import sys, time, math, Image
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *

viewDistance = 12.0
viewRotY = 0.0
viewRotX = 0.0
cameraVelX = 0.0
cameraVelY = 0.0
prevTime = time.time()


def draw():
    glClearColor(0.5, 0.7, 1, 0)
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    gluPerspective(50.0, 1.0, 1.0, 100.0)
    glMatrixMode(GL_MODELVIEW)

    glLoadIdentity()
    glTranslatef(0.0, 0.0, -viewDistance)
    glRotatef(viewRotX, 1.0, 0.0, 0.0)
    glRotatef(viewRotY, 0.0, 1.0, 0.0)
    
    glColor4f(0.1, 1, 0.2, 1)
    glBegin(GL_QUADS)
    glVertex3f(-20, -3, -20)
    glVertex3f(20, -3, -20)
    glVertex3f(20, -3, 20)
    glVertex3f(-20, -3, 20)
    glEnd()

    glEnable(GL_ALPHA_TEST)
    glAlphaFunc(GL_GREATER, 0.25)
   
    for pos in [ [0,-8], [-2,-4], [3,0] ]:
        glPushMatrix()
        glTranslatef(pos[0], -3, pos[1])
        drawTree()
        glPopMatrix()
   
    glDisable(GL_ALPHA_TEST)

    glutSwapBuffers()


textureID = 0

def drawTree():
    glEnable(GL_TEXTURE_2D)
    glBindTexture(GL_TEXTURE_2D, textureID)
    glColor4f(1,1,1,1)
    glBegin(GL_QUADS)
    glTexCoord2f(0,0)
    glVertex3f(-3, 0, 0)
    glTexCoord2f(1,0)
    glVertex3f(3, 0, 0)
    glTexCoord2f(1,1)
    glVertex3f(3, 8, 0)
    glTexCoord2f(0,1)
    glVertex3f(-3, 8, 0)
    glEnd()
    glBindTexture(GL_TEXTURE_2D, 0)
    glDisable(GL_TEXTURE_2D)


import os
startDir = os.getcwd() + os.sep

def initTexture(filename):
    img = Image.open(startDir + filename)
    img = img.transpose(Image.FLIP_TOP_BOTTOM)
    global textureID
    textureID = glGenTextures(1)
    glBindTexture(GL_TEXTURE_2D, textureID)
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, img.size[0], img.size[1],
                 0, GL_RGBA, GL_UNSIGNED_BYTE, img.tostring())
    glBindTexture(GL_TEXTURE_2D, 0)


def keyboard(key, x, y):
    global viewDistance
    if key == chr(27):
        sys.exit(0)
    elif key == '.':
        viewDistance -= 1
    elif key == ',':
        viewDistance += 1

def specialkey(key,x,y):
    global cameraVelX, cameraVelY
    if key == GLUT_KEY_LEFT:
        cameraVelY += 90
    elif key == GLUT_KEY_RIGHT:
        cameraVelY -= 90
    elif key == GLUT_KEY_UP:
        cameraVelX += 90
    elif key == GLUT_KEY_DOWN:
        cameraVelX -= 90

def specialkeyUp(key,x,y):
    global cameraVelX, cameraVelY
    if key == GLUT_KEY_LEFT:
        cameraVelY -= 90
    elif key == GLUT_KEY_RIGHT:
        cameraVelY += 90
    elif key == GLUT_KEY_UP:
        cameraVelX -= 90
    elif key == GLUT_KEY_DOWN:
        cameraVelX += 90

def update():
    global viewRotX, viewRotY, cameraVelX, cameraVelY
    global prevTime
    t = time.time()
    dt = t - prevTime
    prevTime = t
    viewRotX += cameraVelX * dt
    viewRotY += cameraVelY * dt
    glutPostRedisplay()

glutInit([])
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH)
glutInitWindowSize(500,500)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutSpecialFunc(specialkey)
glutSpecialUpFunc(specialkeyUp)
glutIgnoreKeyRepeat(1)
glutIdleFunc(update)
glEnable(GL_DEPTH_TEST)
initTexture("tree.tiff")
glutMainLoop()