////////////**************************
// DRAWING
////////////**************************

// preload images (myImages)
function loadImages() {
 myImages = new Array(12);
 myImages[0] = new Image();
 myImages[0].src = "images/0.gif";
 for (var i=0; i<12; i++) {
  myImages[i+1] = new Image();
  myImages[i+1].src = "images/dots"+i+".gif";
 }
}

// craete an empty image
function createImage(name, codeS) {
  document.write('<A HREF="index.html" onMouseOver="' + codeS + '" >');
  document.write("<IMG SRC=images/0.gif NAME=" +name+ 'WIDTH=10 HEIGHT=10>');
  document.write("</A>\n");
}


function createRandomImage(name) {
  var number =  Math.floor(12*Math.random());
  document.write("<IMG SRC=images/dots" +number+ ".gif NAME=" + name+
                 " WIDTH=20 HEIGHT=20>");
}

function createImageArray() {
  for (var y = 0; y < MAX_Y; y++) {
    for (var x = 0; x < MAX_X; x++) {
      createImage("x" + x + "y" + y, "mouseOver("+x+ "," +y+");");
    }
    document.write("<BR>");
  }
}

function drawRandomImage() {
  var x = Math.floor(MAX_X*Math.random());
  var y = Math.floor(MAX_Y*Math.random());
  var i = Math.floor(12*Math.random());
  document.images[x + MAX_X*y].src = myImages[i].src;
}

function drawImage(x,y,i) {
 var k = x + MAX_X*y;	
 if ((k>=0) && (k<(MAX_X)*(MAX_Y)))
    document.images[k].src = myImages[i].src;
}


function drawSphere(x, y, r, i) {
 
 for (var alpha = 0; alpha < 2*3.14; alpha+=3.14/12) {
  drawImage(Math.round(x + r*Math.sin(alpha)),
            Math.round(y + r*Math.cos(alpha)), 
	    i);
 }
}

function sign(a) {
 return (a>0) ? 1 : ((a<0) ? -1 : 0);
}


function drawLine(ax, ay, bx, by, im) {
 
 var dx = bx - ax;
 var dy = by - ay;
 
 var sx = sign(dx);
 var sy = sign(dy);
 var adx,ady;
 
 if ((adx=Math.abs(dx)) > (ady=Math.abs(dy))) {
  var ky = dy/adx;
  var y = ay;
  var x = ax;
  for (var i = 0; i<=adx; x+=sx, y+=ky, i++)
   drawImage(x,Math.round(y), im);
 } else {
  var kx = dx/ady;
  var x = ax;
  var y = ay;
  for (var i = 0; i<=ady; x+=kx, y+=sy, i++)
   drawImage(Math.round(x),y, im);
 }
 
}


// Draw a line into a buffer
function drawLineBuff(ax, ay, bx, by, buffer) {
 
 var dx = bx - ax;
 var dy = by - ay;
 
 var sx = sign(dx);
 var sy = sign(dy);

 var ady=Math.abs(dy);
 
 var kx = dx/ady;
 var x = ax;
 var y = ay;
 for (var i = 0; i<=ady; x+=kx, y+=sy, i++)
  buffer[y] = Math.round(x);

}

function drawPolygon(points, im) {

 minbuff = new Array(MAX_Y);
 maxbuff = new Array(MAX_Y);
 
 var miny = 1000, maxy = -1000;
 
 for (var i=0; i < points.length; i++) {
  var a = points[i];
  var b = points[(i+1)%points.length];
  if (a.y > b.y) {
   drawLineBuff(a.x, a.y, b.x, b.y, maxbuff);
   if (b.y < miny)
    miny = b.y;
   if (a.y > maxy)
    maxy = a.y;
  }
  if (a.y < b.y) {
   drawLineBuff(a.x, a.y, b.x, b.y, minbuff);
   if (a.y < miny)
    miny = a.y;
   if (b.y > maxy)
    maxy = b.y;
  }  
   
 }
 
 for (var y=miny; y<=maxy; y++)
  for (var x=minbuff[y]; x<=maxbuff[y]; x++)
   drawImage(x,y,im);

}

function drawWirePolygon(point, im) {

 for (var i=0; i< points.length; i++) {
  var a = points[i];
  var b = points[(i+1)%points.length];
  drawLine(a.x, a.y, b.x, b.y, im);
 }

}


function animateSphere() {

 x = 10;
 y = 10;
 
 // clear
 // if (r != 2)
 //   drawSphere(x, y, r, 0);

 if (r>=9)
   r = 1; 
  else
   drawSphere(x, y, r, Math.floor(12*Math.random()));

 setTimeout("animateSphere()", 500);
}


function createMatrix() {
  this.a03 = this.a01 = this.a02 = 0;
  this.a10 = this.a13 = this.a12 = 0;
  this.a20 = this.a21 = this.a23 = 0;
  this.a30 = this.a31 = this.a32 = 0;
  this.a00 = this.a11 = this.a22 = this.a33 = 1;
}

function createMatrixRotY(fi) {
  this.a00 = Math.cos(fi); this.a01=0; this.a02=Math.sin(fi); this.a03=0;
  this.a10 = this.a13 = this.a12 = 0; this.a11=1;
  this.a20 = -Math.sin(fi); this.a21=0; this.a22=Math.cos(fi); this.a23=0;
  this.a30 = this.a31 = this.a32 = 0; this.a33=1;
}

function createMatrixRotX(fi) {
  this.a00 = 1; this.a01 =  this.a02 =  this.a03 = 0;
  this.a10 = 0; this.a11 = Math.cos(fi); this.a12=Math.sin(fi); this.a13=0;
  this.a20 = 0; this.a21 = -Math.sin(fi); this.a22=Math.cos(fi); this.a23=0;
  this.a30 = this.a31 = this.a32 = 0; this.a33=1;
}

// constructor
function Point3D(x, y, z) {
 this.x = x;
 this.y = y;
 this.z = z;
 this.w = 1;
}


// Create model of an object from the array of 3D points
// and the array of polygons (indices into the points array separated by -1)
function createModel(model, points, edges) {
 var i,j;

 model.points = new Array(points.length/3);

  for (i=0, j=0; i < points.length; j++) {
   model.points[j] = new Point3D(points[i++],points[i++], points[i++]);
 }

 // only copy by reference
 model.edges = edges;
}




function transformPoint(result, point, matrix) {
 result.x = point.x * matrix.a00 + point.y*matrix.a10 + point.z*matrix.a20 + point.w*matrix.a30;
 result.y = point.x * matrix.a01 + point.y*matrix.a11 + point.z*matrix.a21 + point.w*matrix.a31;
 result.z = point.x * matrix.a02 + point.y*matrix.a12 + point.z*matrix.a22 + point.w*matrix.a32;
 result.w = point.x * matrix.a03 + point.y*matrix.a13 + point.z*matrix.a23 + point.w*matrix.a33;
}

function normalize(point) {
 point.x/=point.w;
 point.y/=point.w;
 point.z/=point.w;
}

function MatrixCompose(m1, m2) {
 var r,c;
 for(r=0; r<4; r++)
  for(c=0; c<4; c++) 
    this["a"+r+c] = m1["a" + r + "0"]*m2["a0" + c] + m1["a" + r + "1"]*m2["a1" + c] +
                      m1["a" + r + "2"]*m2["a2" + c] + m1["a" + r + "3"]*m2["a3" + c];

}

function matrixCopy(dest, src) {
 var r,c;
 for(r=0; r<4; r++)
  for(c=0; c<4; c++) 
   dest["a"+r+c] = src["a"+r+c]; 
}

function rotate(matrix) {
 fiY+=0.1;
 fiX+=0.2;
 var m1 = new createMatrixRotY(fiY);
 var m2 = new createMatrixRotX(fiX);
 var m3 = new MatrixCompose(m1, m2);
 matrixCopy(matrix, m3);
}

function drawWireModel(model, matrix, im) {
 
 // crate an array of tranformed points
 var i;
 var transformed = new Array(model.points.length);
 for (i=0; i < model.points.length; i++) {
  transformed[i] = new Object();
  transformPoint(transformed[i], model.points[i], matrix);
  normalize(transformed[i]);
 }

 var a,b;
 // draw the edges
 for (i=0; i < model.edges.length; i+=2) {
    a = transformed[model.edges[i]];
    b = transformed[model.edges[i+1]];
    drawLine(
    Math.round(centerX + a.x*PERSP/(a.z+centerZ)),
    Math.round(centerY + a.y*PERSP/(a.z+centerZ)),
    Math.round(centerX + b.x*PERSP/(b.z+centerZ)),
    Math.round(centerY + b.y*PERSP/(b.z+centerZ)),
    im);
  } 

}


// create an axis aligned box 
function Box(x, y, z, points, edges) {

  x/=2;
  y/=2;
  z/=2;
  points[0] = new Point3D(-x,-y,-z);
  points[1] = new Point3D(x,-y,-z);
  points[2] = new Point3D(x,y,-z);
  points[3] = new Point3D(-x,y,-z);
  points[4] = new Point3D(-x,-y,z);
  points[5] = new Point3D(x,-y,z);
  points[6] = new Point3D(x,y,z);
  points[7] = new Point3D(-x,y,z);
  
  var i=0;

  edges[i++] = 0; edges[i++] = 1;
  edges[i++] = 1; edges[i++] = 2;
  edges[i++] = 2; edges[i++] = 3;
  edges[i++] = 3; edges[i++] = 0;

  edges[i++] = 4; edges[i++] = 5;
  edges[i++] = 5; edges[i++] = 6;
  edges[i++] = 6; edges[i++] = 7;
  edges[i++] = 7; edges[i++] = 4;

  edges[i++] = 0; edges[i++] = 4;
  edges[i++] = 1; edges[i++] = 5;
  edges[i++] = 2; edges[i++] = 6;
  edges[i++] = 3; edges[i++] = 7;

  
  this.points = points;
  this.edges = edges;
}

function animateRotation() {

 drawWireModel(model, matrix, 0); 
 rotate(matrix);
 drawWireModel(model, matrix, 5); 
 
 setTimeout("animateRotation()", 100);
}