Delete();
	render->Delete();
	renwin->Delete();
	iren->Delete();
}

This time, the getcelldata() - > setscalars() method is used to transfer the face color to each face. The rendering results are as follows:

You can also try to add vertex color and face color at the same time.