/*
 * CPSC  465
 * Principles of Computer Graphics
 * Section 1
 * Spring 2006
 *
 * Texture Mapping Demonstration
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <GL/glut.h>

unsigned char texture[16][16][3];

void display(void)
{
    float lightpos[] = { 2.0, 2.0, 2.0, 1.0 };

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    gluLookAt(0.0, 0.0, 2.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);

    glLightfv(GL_LIGHT0, GL_POSITION, lightpos);

    glRotated(45.0, 1.0, 1.0, 0.0);

    glColor3f(1.0, 1.0, 1.0);
    glBegin(GL_QUADS);
    glNormal3d(0.0, 0.0, 1.0);
    glTexCoord2d(1.0, 1.0);
    glVertex3d(0.5, -0.5, 0.5);
    glTexCoord2d(1.0, 0.0);
    glVertex3d(0.5, 0.5, 0.5);
    glTexCoord2d(0.0, 0.0);
    glVertex3d(-0.5, 0.5, 0.5);
    glTexCoord2d(0.0, 1.0);
    glVertex3d(-0.5, -0.5, 0.5);
    glEnd();

    glBegin(GL_QUADS);
    glNormal3d(0.0, 1.0, 0.0);
    glTexCoord2d(0.0, 1.0);
    glVertex3d(-0.5, 0.5, -0.5);
    glTexCoord2d(0.0, 0.0);
    glVertex3d(-0.5, 0.5, 0.5);
    glTexCoord2d(1.0, 0.0);
    glVertex3d(0.5, 0.5, 0.5);
    glTexCoord2d(1.0, 1.0);
    glVertex3d(0.5, 0.5, -0.5);
    glEnd();

    glBegin(GL_QUADS);
    glNormal3d(-1.0, 0.0, 0.0);
    glTexCoord2d(0.0, 0.0);
    glVertex3d(-0.5, -0.5, -0.5);
    glTexCoord2d(0.0, 1.0);
    glVertex3d(-0.5, -0.5, 0.5);
    glTexCoord2d(1.0, 1.0);
    glVertex3d(-0.5, 0.5, 0.5);
    glTexCoord2d(1.0, 0.0);
    glVertex3d(-0.5, 0.5, -0.5);
    glEnd();

    glutSwapBuffers();
}

void reshape(int w, int h)
{
    double scaledWidth, scaledHeight;

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    /* a square window would be exactly 2.0 by 2.0) */
    if (w > h) {
        scaledWidth = 2.0 * w / h;
        scaledHeight = 2.0;
    } else {
        scaledWidth = 2.0;
        scaledHeight = 2.0 * h / w;
    }

    glFrustum(-scaledWidth / 2.0, scaledWidth / 2.0,
              -scaledHeight / 2.0, scaledHeight / 2.0, 1.0, 6.0);

    glViewport(0, 0, w, h);
}

void mouse(int button, int state, int x, int y)
{
    static int mapping = 0;

    if (button != GLUT_LEFT_BUTTON || state != GLUT_DOWN)
        return;

    mapping = !mapping;
    if (mapping) {
        glEnable(GL_TEXTURE_2D);

    } else {
        glDisable(GL_TEXTURE_2D);
    }

    glutPostRedisplay();
}

int main(int argc, char *argv[])
{
    int i, j;

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutCreateWindow("Texture Mapping Demonstration");
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutMouseFunc(mouse);

    glEnable(GL_DEPTH_TEST);
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);
    glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);
    glEnable(GL_COLOR_MATERIAL);

    glClearColor(0.0, 0.0, 0.0, 1.0);

    for (i = 0; i < 16; i++) {
        for (j = 0; j < 16; j++) {
            texture[i][j][0] = ((i + j) % 2 == 0) ? 255 : 0;
            texture[i][j][1] = ((i + j) % 2 == 0) ? 255 : 0;
            texture[i][j][2] = ((i + j) % 2 == 0) ? 0 : 255;
        }
    }

    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, 16, 16, 0, GL_RGB,
                 GL_UNSIGNED_BYTE, texture);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);

    glutMainLoop();
    return 0;
}