/* Rotating cube with color interpolation */

/* Demonstration of use of homogeneous coordinate 
transformations and simple data structure for representing
cube from Chapter 4 */

/*Both normals and colors are assigned to the vertices */
/*Cube is centered at origin so (unnormalized) normals
are the same as the vertex values */

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


	GLfloat vertices[] = {-1.0,-1.0,-1.0,1.0,-1.0,-1.0,
	1.0,1.0,-1.0, -1.0,1.0,-1.0, -1.0,-1.0,1.0, 
	1.0,-1.0,1.0, 1.0,1.0,1.0, -1.0,1.0,1.0};

	GLfloat normals[] = {-1.0,-1.0,-1.0,1.0,-1.0,-1.0,
	1.0,1.0,-1.0, -1.0,1.0,-1.0, -1.0,-1.0,1.0, 
	1.0,-1.0,1.0, 1.0,1.0,1.0, -1.0,1.0,1.0};

	GLfloat colors[] = {0.0,0.0,0.0,1.0,0.0,0.0,
	1.0,1.0,0.0, 0.0,1.0,0.0, 0.0,0.0,1.0, 
	1.0,0.0,1.0, 1.0,1.0,1.0, 0.0,1.0,1.0};

    GLubyte cubeIndices[]={0,3,2,1,2,3,7,6,0,4,7,3,1,2,6,5,4,5,6,7,0,1,5,4};



static GLfloat theta[] = {0.0,0.0,0.0};
static GLint axis = 2;

void display(void)
{
/* display callback, clear frame buffer and z buffer,
   rotate cube and draw, swap buffers */

 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glLoadIdentity();
	glRotatef(theta[0], 1.0, 0.0, 0.0);
	glRotatef(theta[1], 0.0, 1.0, 0.0);
	glRotatef(theta[2], 0.0, 0.0, 1.0);

 glDrawElements(GL_QUADS, 24, GL_UNSIGNED_BYTE, cubeIndices);

 glBegin(GL_LINES);
   glVertex3f(0.0,0.0,0.0);
   glVertex3f(1.0,1.0,1.0);
 glEnd();

 glFlush();
	glutSwapBuffers(); 
}

void spinCube()
{

/* Idle callback, spin cube 2 degrees about selected axis */

	theta[axis] += 2.0;
	if( theta[axis] > 360.0 ) theta[axis] -= 360.0;
	glutPostRedisplay();
}

void mouse(int btn, int state, int x, int y)
{

/* mouse callback, selects an axis about which to rotate */

	if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) axis = 0;
	if(btn==GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) axis = 1;
	if(btn==GLUT_RIGHT_BUTTON && state == GLUT_DOWN) axis = 2;
}

void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
        glOrtho(-2.0, 2.0, -2.0 * (GLfloat) h / (GLfloat) w,
            2.0 * (GLfloat) h / (GLfloat) w, -10.0, 10.0);
    else
        glOrtho(-2.0 * (GLfloat) w / (GLfloat) h,
            2.0 * (GLfloat) w / (GLfloat) h, -2.0, 2.0, -10.0, 10.0);
    glMatrixMode(GL_MODELVIEW);
}

void
main(int argc, char **argv)
{

/* need both double buffering and z buffer */

    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutCreateWindow("colorcube");
    glutReshapeFunc(myReshape);
    glutDisplayFunc(display);
    glutIdleFunc(spinCube);
    glutMouseFunc(mouse);
    glEnable(GL_DEPTH_TEST); /* Enable hidden--surface--removal */
 	glEnableClientState(GL_COLOR_ARRAY); 
	glEnableClientState(GL_NORMAL_ARRAY); 
	glEnableClientState(GL_VERTEX_ARRAY);
	glVertexPointer(3, GL_FLOAT, 0, vertices);
    glColorPointer(3,GL_FLOAT, 0, colors); 
    glNormalPointer(GL_FLOAT,0, normals); 
	glColor3f(1.0,1.0,1.0);
    glutMainLoop();
}