Cubo_2.c

// DIBUJO DE UN CUBO CARA POR CARA CON DIFERENTES PERSPECTIVAS

#include <GL/glut.h>

GLfloat anguloCuboX = 0.0f; //angulos del cubo
GLfloat anguloCuboY = 0.0f;

int hazPerspectiva = 0;

void reshape(int width, int height)
{
    glViewport(0, 0, width, height);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    
    if(hazPerspectiva)
	gluPerspective(60.0f, (GLfloat)width/(GLfloat)height, 1.0f, 20.0f);
    else
	glOrtho(-4, 4, -4, 4, 1, 10);

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

}

void drawCube(void)
{
    glColor3f(1.0f, 0.0f, 0.0f);
    glBegin(GL_QUADS);  //cara frontal
    glVertex3f(-1.0f, -1.0f,  1.0f);
    glVertex3f( 1.0f, -1.0f,  1.0f);
    glVertex3f( 1.0f,  1.0f,  1.0f);
    glVertex3f(-1.0f,  1.0f,  1.0f);
    glEnd();

    glColor3f(0.0f, 1.0f, 0.0f);
    glBegin(GL_QUADS);  //cara trasera
    glVertex3f( 1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f,  1.0f, -1.0f);
    glVertex3f( 1.0f,  1.0f, -1.0f);
    glEnd();

    glColor3f(0.0f, 0.0f, 1.0f);
    glBegin(GL_QUADS);  //cara lateral izq
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glVertex3f(-1.0f, -1.0f,  1.0f);
    glVertex3f(-1.0f,  1.0f,  1.0f);
    glVertex3f(-1.0f,  1.0f, -1.0f);
    glEnd();

    glColor3f(1.0f, 1.0f, 0.0f);
    glBegin(GL_QUADS);  //cara lateral dcha
    glVertex3f( 1.0f, -1.0f,  1.0f);
    glVertex3f( 1.0f, -1.0f, -1.0f);
    glVertex3f( 1.0f,  1.0f, -1.0f);
    glVertex3f( 1.0f,  1.0f,  1.0f);
    glEnd();

    glColor3f(0.0f, 1.0f, 1.0f);
    glBegin(GL_QUADS);  //cara arriba
    glVertex3f(-1.0f,  1.0f,  1.0f);
    glVertex3f( 1.0f,  1.0f,  1.0f);
    glVertex3f( 1.0f,  1.0f, -1.0f);
    glVertex3f(-1.0f,  1.0f, -1.0f);
    glEnd();

    glColor3f(1.0f, 0.0f, 1.0f);
    glBegin(GL_QUADS);  //cara abajo
    glVertex3f( 1.0f, -1.0f, -1.0f);
    glVertex3f( 1.0f, -1.0f,  1.0f);
    glVertex3f(-1.0f, -1.0f,  1.0f);
    glVertex3f(-1.0f, -1.0f, -1.0f);
    glEnd();

}

void display()
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glLoadIdentity();

    glTranslatef(0.0f, 0.0f, -5.0f);

    glRotatef(anguloCuboX, 1.0f, 0.0f, 0.0f);
    glRotatef(anguloCuboY, 0.0f, 1.0f, 0.0f);

    drawCube();

    glLoadIdentity();

    glFlush();
    glutSwapBuffers();

    anguloCuboX+=0.1f;
    anguloCuboY+=0.1f;

}

void init()
{
    glClearColor(0,0,0,0);

    glEnable(GL_DEPTH_TEST);
}

void idle()
{
    display();
}

void keyboard(unsigned char key, int x, int y)
{
    switch(key)
    {
    case 'p':
    case 'P':
	hazPerspectiva=1;
	reshape(400,400);
	break;

    case 'o':
    case 'O':
	hazPerspectiva=0;
	reshape(400,400);
	break;

    case 27:   // escape
	exit(0);
        break;

    }
}

int main(int argc, char **argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
    glutInitWindowPosition(100, 100);
    glutInitWindowSize(400, 400);
    glutCreateWindow("Cubo");
    init();
    glutDisplayFunc(display);
    glutReshapeFunc(reshape);
    glutIdleFunc(idle);
    glutKeyboardFunc(keyboard);
    glutMainLoop();
    return 0;
}