I am using VTK in my project, and I meet a problem about the coordinate convertion: from display coordinate vs world coordiante.
First, I show a cone and set the window size to (500, 500). Then, I calcualte the world point using the (250, 250) display point. The display point (250, 250) is located in the cone.
picker = vtk.vtkPropPicker()
picker.Pick(250, 250, 0, self.ren)
if picker.GetActor():
coordinate = vtk.vtkCoordinate()
coordinate.SetCoordinateSystemToDisplay()
coordinate.SetValue(250, 250, 0)
position = coordinate.GetComputedWorldValue(self.ren)
self.position = position
I show this point as a red point.
Then, I rotate the screen, and I want to convert the world point as the display point. In my thought, the red point would move along with the cone.
coordinate = vtk.vtkCoordinate()
coordinate.SetCoordinateSystemToWorld()
point = self.position
coordinate.SetValue(point[0], point[1], point[2])
displayCoor = coordinate.GetComputedDisplayValue(self.ren)
However, the red point is seperated from the cone. Is there something wrong with the coordinate convertion?
Any suggestion is appreciated.
The whole code is:
from PyQt5.QtWidgets import *
from PyQt5.QtGui import *
from PyQt5.QtCore import *
import sys, os
import numpy as np
import vtk, qimage2ndarray
class vtkLabel(QLabel):
def __init__(self):
super(vtkLabel, self).__init__()
self.setFixedSize(500, 500)
cone = vtk.vtkConeSource()
mapper = vtk.vtkPolyDataMapper()
mapper.SetInputConnection(cone.GetOutputPort())
actor = vtk.vtkActor()
actor.SetMapper(mapper)
ren = vtk.vtkRenderer()
ren.AddActor(actor)
renWin = vtk.vtkRenderWindow()
renWin.AddRenderer(ren)
renWin.SetOffScreenRendering(1)
imageFilter = vtk.vtkWindowToImageFilter()
imageFilter.SetInput(renWin)
self.ren = ren
self.renWin = renWin
self.imageFilter = imageFilter
def mousePressEvent(self, QMouseEvent):
super().mousePressEvent(QMouseEvent)
pos = QMouseEvent.pos()
x = pos.x()
y = pos.y()
self.lastPos = [x, y]
def mouseReleaseEvent(self, QMouseEvent):
super().mouseReleaseEvent(QMouseEvent)
self.lastPos = None
def mouseMoveEvent(self, QMouseEvent):
super().mouseMoveEvent(QMouseEvent)
pos = QMouseEvent.pos()
x = pos.x()
y = pos.y()
if self.lastPos != None:
if QMouseEvent.buttons() == Qt.RightButton:
dy = self.lastPos[1] - y
center = self.ren.GetCenter()
dyf = dy/center[1]
import math
val = math.pow(1.1, dyf)
self.ren.GetActiveCamera().Dolly(val)
if QMouseEvent.buttons() == Qt.LeftButton:
dx = x - self.lastPos[0]
dy = self.lastPos[1] - y
size = self.renWin.GetSize()
delta_elevation = -20.0 / size[1]
delta_azimuth = -20.0 / size[0]
rxf = dx * delta_azimuth
ryf = dy * delta_elevation
camera = self.ren.GetActiveCamera()
camera.Azimuth(rxf)
camera.Elevation(ryf)
camera.OrthogonalizeViewUp()
self.ren.ResetCameraClippingRange()
self.ren.UpdateLightsGeometryToFollowCamera()
self.ren.Render()
self.calculationForDisplay()
def resizeEvent(self, QMouseEvent):
super().resizeEvent(QMouseEvent)
self.renWin.SetSize(self.width(), self.height())
self.calculationForDisplay()
picker = vtk.vtkPropPicker()
picker.Pick(250, 250, 0, self.ren)
if picker.GetActor():
coordinate = vtk.vtkCoordinate()
coordinate.SetCoordinateSystemToDisplay()
coordinate.SetValue(250, 250, 0)
position = coordinate.GetComputedWorldValue(self.ren)
self.position = position
print('the point is one of the cone point')
else:
raise RuntimeError('the point is not one of the cone point')
def calculationForDisplay(self):
self.renWin.Render()
self.imageFilter.Modified()
self.imageFilter.Update()
displayImg = self.imageFilter.GetOutput()
dims = displayImg.GetDimensions()
from vtk.util.numpy_support import vtk_to_numpy
numImg = vtk_to_numpy(displayImg.GetPointData().GetScalars())
numImg = numImg.reshape(dims[1], dims[0], 3)
numImg = numImg.transpose(0, 1, 2)
numImg = np.flipud(numImg)
displayQImg = qimage2ndarray.array2qimage(numImg)
pixmap = QPixmap.fromImage(displayQImg)
self.pixmap = pixmap
self.update()
def paintEvent(self, QPaintEvent):
super(vtkLabel, self).paintEvent(QPaintEvent)
painter = QPainter(self)
width = self.width()
height = self.height()
painter.drawPixmap(QPoint(0, 0), self.pixmap, QRect(0, 0, width, height))
coordinate = vtk.vtkCoordinate()
coordinate.SetCoordinateSystemToWorld()
point = self.position
coordinate.SetValue(point[0], point[1], point[2])
displayCoor = coordinate.GetComputedDisplayValue(self.ren)
x = displayCoor[0]
y = displayCoor[1]
y = self.height() - y
painter.setPen(QPen(QColor(255, 0, 0), 5))
painter.drawPoint(x, y)
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super(MainWindow, self).__init__(parent)
self.setFixedSize(500, 500)
self.imageLabel = vtkLabel()
self.setCentralWidget(self.imageLabel)
app = QApplication(sys.argv)
window = MainWindow()
window.show()
app.exec_()