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

viewDistance = 15.0
viewRotY = 0.0
viewRotX = 0.0
cameraVelX = 0.0
cameraVelY = 0.0
prevTime = time.time()

textureID = 0


def createTextureData(width,height):
    textureData = [ ]
    for i in range(0,height):
        for j in range(0,width):
            x = float(j) / width * math.pi
            y = float(i) / height * math.pi
            rgb = [ math.fabs(math.sin(x)*math.sin(y)), 
                    math.fabs(math.cos(x)*math.sin(y)),
                    0]
            rgb[0] = int(rgb[0] * 255)
            rgb[1] = int(rgb[1] * 255)
            rgb[2] = int(rgb[2] * 255)
            textureData.append(rgb)
    return textureData


def createTextureString(rgbList):
    s = ''
    for rgb in rgbList:
        s += struct.pack('BBB', rgb[0], rgb[1], rgb[2])
    return s


def initTexture():
    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_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    width = 32
    height = 32
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height,
                 0, GL_RGB, GL_UNSIGNED_BYTE,
                 createTextureString(createTextureData(width,height)))
    glBindTexture(GL_TEXTURE_2D, 0)


def draw():
    glClearColor(0, 0.3, 0.5, 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)

    glEnable(GL_TEXTURE_2D)
    glBindTexture(GL_TEXTURE_2D, textureID)

    glBegin(GL_QUADS)

    glTexCoord2f(0, 0)
    glVertex3f(-5, -5, 0)

    glTexCoord2f(1, 0)
    glVertex3f(5, -5, 0)

    glTexCoord2f(1, 1)
    glVertex3f(5, 5, 0)

    glTexCoord2f(0, 1)
    glVertex3f(-5, 5, 0)

    glEnd()

    glDisable(GL_TEXTURE_2D)
    
    glutSwapBuffers()


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(400,400)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutSpecialFunc(specialkey)
glutSpecialUpFunc(specialkeyUp)
glutIgnoreKeyRepeat(1)
glutIdleFunc(update)
glEnable(GL_DEPTH_TEST)
initTexture()
glutMainLoop()