# Source code for pyqtgraph.opengl.items.GLGridItem

    import numpy as np

    from OpenGL.GL import *
    from .. GLGraphicsItem import GLGraphicsItem
    from ... import QtGui

    __all__ = ['GLGridItem']

    class GLGridItem(GLGraphicsItem):
        """
        **Bases:** :class:`GLGraphicsItem <pyqtgraph.opengl.GLGraphicsItem>`

        Displays a wire-grame grid.
        """

        def __init__(self, size=None, color=None, antialias=True, glOptions='translucent'):
            GLGraphicsItem.__init__(self)
            self.setGLOptions(glOptions)
            self.antialias = antialias
            if size is None:
                size = QtGui.QVector3D(20,20,1)
            self.setSize(size=size)
            self.setSpacing(1, 1, 1)

        def setSize(self, x=None, y=None, z=None, size=None):
            """
            Set the size of the axes (in its local coordinate system; this does not affect the transform)
            Arguments can be x,y,z or size=QVector3D().
            """
            if size is not None:
                x = size.x()
                y = size.y()
                z = size.z()
            self.__size = [x,y,z]
            self.update()

        def size(self):
            return self.__size[:]

        def setSpacing(self, x=None, y=None, z=None, spacing=None):
            """
            Set the spacing between grid lines.
            Arguments can be x,y,z or spacing=QVector3D().
            """
            if spacing is not None:
                x = spacing.x()
                y = spacing.y()
                z = spacing.z()
            self.__spacing = [x,y,z]
            self.update()

        def spacing(self):
            return self.__spacing[:]

        def paint(self):
            self.setupGLState()

            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)

            glBegin( GL_LINES )

            x,y,z = self.size()
            xs,ys,zs = self.spacing()
            xvals = np.arange(-x/2., x/2. + xs*0.001, xs)
            yvals = np.arange(-y/2., y/2. + ys*0.001, ys)
            glColor4f(1, 1, 1, .3)
            for x in xvals:
                glVertex3f(x, yvals[0], 0)
                glVertex3f(x,  yvals[-1], 0)
            for y in yvals:
                glVertex3f(xvals[0], y, 0)
                glVertex3f(xvals[-1], y, 0)

            glEnd()