#!/bin/env python
#   Rotating cube with color interpolation 

#   Demonstration of use of homogeneous coordinate 
#   transformations and simple data structure for representing
#   cube from Chapter 4 

#  Both normals and colors are assigned to the vertices 
#  Cube is centered at origin so (unnormalized) normals
#  are the same as the vertex values 

#  This version has been hacked up to illustrate:
#  -- Two rotating cubes, both displaced from the origin.
#  -- Axes, for orientation purposes
#  -- Perspective projection (instead of orthographic) 
#  -- Keyboard interaction (moving the eye x-coordinate with
#     the arrow keys), 'q' to quit).
#

from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
import sys

vertices = [[-1.0,-1.0,-1.0],[1.0,-1.0,-1.0],
	[1.0,1.0,-1.0], [-1.0,1.0,-1.0], [-1.0,-1.0,1.0], 
	[1.0,-1.0,1.0], [1.0,1.0,1.0], [-1.0,1.0,1.0]]

normals = [[-1.0,-1.0,-1.0],[1.0,-1.0,-1.0],
	[1.0,1.0,-1.0], [-1.0,1.0,-1.0], [-1.0,-1.0,1.0], 
	[1.0,-1.0,1.0], [1.0,1.0,1.0], [-1.0,1.0,1.0]]

colors = [[0.0,0.0,0.0],[1.0,0.0,0.0],
	[1.0,1.0,0.0], [0.0,1.0,0.0], [0.0,0.0,1.0], 
	[1.0,0.0,1.0], [1.0,1.0,1.0], [0.0,1.0,1.0]];

theta = [0.0, 0.0, 0.0]
axis = 2
eyex = 3.0
eyey = 3.0
eyez = 7.0

#   draw a polygon via list of vertices 
def polygon(*vert_numbs):
    glBegin(GL_POLYGON)
    for vert_num in vert_numbs:
       glColor3fv(colors[vert_num])
       glNormal3fv(normals[vert_num])
       glVertex3fv(vertices[vert_num])
    glEnd()

#   draw the six faces of the cube as six polygons
def colorcube():
    polygon(0,3,2,1)
    polygon(2,3,7,6)
    polygon(0,4,7,3)
    polygon(1,2,6,5)
    polygon(4,5,6,7)
    polygon(0,1,5,4)

#   Draw one axis:
#     axno  0=x, 1=y, 2=z
#     leng  length from origin to each end of axis
#
def draw_axis(axno, leng):

    # Set color
    colors = [0.0, 0.0, 0.0]
    colors[axno] = 1.0
    glColor3fv(colors)

    # Draw line
    endpt = [0.0, 0.0, 0.0]
    glBegin(GL_LINE)
    endpt[axno] = -leng
    glVertex3fv(endpt)
    endpt[axno] = leng
    glVertex3fv(endpt)
    glEnd()

    glPointSize(4.0)
    glBegin(GL_POINTS)
    glColor3f(1.0, 1.0, 1.0)
    for x in range(-int(leng), int(leng)+1):
        pt = [0.0, 0.0, 0.0]
        pt[axno] = x
        glVertex3fv(pt)
    glEnd()

def axes():
    draw_axis(0, 2.0)
    draw_axis(1, 2.0)
    draw_axis(2, 2.0)


#   display callback, clear frame buffer and z buffer,
#   rotate cube and draw, swap buffers 
def display():
    global eyex, eyey, eyez
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)

    glLoadIdentity()
    gluLookAt(eyex, eyey, eyez,  0.0, 0.0, 0.0,  0.0, 1.0, 0.0)
    axes()

    # Move the first cube up and to the right
    glPushMatrix()
    glTranslatef(1.1, 1.1, 0.0)

    # Rotate and draw first cube
    glRotatef(theta[0], 1.0, 0.0, 0.0)
    glRotatef(theta[1], 0.0, 1.0, 0.0)
    glRotatef(theta[2], 0.0, 0.0, 1.0)
    colorcube()

    glPopMatrix()

    # Move the second cube down and to the left 
    glPushMatrix()
    glTranslatef(-1.1, -1.1, 0.0)

    # Rotate and draw second cube
    glRotatef(theta[0], 1.0, 0.0, 0.0)
    glRotatef(theta[1], 0.0, 1.0, 0.0)
    glRotatef(theta[2], 0.0, 0.0, 1.0)
    colorcube()
    glPopMatrix()
    glFlush()
    glutSwapBuffers()

#   Idle callback, spin cube 1 degrees about selected axis 
def spinCube():
    global theta
    theta[axis] += 1.0
    if theta[axis] >= 360: theta[axis] -= 360
    glutPostRedisplay()

#   mouse callback, selects an axis about which to rotate 
def mouse(btn, state, x, y):
    global axis
    if btn==GLUT_LEFT_BUTTON and state == GLUT_DOWN: axis = 0
    if btn==GLUT_MIDDLE_BUTTON and state == GLUT_DOWN: axis = 1
    if btn==GLUT_RIGHT_BUTTON and state == GLUT_DOWN: axis = 2

#   Special key callback
def specialkey(keypressed, x, y):
    global eyex, eyey, eyez

    if keypressed == GLUT_KEY_LEFT:
        eyex -= 0.5
    elif keypressed == GLUT_KEY_RIGHT:
        eyex += 0.5

#   Regular key callback
def key(keypressed, x, y):
    if keypressed == 'q' or keypressed == 'Q':
        sys.exit()
    
def myReshape(w, h):
    dim = min(w, h) 
    glViewport(0, 0, dim, dim)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    #glOrtho(-4.0, 4.0,  -4.0, 4.0,  -10.0, 10.0)
    glFrustum(-4.0, 4.0, -4.0, 4.0, 5.0, 15.0)
    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity()

if __name__ == "__main__":
    glutInit(sys.argv)

#   need both double buffering and z buffer 

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
    glutInitWindowSize(500, 500)
    glutCreateWindow("colorcube")
    glutReshapeFunc(myReshape)
    glutDisplayFunc(display)
    glutIdleFunc(spinCube)
    glutMouseFunc(mouse)
    glutSpecialFunc(specialkey)
    glutKeyboardFunc(key)
    glEnable(GL_DEPTH_TEST) #   Enable hidden--surface--removal 
    glutMainLoop()