''' Simplest demo of texture mapping using static arrays instead
files.  There are two arrays, one black&white and one color.  Toggle
between them with the 'u' callback.

Scott D. Anderson
Fall 2004
Ported to Python Fall 2009
'''

import sys
import math                            # for sin and cos

try:
  from TW import *
except:
  print '''
ERROR: Couldn't import TW.
        '''
## ================================================================

BW = True                       # which flag to show

def toggleFlag(key, x, y):
    global BW
    BW =  not BW;
    glutPostRedisplay();

ShowTeapot = False

def toggleObject(key, x, y):
    global ShowTeapot
    ShowTeapot =  not ShowTeapot;
    glutPostRedisplay();

### ================================================================
###   Texture arrays

## The dimensions of the black and white texture array.  Note that they
## are both powers of 2.

BWwidth = 4
BWheight = 4

## The array elements are unsigned bytes:  grayscale values from 0 to 255.

bwTexture = ((  0,   0,   0, 255),
             (  0,   0, 255,   0),
             (255,   0, 255, 255),
             (  0, 255, 255, 255))

## The dimensions of the color texture array.  

ColorWidth = 2
ColorHeight = 2

## We add a extra value to handle the issue of rows being aligned on a
## four-byte boundary.  By using RGBA instead of RGB, the rows necessarily
## are aligned on a four-byte boundary, since each element is 4 bytes.

colorTexture = (
    ( (0,0,0,255), (255,0,0,255) ),
    ( (0,255,0,255), (0,0,255,255) )
    )
    
### ================================================================

def display():
    twDisplayInit();
    twCamera();

    glPushAttrib(GL_ALL_ATTRIB_BITS);

    glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    if BW:
        glTexImage2D(GL_TEXTURE_2D, 0, 3, BWwidth, BWheight, 0,
                     GL_LUMINANCE, GL_UNSIGNED_BYTE, bwTexture);
    else:
        glTexImage2D(GL_TEXTURE_2D, 0, 3, ColorWidth, ColorHeight, 0,
                     GL_RGBA, GL_UNSIGNED_BYTE, colorTexture);

    glEnable(GL_TEXTURE_2D);

    if ShowTeapot:
        glPushMatrix()
        glScale(5,5,5)
        glutSolidTeapot()
        glPopMatrix()
    else:
        glBegin(GL_QUADS);
        glTexCoord2f(0,1); glVertex3f( 0,0,0); # green
        glTexCoord2f(1,1); glVertex3f(10,0,0); # blue
        glTexCoord2f(1,0); glVertex3f(10,5,0); # red 
        glTexCoord2f(0,0); glVertex3f( 0,5,0); # black
        glEnd();

    glPopAttrib();
    glFlush();
    glutSwapBuffers();

def main():
    glutInit(sys.argv)
    glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH)
    twBoundingBox(0,10,0,5,-1,1);
    twInitWindowSize(500,500)
    glutCreateWindow(sys.argv[0])
    glutDisplayFunc(display)
    twMainInit()
    twKeyCallback('u',toggleFlag,"toggle which flag to show");
    twKeyCallback('t',toggleObject,"toggle whether to show Quad or Teapot");
    glutMainLoop()

if __name__ == '__main__':
  main()