# Source code for pyqtgraph.opengl.items.GLLinePlotItem

    from OpenGL.GL import *
    from OpenGL.arrays import vbo
    from .. GLGraphicsItem import GLGraphicsItem
    from .. import shaders
    from ... import QtGui
    import numpy as np

    __all__ = ['GLLinePlotItem']

    class GLLinePlotItem(GLGraphicsItem):
        """Draws line plots in 3D."""

        def __init__(self, **kwds):
            """All keyword arguments are passed to setData()"""
            GLGraphicsItem.__init__(self)
            glopts = kwds.pop('glOptions', 'additive')
            self.setGLOptions(glopts)
            self.pos = None
            self.mode = 'line_strip'
            self.width = 1.
            self.color = (1.0,1.0,1.0,1.0)
            self.setData(**kwds)

        def setData(self, **kwds):
            """
            Update the data displayed by this item. All arguments are optional;
            for example it is allowed to update vertex positions while leaving
            colors unchanged, etc.

            ====================  ==================================================
            **Arguments:**
            ------------------------------------------------------------------------
            pos                   (N,3) array of floats specifying point locations.
            color                 (N,4) array of floats (0.0-1.0) or
                                  tuple of floats specifying
                                  a single color for the entire item.
            width                 float specifying line width
            antialias             enables smooth line drawing
            mode                  'lines': Each pair of vertexes draws a single line
                                           segment.
                                  'line_strip': All vertexes are drawn as a
                                                continuous set of line segments.
            ====================  ==================================================
            """
            args = ['pos', 'color', 'width', 'mode', 'antialias']
            for k in kwds.keys():
                if k not in args:
                    raise Exception('Invalid keyword argument: %s (allowed arguments are %s)' % (k, str(args)))
            self.antialias = False
            for arg in args:
                if arg in kwds:
                    setattr(self, arg, kwds[arg])
                    #self.vbo.pop(arg, None)
            self.update()

        def initializeGL(self):
            pass

        #def setupGLState(self):
            #"""Prepare OpenGL state for drawing. This function is called immediately before painting."""
            ##glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)  ## requires z-sorting to render properly.
            #glBlendFunc(GL_SRC_ALPHA, GL_ONE)
            #glEnable( GL_BLEND )
            #glEnable( GL_ALPHA_TEST )
            #glDisable( GL_DEPTH_TEST )

            ##glEnable( GL_POINT_SMOOTH )

            ##glHint(GL_POINT_SMOOTH_HINT, GL_NICEST)
            ##glPointParameterfv(GL_POINT_DISTANCE_ATTENUATION, (0, 0, -1e-3))
            ##glPointParameterfv(GL_POINT_SIZE_MAX, (65500,))
            ##glPointParameterfv(GL_POINT_SIZE_MIN, (0,))

        def paint(self):
            if self.pos is None:
                return
            self.setupGLState()

            glEnableClientState(GL_VERTEX_ARRAY)

            try:
                glVertexPointerf(self.pos)

                if isinstance(self.color, np.ndarray):
                    glEnableClientState(GL_COLOR_ARRAY)
                    glColorPointerf(self.color)
                else:
                    if isinstance(self.color, QtGui.QColor):
                        glColor4f(*fn.glColor(self.color))
                    else:
                        glColor4f(*self.color)
                glLineWidth(self.width)
                #glPointSize(self.width)

                if self.antialias:
                    glEnable(GL_LINE_SMOOTH)
                    glEnable(GL_BLEND)
                    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
                    glHint(GL_LINE_SMOOTH_HINT, GL_NICEST)

                if self.mode == 'line_strip':
                    glDrawArrays(GL_LINE_STRIP, 0, int(self.pos.size / self.pos.shape[-1]))
                elif self.mode == 'lines':
                    glDrawArrays(GL_LINES, 0, int(self.pos.size / self.pos.shape[-1]))
                else:
                    raise Exception("Unknown line mode '%s'. (must be 'lines' or 'line_strip')" % self.mode)

            finally:
                glDisableClientState(GL_COLOR_ARRAY)
                glDisableClientState(GL_VERTEX_ARRAY)