/*
 * perspcube: static cube with perspective camera
 *
 * P Flynn 021703: based on Angel's cube.c
 *
 * 
 * This program displays a wireframe cube in perspective.
 * By default, an isometric view is provided, with reasonable defaults.
 *
 * The initial perspective frustum has a large distance between the
 *  front and rear clipping planes.
 *
 * Interaction: left and middle mouse buttons rotate the view if it started
 *  out in the isometric mode (that's the way it runs by default)
 *
 * keyboard commands:
 * 'i' or 'I': toggle isometric mode.  If you leave isometric mode, only
 *  the keyboard commands will work.
 * 
 * 'a', 'A': decrease, or increase, the aspect ratio by 5%
 * 'f', 'F': decrease, or increase, the FOV by 5 degrees
 * 'n', 'N': move the near clipping plane nearer to, or farther from,
 *  the camera
 * 'm', 'M': move the far clipping plane nearer to, or farther from,
 *  the camera.
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <glut.h>
#include <math.h>


	GLfloat vertices[][3] = {{-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[][3] = {{0.3,0.6,0.7},{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}};

void polygon(int a, int b, int c , int d) {
 /* draw a polygon via list of vertices */
 //glBegin(GL_POLYGON);
 glBegin(GL_LINE_LOOP);
 glColor3fv(colors[a]);
 glVertex3fv(vertices[a]);
 glColor3fv(colors[b]);
 glVertex3fv(vertices[b]);
 glColor3fv(colors[c]);
 glVertex3fv(vertices[c]);
 glColor3fv(colors[d]);
 glVertex3fv(vertices[d]);
 glEnd();
 }

void colorcube(void) {
 /* map vertices to faces */
 polygon(0,3,2,1);
 polygon(2,3,7,6);
 polygon(0,4,7,3);
 polygon(1,2,6,5);
 polygon(4,5,6,7);
 polygon(0,1,5,4);
 }

/*
 * The camera:
 *  - looks at the origin always
 *  - is located on a sphere of radius r 
 *  - theta and phi control eye point and view-up vector
 *
 * Note: tune "r" and front/rear clipping planes
 * to make sure geometry fits (by default)
 */

static GLfloat fovy=90.0,
               aspect=1.0,
               near=1.0,far=30.0;

static int isometric=1;

static GLfloat theta = 45.0, phi=45.0;
static GLfloat r = 5;

void display(void) {
 float xeye,yeye,zeye;
/* display callback, clear frame buffer and z buffer,
   rotate cube and draw, swap buffers */
 glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 glMatrixMode(GL_PROJECTION);
 glLoadIdentity();
 gluPerspective(fovy,aspect,near,far);
 glMatrixMode(GL_MODELVIEW);
 glLoadIdentity();
 if (isometric) {
  xeye = r * cos(phi*M_PI/180.0) * cos(theta*M_PI/180.0);
  yeye = r * cos(phi*M_PI/180.0) * sin(theta*M_PI/180.0);
  zeye = r * sin(phi*M_PI/180.0);
  gluLookAt(xeye,yeye,zeye,    // eye
            0.0,0.0,0.0,    // at
            0.0,0.0,1.0);   // vup
  } else {
  glTranslatef(0.0,0.0,-5.0);  // back up along z axis
  }
 
 glLineWidth(3.0);
 glBegin(GL_LINES);
  glColor3f(1.0,0.0,0.0);
  glVertex3f(0.0,0.0,0.0);
  glVertex3f(1.5,0.0,0.0);
  glColor3f(0.0,1.0,0.0);
  glVertex3f(0.0,0.0,0.0);
  glVertex3f(0.0,1.5,0.0);
  glColor3f(0.0,0.0,1.0);
  glVertex3f(0.0,0.0,0.0);
  glVertex3f(0.0,0.0,1.5);
 glEnd();
 colorcube();
 glFlush();
 glutSwapBuffers();
}


void keyboard(unsigned char key,int x,int y) {
 switch(key) {
  case 'a': aspect /= 1.05; break;             //5% deflate aspect
  case 'A': aspect *= 1.05; break;
  case 'f': fovy  -= 5.0; break;               // 5 degree deinflate fov
  case 'F': fovy += 5.0; break;
  case 'n': near -= 0.05; break;
  case 'N': near += 0.05; break;
  case 'm': far -= 0.05; break;
  case 'M': far += 0.05; break;
  case 'q': exit(0); break;
  case 'r': // reset
   aspect = 1.0; fovy = 90.0; near = 1.0; far = 30.0;  isometric=1;
   break;
  case 'i': case 'I': isometric = 1-isometric; break;
  default: break; // nothing
  }
 glutPostRedisplay();
 }
 
void mouse(int btn, int state, int x, int y) {
 if(btn==GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
  theta += 2;
  if (theta >= 360.0) theta -= 360.0;
  };
 if(btn==GLUT_MIDDLE_BUTTON && state == GLUT_DOWN) {
  phi += 2;
  if (phi >= 360.0) phi -= 360.0;
  };
 glutPostRedisplay();
}


 /* pjf note: this function is called prior to first display, so can be
    used as an init function as well... I think that's what Angel did here */
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)
{
    glutInit(&argc, argv);

/* need both double buffering and z buffer */

    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
    glutInitWindowSize(500, 500);
    glutCreateWindow("colorcube");
    glutReshapeFunc(myReshape);
    glutDisplayFunc(display);
    glutKeyboardFunc(keyboard);
    glutMouseFunc(mouse);
	   glEnable(GL_DEPTH_TEST); /* Enable hidden--surface--removal */
   /* pjf this should be in a separate init function! */
   //glShadeModel(GL_FLAT);
    glutMainLoop();
}