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"""
Navigation paradigm in PyOpenGL

Needs to have PyOpenGl e.g., pip install pyopengl.
It draws a scene for navigation paradigm to test
if it is possible to transfer it to MALTAB with
Psychtoolbox installed.

Michael Tesar 2017
Ceske Budejovice
"""
from OpenGL.GLUT import *
from OpenGL.GLU import *
from OpenGL.GL import *
import sys

name = 'Navigation paradigm'


def main():
    """
    Main function which handles scene and also
    OpenGL (PyOpenGl) basic functions as drawing
    of screen, enabling shader and light etc.
    :return: void
    """
    glutInit(sys.argv)
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
    glutInitWindowSize(800, 800)
    glutInitWindowPosition(350, 200)
    glutCreateWindow(name)

    glClearColor(0., 0., 0., 1.)
    glShadeModel(GL_SMOOTH)
    glEnable(GL_CULL_FACE)
    glEnable(GL_DEPTH_TEST)
    glEnable(GL_LIGHTING)
    lightZeroPosition = [10., 4., 10., 1.]
    lightZeroColor = [0.8, 1.0, 0.8, 1.0]
    glLightfv(GL_LIGHT0, GL_POSITION, lightZeroPosition)
    glLightfv(GL_LIGHT0, GL_DIFFUSE, lightZeroColor)
    glLightf(GL_LIGHT0, GL_CONSTANT_ATTENUATION, 0.1)
    glLightf(GL_LIGHT0, GL_LINEAR_ATTENUATION, 0.05)
    glEnable(GL_LIGHT0)
    glutDisplayFunc(displayscene)
    glMatrixMode(GL_PROJECTION)
    gluPerspective(40., 1., 1., 40.)
    glMatrixMode(GL_MODELVIEW)
    gluLookAt(0, 0, 10,
              0, 0, 0,
              0, 1, 0)
    glPushMatrix()
    glutMainLoop()
    return


def displayscene():
    """
    Draws two spheres and arena with
    basic texture on it.
    :return: void
    """
    glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT)
    glPushMatrix()

    # Left sphere
    color = [1.0, 0.0, 0.0, 1.0]
    glMaterialfv(GL_FRONT, GL_DIFFUSE, color)
    glTranslatef(-2, 0, 0)
    glutSolidSphere(1, 100, 20)

    # Right sphere
    color = [0.0, 1.0, 0.0, 1.0]
    glMaterialfv(GL_FRONT, GL_DIFFUSE, color)
    glTranslatef(4, 0, 0)
    glutSolidSphere(1, 100, 20)

    glPopMatrix()
    glutSwapBuffers()
    return


def loadtexture():
    """
    Defines a global texture for applying
    in any time as fucntion
    :return:
    """
    image = open("brick.jpg")

    ix = image.size[0]
    iy = image.size[1]
    image = image.tostring("raw", "RGBX", 0, -1)

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1)
    glTexImage2D(GL_TEXTURE_2D, 0, 3, ix, iy, 0, GL_RGBA, GL_UNSIGNED_BYTE, image)
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP)
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP)
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT)
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT)
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)
    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)
    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL)
    return image

if __name__ == '__main__':
    main()