volume_raycasting_example.py 文件源码

def pan(self, dx, dy, dz, relative=False):
        """
        Moves the center (look-at) position while holding the camera in place. 

        If relative=True, then the coordinates are interpreted such that x
        if in the global xy plane and points to the right side of the view, y is
        in the global xy plane and orthogonal to x, and z points in the global z
        direction. Distances are scaled roughly such that a value of 1.0 moves
        by one pixel on screen.

        """
        if not relative:
            self.camera_center += QtGui.QVector3D(dx, dy, dz)
        else:
            cPos = self.cameraPosition()
            cVec = self.camera_center - cPos
            dist = cVec.length()  ## distance from camera to center
            xDist = dist * 2. * np.tan(0.5 * self.camera_fov * np.pi / 180.)  ## approx. width of view at distance of center point
            xScale = xDist / self.width()
            zVec = QtGui.QVector3D(0,0,1)
            xVec = QtGui.QVector3D.crossProduct(zVec, cVec).normalized()
            yVec = QtGui.QVector3D.crossProduct(xVec, zVec).normalized()
            self.camera_center = self.camera_center + xVec * xScale * dx + yVec * xScale * dy + zVec * xScale * dz
        self.update()