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# Source code for pyqtgraph.opengl.GLViewWidget

    from math import cos, radians, sin, tan
    import importlib
    import warnings

    from OpenGL import GL
    import numpy as np

    from .. import Vector
    from .. import functions as fn
    from .. import getConfigOption
    from ..Qt import QtCore, QtGui, QtWidgets, QT_LIB

    if QT_LIB in ["PyQt5", "PySide2"]:
        QtOpenGL = QtGui
    else:
        QtOpenGL = importlib.import_module(f"{QT_LIB}.QtOpenGL")

    class GLViewMixin:

        def __init__(self, *args, rotationMethod='euler', **kwargs):
            """
            Mixin class providing functionality for GLViewWidget

            ================ ==============================================================
            **Arguments:**
            rotationMethod   (str): Mechanism to drive the rotation method, options are
                             'euler' and 'quaternion'. Defaults to 'euler'.
            ================ ==============================================================
            """
            super().__init__(*args, **kwargs)

            if rotationMethod not in ["euler", "quaternion"]:
                raise ValueError("Rotation method should be either 'euler' or 'quaternion'")

            self.opts = {
                'rotationMethod': rotationMethod
            }
            self.reset()
            self.items = []

            self.noRepeatKeys = [QtCore.Qt.Key.Key_Right, QtCore.Qt.Key.Key_Left, QtCore.Qt.Key.Key_Up, QtCore.Qt.Key.Key_Down, QtCore.Qt.Key.Key_PageUp, QtCore.Qt.Key.Key_PageDown]
            self.keysPressed = {}
            self.keyTimer = QtCore.QTimer()
            self.keyTimer.timeout.connect(self.evalKeyState)

            self._modelViewStack = []
            self._projectionStack = []
            self.default_vao = QtOpenGL.QOpenGLVertexArrayObject(self)

        def deviceWidth(self):
            dpr = self.devicePixelRatioF()
            return int(self.width() * dpr)

        def deviceHeight(self):
            dpr = self.devicePixelRatioF()
            return int(self.height() * dpr)

        def reset(self):
            """
            Initialize the widget state or reset the current state to the original state.
            """
            self.opts['center'] = Vector(0,0,0)  ## will always appear at the center of the widget
            self.opts['distance'] = 10.0         ## distance of camera from center
            self.opts['fov'] = 60                ## horizontal field of view in degrees

            if self.opts['rotationMethod'] == 'quaternion':
                self.opts['rotation'] = QtGui.QQuaternion(1,0,0,0)  ## camera rotation (quaternion:wxyz)
            else:
                self.opts['elevation'] = 30      ## camera's angle of elevation in degrees
                self.opts['azimuth'] = 45        ## camera's azimuthal angle in degrees
                                                 ## (rotation around z-axis 0 points along x-axis)

            self.setBackgroundColor(getConfigOption('background'))

        def addItem(self, item):
            self.items.append(item)

            if self.isValid():
                item.initialize()

            item._setView(self)
            self.update()

        def removeItem(self, item):
            """
            Remove the item from the scene.
            """
            self.items.remove(item)
            item._setView(None)
            self.update()

        def clear(self):
            """
            Remove all items from the scene.
            """
            for item in self.items:
                item._setView(None)
            self.items = []
            self.update()

        def initializeGL(self):
            """
            Initialize items that were not initialized during addItem().
            """
            ctx = self.context()
            fmt = ctx.format()
            if ctx.isOpenGLES():
                warnings.warn(
                    f"pyqtgraph.opengl is primarily tested against OpenGL Desktop"
                    f" but OpenGL {fmt.version()} ES detected",
                    RuntimeWarning,
                    stacklevel=2
                )
            elif fmt.version() < (2, 1):
                verString = GL.glGetString(GL.GL_VERSION)
                raise RuntimeError(
                    "pyqtgraph.opengl: Requires >= OpenGL 2.1; Found %s" % verString
                )

            # Core profile requires a non-default VAO
            if fmt.profile() == QtGui.QSurfaceFormat.OpenGLContextProfile.CoreProfile:
                if not self.default_vao.isCreated():
                    self.default_vao.create()
                    self.default_vao.bind()

            for item in self.items:
                if not item.isInitialized():
                    item.initialize()

        def setBackgroundColor(self, *args, **kwds):
            """
            Set the background color of the widget. Accepts the same arguments as
            :func:`~pyqtgraph.mkColor`.
            """
            self.opts['bgcolor'] = fn.mkColor(*args, **kwds).getRgbF()
            self.update()

        def getViewport(self):
            return (0, 0, self.width(), self.height())

        def setProjection(self, region, viewport):
            m = self.projectionMatrix(region, viewport)
            self._projectionStack.clear()
            self._projectionStack.append(m)

        def projectionMatrix(self, region, viewport):
            x0, y0, w, h = viewport
            dist = self.opts['distance']
            fov = self.opts['fov']
            nearClip = dist * 0.001
            farClip = dist * 1000.

            r = nearClip * tan(0.5 * radians(fov))
            t = r * h / w

            ## Note that X0 and width in these equations must be the values used in viewport
            left  = r * ((region[0]-x0) * (2.0/w) - 1)
            right = r * ((region[0]+region[2]-x0) * (2.0/w) - 1)
            bottom = t * ((region[1]-y0) * (2.0/h) - 1)
            top    = t * ((region[1]+region[3]-y0) * (2.0/h) - 1)

            tr = QtGui.QMatrix4x4()
            tr.frustum(left, right, bottom, top, nearClip, farClip)
            return tr

        def setModelview(self):
            m = self.viewMatrix()
            self._modelViewStack.clear()
            self._modelViewStack.append(m)

        def viewMatrix(self):
            tr = QtGui.QMatrix4x4()
            tr.translate( 0.0, 0.0, -self.opts['distance'])
            if self.opts['rotationMethod'] == 'quaternion':
                tr.rotate(self.opts['rotation'])
            else:
                # default rotation method
                tr.rotate(self.opts['elevation']-90, 1, 0, 0)
                tr.rotate(self.opts['azimuth']+90, 0, 0, -1)
            center = self.opts['center']
            tr.translate(-center.x(), -center.y(), -center.z())
            return tr

        def currentModelView(self):
            return self._modelViewStack[-1]

        def currentProjection(self):
            return self._projectionStack[-1]

        def itemsAt(self, region=None):
            """
            Return a list of the items displayed in the region (x, y, w, h)
            relative to the widget.
            """
            region = (region[0], self.height()-(region[1]+region[3]), region[2], region[3])
            viewport = self.getViewport()

            #buf = np.zeros(100000, dtype=np.uint)
            buf = GL.glSelectBuffer(100000)
            try:
                GL.glRenderMode(GL.GL_SELECT)
                GL.glInitNames()
                GL.glPushName(0)
                self._itemNames = {}
                self.paint(region=region, viewport=viewport, useItemNames=True)

            finally:
                hits = GL.glRenderMode(GL.GL_RENDER)

            items = [(h.near, h.names[0]) for h in hits]
            items.sort(key=lambda i: i[0])
            return [self._itemNames[i[1]] for i in items]

        def paintGL(self):
            # when called by Qt, glViewport has already been called
            # with device pixel ratio taken of
            region = self.getViewport()
            self.paint(region=region, viewport=region)

        def paint(self, *, region, viewport, useItemNames=False):
            """
            It is caller's responsibility to call glViewport prior to calling this method.
            region specifies the sub-region of viewport that should be rendered.
            """
            self.setProjection(region, viewport)
            self.setModelview()
            bgcolor = self.opts['bgcolor']
            GL.glClearColor(*bgcolor)
            GL.glClear( GL.GL_DEPTH_BUFFER_BIT | GL.GL_COLOR_BUFFER_BIT )
            self.drawItemTree(useItemNames=useItemNames)

        def drawItemTree(self, item=None, useItemNames=False):
            if item is None:
                items = [x for x in self.items if x.parentItem() is None]
            else:
                items = item.childItems()
                items.append(item)
            items.sort(key=lambda a: a.depthValue())
            for i in items:
                if not i.visible():
                    continue
                if i is item:
                    try:
                        if useItemNames:
                            GL.glLoadName(i._id)
                            self._itemNames[i._id] = i

                        # The GLGraphicsItem(s) making use of QPainter end
                        # up indirectly unbinding the default VAO, so we
                        # rebind it before each GLGraphicsItem.
                        if self.default_vao.isCreated():
                            self.default_vao.bind()

                        i.paint()
                    except:
                        from .. import debug
                        debug.printExc()
                        print("Error while drawing item %s." % str(item))
                else:
                    self._modelViewStack.append(self.currentModelView() * i.transform())
                    try:
                        self.drawItemTree(i, useItemNames=useItemNames)
                    finally:
                        self._modelViewStack.pop()

        def setCameraPosition(self, pos=None, distance=None, elevation=None, azimuth=None, rotation=None):
            if rotation is not None:
                # Alternatively, we could define that rotation overrides elevation and azimuth
                if elevation is not None:
                    raise ValueError("cannot set both rotation and elevation")
                if azimuth is not None:
                    raise ValueError("cannot set both rotation and azimuth")

            if pos is not None:
                self.opts['center'] = pos
            if distance is not None:
                self.opts['distance'] = distance

            if self.opts['rotationMethod'] == "quaternion":
                # note that "quaternion" mode modifies only opts['rotation']
                if elevation is not None or azimuth is not None:
                    eu = self.opts['rotation'].toEulerAngles()
                    if azimuth is not None:
                        eu.setZ(-azimuth-90)
                    if elevation is not None:
                        eu.setX(elevation-90)
                    self.opts['rotation'] = QtGui.QQuaternion.fromEulerAngles(eu)
                if rotation is not None:
                    self.opts['rotation'] = rotation
            else:
                # note that "euler" mode modifies only opts['elevation'] and opts['azimuth']
                if elevation is not None:
                    self.opts['elevation'] = elevation
                if azimuth is not None:
                    self.opts['azimuth'] = azimuth
                if rotation is not None:
                    eu = rotation.toEulerAngles()
                    self.opts['elevation'] = eu.x() + 90
                    self.opts['azimuth'] = -eu.z() - 90

            self.update()

        def cameraPosition(self):
            """Return current position of camera based on center, dist, elevation, and azimuth"""
            center = self.opts['center']
            dist = self.opts['distance']
            if self.opts['rotationMethod'] == "quaternion":
                pos = Vector(center - self.opts['rotation'].rotatedVector(Vector(0,0,dist) ))
            else:
                # using 'euler' rotation method
                elev = radians(self.opts['elevation'])
                azim = radians(self.opts['azimuth'])
                pos = Vector(
                    center.x() + dist * cos(elev) * cos(azim),
                    center.y() + dist * cos(elev) * sin(azim),
                    center.z() + dist * sin(elev)
                )
            return pos

        def setCameraParams(self, **kwds):
            valid_keys = {'center', 'rotation', 'distance', 'fov', 'elevation', 'azimuth'}
            if not valid_keys.issuperset(kwds):
                raise ValueError(f'valid keywords are {valid_keys}')

            self.setCameraPosition(pos=kwds.get('center'), distance=kwds.get('distance'),
                                   elevation=kwds.get('elevation'), azimuth=kwds.get('azimuth'),
                                   rotation=kwds.get('rotation'))
            if 'fov' in kwds:
                self.opts['fov'] = kwds['fov']

        def cameraParams(self):
            valid_keys = ['center', 'distance', 'fov']

            if self.opts['rotationMethod'] == 'quaternion':
                valid_keys.append('rotation')
            else:
                valid_keys.extend(['elevation', 'azimuth'])

            return { k : self.opts[k] for k in valid_keys }

        def orbit(self, azim, elev):
            """Orbits the camera around the center position. *azim* and *elev* are given in degrees."""
            if self.opts['rotationMethod'] == 'quaternion':
                q = QtGui.QQuaternion.fromEulerAngles(
                        elev, -azim, 0
                        ) # rx-ry-rz
                q *= self.opts['rotation']
                self.opts['rotation'] = q
            else: # default euler rotation method
                self.opts['azimuth'] += azim
                self.opts['elevation'] = fn.clip_scalar(self.opts['elevation'] + elev, -90., 90.)
            self.update()

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

            ==============  =======================================================
            **Arguments:**
            *dx*            Distance to pan in x direction
            *dy*            Distance to pan in y direction
            *dz*            Distance to pan in z direction
            *relative*      String that determines the direction of dx,dy,dz.
                            If "global", then the global coordinate system is used.
                            If "view", then the z axis is aligned with the view
                            direction, and x and y axes are in the plane of the
                            view: +x points right, +y points up.
                            If "view-upright", then x is 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 relative == 'global':
                self.opts['center'] += QtGui.QVector3D(dx, dy, dz)
            elif relative == 'view-upright':
                cPos = self.cameraPosition()
                cVec = self.opts['center'] - cPos
                dist = cVec.length()  ## distance from camera to center
                xDist = dist * 2. * tan(0.5 * radians(self.opts['fov']))  ## 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.opts['center'] = self.opts['center'] + xVec * xScale * dx + yVec * xScale * dy + zVec * xScale * dz
            elif relative == 'view':
                # pan in plane of camera

                if self.opts['rotationMethod'] == 'quaternion':
                    # obtain basis vectors
                    qc = self.opts['rotation'].conjugated()
                    xv = qc.rotatedVector( Vector(1,0,0) )
                    yv = qc.rotatedVector( Vector(0,1,0) )
                    zv = qc.rotatedVector( Vector(0,0,1) )

                    scale_factor = self.pixelSize( self.opts['center'] )

                    # apply translation
                    self.opts['center'] += scale_factor * (xv*-dx + yv*dy + zv*dz)
                else: # use default euler rotation method
                    elev = radians(self.opts['elevation'])
                    azim = radians(self.opts['azimuth'])
                    fov = radians(self.opts['fov'])
                    dist = (self.opts['center'] - self.cameraPosition()).length()
                    fov_factor = tan(fov / 2) * 2
                    scale_factor = dist * fov_factor / self.width()
                    z = scale_factor * cos(elev) * dy
                    x = scale_factor * (sin(azim) * dx - sin(elev) * cos(azim) * dy)
                    y = scale_factor * (cos(azim) * dx + sin(elev) * sin(azim) * dy)
                    self.opts['center'] += QtGui.QVector3D(x, -y, z)
            else:
                raise ValueError("relative argument must be global, view, or view-upright")

            self.update()

        def pixelSize(self, pos):
            """
            Return the approximate size of a screen pixel at the location pos
            Pos may be a Vector or an (N,3) array of locations
            """
            cam = self.cameraPosition()
            if isinstance(pos, np.ndarray):
                cam = np.array(cam).reshape((1,)*(pos.ndim-1)+(3,))
                dist = ((pos-cam)**2).sum(axis=-1)**0.5
            else:
                dist = (pos-cam).length()
            xDist = dist * 2. * tan(0.5 * radians(self.opts['fov']))
            return xDist / self.width()

        def mousePressEvent(self, ev):
            lpos = ev.position() if hasattr(ev, 'position') else ev.localPos()
            self.mousePos = lpos

        def mouseMoveEvent(self, ev):
            lpos = ev.position() if hasattr(ev, 'position') else ev.localPos()
            if not hasattr(self, 'mousePos'):
                self.mousePos = lpos
            diff = lpos - self.mousePos
            self.mousePos = lpos

            if ev.buttons() == QtCore.Qt.MouseButton.LeftButton:
                if (ev.modifiers() & QtCore.Qt.KeyboardModifier.ControlModifier):
                    self.pan(diff.x(), diff.y(), 0, relative='view')
                else:
                    self.orbit(-diff.x(), diff.y())
            elif ev.buttons() == QtCore.Qt.MouseButton.MiddleButton:
                if (ev.modifiers() & QtCore.Qt.KeyboardModifier.ControlModifier):
                    self.pan(diff.x(), 0, diff.y(), relative='view-upright')
                else:
                    self.pan(diff.x(), diff.y(), 0, relative='view-upright')

        def mouseReleaseEvent(self, ev):
            pass

        def wheelEvent(self, ev):
            delta = ev.angleDelta().x()
            if delta == 0:
                delta = ev.angleDelta().y()
            if (ev.modifiers() & QtCore.Qt.KeyboardModifier.ControlModifier):
                self.opts['fov'] *= 0.999**delta
            else:
                self.opts['distance'] *= 0.999**delta
            self.update()

        def keyPressEvent(self, ev):
            if ev.key() in self.noRepeatKeys:
                ev.accept()
                if ev.isAutoRepeat():
                    return
                self.keysPressed[ev.key()] = 1
                self.evalKeyState()

        def keyReleaseEvent(self, ev):
            if ev.key() in self.noRepeatKeys:
                ev.accept()
                if ev.isAutoRepeat():
                    return
                try:
                    del self.keysPressed[ev.key()]
                except KeyError:
                    self.keysPressed = {}
                self.evalKeyState()

        def evalKeyState(self):
            speed = 2.0
            if len(self.keysPressed) > 0:
                for key in self.keysPressed:
                    if key == QtCore.Qt.Key.Key_Right:
                        self.orbit(azim=-speed, elev=0)
                    elif key == QtCore.Qt.Key.Key_Left:
                        self.orbit(azim=speed, elev=0)
                    elif key == QtCore.Qt.Key.Key_Up:
                        self.orbit(azim=0, elev=-speed)
                    elif key == QtCore.Qt.Key.Key_Down:
                        self.orbit(azim=0, elev=speed)
                    elif key == QtCore.Qt.Key.Key_PageUp:
                        pass
                    elif key == QtCore.Qt.Key.Key_PageDown:
                        pass
                    self.keyTimer.start(16)
            else:
                self.keyTimer.stop()

        def readQImage(self):
            """
            Read the current buffer pixels out as a QImage.
            """
            return self.grabFramebuffer()

        def renderToArray(self, size, format=GL.GL_BGRA, type=GL.GL_UNSIGNED_BYTE, textureSize=1024, padding=256):
            w,h = map(int, size)

            self.makeCurrent()

            texwidth = textureSize

            fbo = QtOpenGL.QOpenGLFramebufferObject(texwidth, texwidth,
                        QtOpenGL.QOpenGLFramebufferObject.Attachment.CombinedDepthStencil,
                        GL.GL_TEXTURE_2D)

            output = np.empty((h, w, 4), dtype=np.ubyte)
            data = np.empty((texwidth, texwidth, 4), dtype=np.ubyte)

            try:
                p2 = 2 * padding
                for x in range(-padding, w-padding, texwidth-p2):
                    for y in range(-padding, h-padding, texwidth-p2):
                        x2 = min(x+texwidth, w+padding)
                        y2 = min(y+texwidth, h+padding)
                        w2 = x2-x
                        h2 = y2-y

                        fbo.bind()
                        GL.glViewport(0, 0, w2, h2)
                        self.paint(region=(x, h-y-h2, w2, h2), viewport=(0, 0, w, h))  # only render sub-region

                        fbo.bind()
                        GL.glReadPixels(0, 0, texwidth, texwidth, format, type, data)
                        data_yflip = data[::-1, ...]
                        output[y+padding:y2-padding, x+padding:x2-padding] = data_yflip[-(h2-padding):-padding, padding:w2-padding]

            finally:
                fbo.release()

            return output

    class GLViewWidget(GLViewMixin, QtWidgets.QOpenGLWidget):

        def __init__(self, *args, devicePixelRatio=None, **kwargs):
            """
            Basic widget for displaying 3D data
              - Rotation/scale controls
              - Axis/grid display
              - Export options

            ================ ==============================================================
            **Arguments:**
            parent           (QObject, optional): Parent QObject. Defaults to None.
            devicePixelRatio No longer in use. High-DPI displays should automatically
                             detect the correct resolution.
            rotationMethod   (str): Mechanism to drive the rotation method, options are
                             'euler' and 'quaternion'. Defaults to 'euler'.
            ================ ==============================================================
            """
            super().__init__(*args, **kwargs)
            self.setFocusPolicy(QtCore.Qt.FocusPolicy.ClickFocus)