# -*- coding: utf-8 -*-
"""
Demonstrate use of GLLinePlotItem to draw cross-sections of a surface.

"""
## Add path to library (just for examples; you do not need this)
import initExample

from pyqtgraph.Qt import QtCore, QtGui
import pyqtgraph.opengl as gl
import pyqtgraph as pg
import numpy as np

app = QtGui.QApplication([])
w = gl.GLViewWidget()
w.opts['distance'] = 40
w.show()
w.setWindowTitle('pyqtgraph example: GLLinePlotItem')

gx = gl.GLGridItem()
gx.rotate(90, 0, 1, 0)
gx.translate(-10, 0, 0)
w.addItem(gx)
gy = gl.GLGridItem()
gy.rotate(90, 1, 0, 0)
gy.translate(0, -10, 0)
w.addItem(gy)
gz = gl.GLGridItem()
gz.translate(0, 0, -10)
w.addItem(gz)

def fn(x, y):
    return np.cos((x**2 + y**2)**0.5)

n = 51
y = np.linspace(-10,10,n)
x = np.linspace(-10,10,100)
for i in range(n):
    yi = np.array([y[i]]*100)
    d = (x**2 + yi**2)**0.5
    z = 10 * np.cos(d) / (d+1)
    pts = np.vstack([x,yi,z]).transpose()
    plt = gl.GLLinePlotItem(pos=pts, color=pg.glColor((i,n*1.3)))
    w.addItem(plt)
    


## Start Qt event loop unless running in interactive mode.
if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()