/* 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
*/

#include <math.h>
#include <stdio.h>
#include <tw.h>

bool BW = true;                // which flag to show

void toggleFlag(unsigned char key, int x, int y) {
    BW = !BW;
    glutPostRedisplay();
}

/* ================================================================
   Texture arrays
*/

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

const int BWwidth = 4;
const int BWheight = 4;

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

GLubyte bwTexture[BWwidth][BWheight] = {
    {   0,   0,   0, 255 },
    {   0,   0, 255,   0 },
    { 255,   0, 255, 255 },
    {   0, 255, 255, 255 }
};

// The dimensions of the color texture array.  

const int ColorWidth = 2;
const int 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.

GLubyte colorTexture[2][2][4] = {
    { {0,0,0,255}, {255,0,0,255} },
    { {0,255,0,255}, {0,0,255,255} }
};
    
/* ================================================================ */

void 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);

    glPixelStorei(GL_UNPACK_ALIGNMENT,1);
    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);
    }
    twError();

    glEnable(GL_TEXTURE_2D);

    glutSolidTeapot(1);

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

/* ================================================================ */
int main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    twInitWindowSize(500, 500);
    glutCreateWindow(argv[0]);
    glutDisplayFunc(display);
    twBoundingBox(0,10,0,5,-1,1);
    twMainInit();
    twKeyCallback('u',toggleFlag,"toggle which flag to show");
    glutMainLoop();                   
}