This post introduces a way to find the biggest plane on the 3D model. We expand the initial cell by comparing its normal with neighbor’s normal. It indicates they are on a plane if the two normals of cells are approximately equal. I use vtkOBBTree to find the min axes Read more…
The article introduces two ways to calculate the distance from a point to a line. One use dot product by two vectors to get distance vector, and the other use cross product by vectors to achieve it. Let’s assume the point is P, two endpoints of the line are L1 Read more…
We can use vtkImplicitPolyDataDistance to calculate the distance from a point to the target polydata. It’s better than calculating the distance by iterating to the search point. The following example puts a sphere that radius is 1 and origin is (0, 0, 0) in the renderer. Our test point is Read more…
We define all edges in the boundary have no neighbor cells. It indicates that there is no boundary on the closed surface. In the following example, I read an STL file and get an arch. Step 1, clip the original arch with a plane that has normal (0, 1, 0) Read more…
We can find that vtkOrientedGlyphContourRepresentation supports to set 3D model always above other objects. // Create the contour widget vtkSmartPointer<vtkContourWidget> contourWidget = vtkSmartPointer<vtkContourWidget>::New(); // Override the default representation for the contour widget to customize its look vtkSmartPointer<vtkOrientedGlyphContourRepresentation> contourRepresentation = vtkSmartPointer<vtkOrientedGlyphContourRepresentation>::New(); // … contourWidget->SetRepresentation(contourRepresentation); contourRepresentation->SetAlwaysOnTop( true ); I readed the code Read more…
We want to know the height of the above cone, there is the precondition that there is a red sphere in the center of the cone and we assume that we can’t get the height from multiplying the length of the vector both red spheres forms by 2. The original Read more…
The article shows a way to calculate the length between two points on a curve. We create a ring and put axis actor in the center to show the ring’s orientation and size. Here are implementation details, the data file curve.vtp can be downloaded from my github repository documents. #define Read more…
How to set different colors for different parts of a single 3D model? The article introduces a way that set scalars for pointData and map the information by vtkColorTransferFunction object, then vtkPolyDataMapper object configure a correct scalar mode and use vtkColorTransferFunction object as its lookupTable. The code snippet shows all Read more…
I want to rotate the curve to be close to both points, the rotate axis is vector( 0, 0, 1 ) which is Z-axis in VTK’s world coordinate system. We can use the summary of distance squares to indicate the match level, the value is bigger means the curve is Read more…