Vtk-鼠标位置的世界坐标

Question

是否有可能通过鼠标在x-z平面（y = 0）上的渲染窗口中获得世界坐标？

Answer 1

应该有可能，但是可能需要一些计算。我将从this example开始。抓住鼠标事件，例如鼠标移动或鼠标单击，然后使用vtkCoordinate将其转换为世界坐标。

从示例（不是python，但应该足以使您理解）：

virtual void OnLeftButtonDown() 
    {
      std::cout << "Pressed left mouse button." << std::endl;
      int x = this->Interactor->GetEventPosition()[0];
      int y = this->Interactor->GetEventPosition()[1];
      std::cout << "(x,y) = (" << x << "," << y << ")" << std::endl;
      vtkSmartPointer<vtkCoordinate> coordinate = 
        vtkSmartPointer<vtkCoordinate>::New();
      coordinate->SetCoordinateSystemToDisplay();
      coordinate->SetValue(x,y,0);

      // This doesn't produce the right value if the sphere is zoomed in???
      double* world = coordinate->GetComputedWorldValue(this->Interactor->GetRenderWindow()->GetRenderers()->GetFirstRenderer());
      std::cout << "World coordinate: " << world[0] << ", " << world[1] << ", " << world[2] << std::endl;

      // Forward events
      vtkInteractorStyleTrackballCamera::OnLeftButtonDown();
    }

现在，当您单击获得世界坐标时，您可能需要计算线相机位置与鼠标位置（在世界中）的交点以及它与x-z平面的交点。

Answer 2

我可以用vtkplotter复制它：

from vtkplotter import datadir, Plotter, Point
import vtk

def onLeftClick(mesh):
    vcr = vtk.vtkCoordinate()
    vcr.SetCoordinateSystemToDisplay()
    pt = vcr.GetComputedWorldValue(vp.renderer)
    vp.add(Point(mesh.picked3d, c='red'))
    vp.add(Point(pt, c='white'))
    vp.renderer.ResetCamera()
    print(mesh.picked3d, pt)

vp = Plotter(verbose=0)
vp.load(datadir+"bunny.obj")
vp.mouseLeftClickFunction = onLeftClick
vp.show()

但我不确定这是否是所需的输出