/* Scatters a bunch of blocks around a scene, to demonstrate the
   translate-rotate-scale affine transformations.

Written by Scott D. Anderson
scott.anderson@acm.org
Fall 2003
*/

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

/* This file sometimes draws a block "by hand," instead of using the GLUT
   object.  The following array holds the 8 vertices. Unlike the GLUT
   object, which has the origin in the center, this block has the origin
   at one corner.  This makes scaling a little easier sometimes. */

twTriple vertices[8] = {
    {0,0,0},{1,0,0},{1,1,0},{0,1,0},
    {0,0,1},{1,0,1},{1,1,1},{0,1,1}
};

/* This function draws one face of the wire cube given the indices of the
   four vertices.  Since it is wire, it doesn't matter whether the
   vertices are counter-clockwise, but we'll try to do that anyhow. */

void face(int a, int b, int c, int d) {
    glBegin(GL_LINE_LOOP);
    glVertex3fv(vertices[a]);
    glVertex3fv(vertices[b]);
    glVertex3fv(vertices[c]);
    glVertex3fv(vertices[d]);
    glEnd();
}

/* The reference point for this unit cube is the lower left front
   corner. */

void myCube() {
    // This is a little inefficient, since every edge gets drawn twice,
    // since each edge is the boundary between two faces. However, this
    // organizes the code, generalizes to solid objects, and introduces
    // the idea of the inside and outside faces of a surface.
    face(0,1,2,3); // front
    face(7,6,5,4); // back
    face(4,5,1,0); // bottom
    face(1,5,6,2); // right
    face(0,3,7,4); // left
    face(2,6,7,3); // top
}

/* An ordinary display function, drawing a succession of blocks.  Each has
   a different color, so that you can match up the graphic block with the
   code that draws it.  For each block, try to figure out where it is and
   how it looks, just by visualizing the transformations.  That's good
   practice for using the affine transformations in your own modeling. */

void display(void) {
    twDisplayInit();
    twCamera();

    // draw ground
    twColorName(TW_BLACK);
    twGround();

    // origin
    twColorName(TW_WHITE);
    glutWireCube(1);

    // translate only
    twColorName(TW_RED);
    glPushMatrix();
    glTranslatef(2,3,4);
    glutWireCube(1);
    glPopMatrix();

    // translate and scale.  Look out below!
    twColorName(TW_GREEN);
    glPushMatrix();
    glTranslatef(4,0,5);
    glScalef(2,2,2);
    glutWireCube(1);
    glPopMatrix();

    // compensating in the translation
    twColorName(TW_BLUE);
    glPushMatrix();
    glTranslatef(8,1,1);
    glScalef(2,2,2);
    glutWireCube(1);
    glPopMatrix();

    // using a different reference point
    twColorName(TW_MAGENTA);
    glPushMatrix();
    glTranslatef(9,0,1);
    glScalef(2,2,2);
    myCube();
    glPopMatrix();

    // stacking some rotated blocks
    twColorName(TW_YELLOW);
    glPushMatrix();
    glTranslatef(1,1,8);
    glScalef(2,2,2);
    glutWireCube(1);
    glPopMatrix();

    twColorName(TW_ORANGE);
    glPushMatrix();
    glTranslatef(1,3,8);
    glRotatef(30,0,1,0);        // 30 degrees around y
    glScalef(2,2,2);
    glutWireCube(1);
    glPopMatrix();

    twColorName(TW_BROWN);
    glPushMatrix();
    glTranslatef(1,5,8);
    glRotatef(60,0,1,0);        // degrees around y
    glScalef(2,2,2);
    glutWireCube(1);
    glPopMatrix();

    // non-uniform scaling
    twColorName(TW_CYAN);
    glPushMatrix();
    glTranslatef(8,0,8);
    glRotatef(45,0,1,0);        // degrees around y
    glScalef(1,5,1);
    glutWireCube(1);
    glPopMatrix();
    
    twColorName(TW_TEAL);
    glPushMatrix();
    glTranslatef(9,0,9);
    glRotatef(45,0,1,0);        // degrees around y
    glScalef(1,5,1);
    myCube();
    glPopMatrix();

    glFlush();
    glutSwapBuffers();       // necessary for animation
}

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(0,10,0,5,0,10);
  glLineWidth(3);               // nice fat lines.  In this program, we only need to say this once
  twMainInit(); 
  glutMainLoop();
  return 0;
}