Converting 2D screen coordinates to 3D Coordinates in PyQT - qt

Question

I am using PyQT for one of the first times, and I'm having trouble figuring out where a mouse click is in 3D space. Obviously it is not a perfect 1-to-1 mapping, but let's say that I click on a location (x, y, 0) on my QtGui. How can I transform that mouse click to its 3D location using the camera?
Context: I am trying to have users draw splines in 3-D, and in order to do this, I need to know where the user is clicking for when I render the spline. I'm building an application using PythonOCC. I've attached my code below.
import random
import sys
import IPython
from OCC.Display.qtDisplay import qtViewer3d, get_qt_modules
from OCC.gp import gp_Pnt2d, gp_Pnt
from OCC.BRepBuilderAPI import (BRepBuilderAPI_MakeEdge,
BRepBuilderAPI_MakeVertex,
BRepBuilderAPI_MakeWire)
from OCC.BRepFill import BRepFill_Filling
from OCC.GeomAbs import GeomAbs_C0
from OCC.GeomAPI import GeomAPI_PointsToBSpline
from OCC.TColgp import TColgp_Array1OfPnt
QtCore, QtGui, QtOpenGL = get_qt_modules()
try:
from OpenGL.GL import (glViewport, glMatrixMode, glOrtho, glLoadIdentity,
GL_PROJECTION, GL_MODELVIEW)
except ImportError:
msg = "for this example, the OpenGL module is required" \
"why not run \"pip install PyOpenGL\"\?"
sys.exit(status=1)
class GLWidget(qtViewer3d):
def __init__(self, parent=None):
super(GLWidget, self).__init__(parent)
self._initialized = False
midnight = QtCore.QTime(0, 0, 0)
random.seed(midnight.secsTo(QtCore.QTime.currentTime()))
self.object = 0
self.xRot = 0
self.yRot = 0
self.zRot = 0
self.image = QtGui.QImage()
self.bubbles = []
self.lastPos = QtCore.QPoint()
self.lines = []
self.current_point = None
self.pts = []
self.shiftHeld = True
self.trolltechGreen = QtGui.QColor.fromCmykF(0.40, 0.0, 1.0, 0.0)
self.trolltechPurple = QtGui.QColor.fromCmykF(0.39, 0.39, 0.0, 0.0)
self.animationTimer = QtCore.QTimer()
self.animationTimer.setSingleShot(False)
self.animationTimer.timeout.connect(self.animate)
self.animationTimer.start(25)
self.setAutoFillBackground(False)
self.setMinimumSize(200, 200)
self.setWindowTitle("Overpainting a Scene")
# parameters for overpainting
self.setAttribute(QtCore.Qt.WA_NoSystemBackground, 0)
self.setAttribute(QtCore.Qt.WA_OpaquePaintEvent)
def setXRotation(self, angle):
if angle != self.xRot:
self.xRot = angle
def setYRotation(self, angle):
if angle != self.yRot:
self.yRot = angle
def setZRotation(self, angle):
if angle != self.zRot:
self.zRot = angle
def mousePressEvent(self, event):
self.lastPos = event.pos()
super(GLWidget, self).mousePressEvent(event)
worldCoords = super(GLWidget, self).mapToGlobal( self.lastPos )
print self.lastPos
if event.buttons() & QtCore.Qt.RightButton and not (event.modifiers() & QtCore.Qt.ShiftModifier):
print 'first'
self.pts.append(gp_Pnt(self.lastPos.x(), self.lastPos.y(), 0.0))
elif event.buttons() & QtCore.Qt.RightButton and (event.modifiers() & QtCore.Qt.ShiftModifier):
print 'second'
curve = self.points_to_bspline(self.pts)
self._display.DisplayShape(curve, update=True)
self.pts = [] #clear it
def mouseMoveEvent(self, event):
dx = event.x() - self.lastPos.x()
dy = event.y() - self.lastPos.y()
"""
if (event.buttons() & QtCore.Qt.LeftButton):
self.setXRotation(self.xRot + 8 * dy)
self.setYRotation(self.yRot + 8 * dx)
elif (event.buttons() & QtCore.Qt.RightButton):
self.setXRotation(self.xRot + 8 * dy)
self.setZRotation(self.zRot + 8 * dx)
"""
self.lastPos = event.pos()
super(GLWidget, self).mouseMoveEvent(event)
def paintGL(self):
if self._inited:
self._display.Context.UpdateCurrentViewer()
def paintEvent(self, event):
if self._inited:
self._display.Context.UpdateCurrentViewer()
self.makeCurrent()
painter = QtGui.QPainter(self)
painter.setRenderHint(QtGui.QPainter.Antialiasing)
if self.context().isValid():
self.swapBuffers()
if self._drawbox:
painter.setPen(QtGui.QPen(QtGui.QColor(0, 0, 0), 1))
rect = QtCore.QRect(*self._drawbox)
painter.drawRect(rect)
"""
for bubble in self.bubbles:
if bubble.rect().intersects(QtCore.QRectF(event.rect())):
bubble.drawBubble(painter)
"""
painter.end()
self.doneCurrent()
else:
print('invalid OpenGL context: Qt cannot overpaint viewer')
def showEvent(self, event):
pass
#self.createBubbles(20 - len(self.bubbles))
def sizeHint(self):
return QtCore.QSize(400, 400)
def animate(self):
pass
"""
for bubble in self.bubbles:
bubble.move(self.rect())
self.update()
"""
def setupViewport(self, width, height):
side = min(width, height)
glViewport((width - side) // 2, (height - side) // 2, side, side)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
glOrtho(-0.5, +0.5, +0.5, -0.5, 4.0, 15.0)
glMatrixMode(GL_MODELVIEW)
def points_to_bspline(self, pnts):
pts = TColgp_Array1OfPnt(0, len(pnts)-1)
for n, i in enumerate(pnts):
pts.SetValue(n, i)
crv = GeomAPI_PointsToBSpline(pts)
return crv.Curve()
if __name__ == '__main__':
def TestOverPainting():
class AppFrame(QtGui.QWidget):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.setWindowTitle(self.tr("qtDisplay3d overpainting example"))
self.resize(640, 480)
self.canva = GLWidget(self)
mainLayout = QtGui.QHBoxLayout()
mainLayout.addWidget(self.canva)
mainLayout.setContentsMargins(0, 0, 0, 0)
self.setLayout(mainLayout)
def runTests(self):
self.canva._display.Test()
app = QtGui.QApplication(sys.argv)
frame = AppFrame()
frame.show()
frame.canva.InitDriver()
frame.runTests()
app.exec_()
TestOverPainting()

Answer 1

To answer my own question:
(x, y, z, vx, vy, vz) = self._display.View.ConvertWithProj(self.lastPos.x(), self.lastPos.y())
Gives the entire line of points that x and y can map to, with x, y, and z being one point, and vx, vy, and vz giving the parameterization of the line.