// 3D Cube Rotation

// http://www.speich.net/computer/moztesting/3d.htm

// Created by Simon Speich

var Q = new Array();

var MTrans = new Array();  // transformation matrix

var MQube = new Array();  // position information of qube

var I = new Array();      // entity matrix

var Origin = new Object();

var Testing = new Object();

var LoopTimer;

var DisplArea = new Object();

DisplArea.Width = 300;

DisplArea.Height = 300;

function DrawLine(From, To) {

  var x1 = From.V[0];

  var x2 = To.V[0];

  var y1 = From.V[1];

  var y2 = To.V[1];

  var dx = Math.abs(x2 - x1);

  var dy = Math.abs(y2 - y1);

  var x = x1;

  var y = y1;

  var IncX1, IncY1;

  var IncX2, IncY2;  

  var Den;

  var Num;

  var NumAdd;

  var NumPix;

  if (x2 >= x1) {  IncX1 = 1; IncX2 = 1;  }

  else { IncX1 = -1; IncX2 = -1; }

  if (y2 >= y1)  {  IncY1 = 1; IncY2 = 1; }

  else { IncY1 = -1; IncY2 = -1; }

  if (dx >= dy) {

    IncX1 = 0;

    IncY2 = 0;

    Den = dx;

    Num = dx / 2;

    NumAdd = dy;

    NumPix = dx;

  }

  else {

    IncX2 = 0;

    IncY1 = 0;

    Den = dy;

    Num = dy / 2;

    NumAdd = dx;

    NumPix = dy;

  }

  NumPix = Math.round(Q.LastPx + NumPix);

  var i = Q.LastPx;

  for (; i < NumPix; i++) {

    Num += NumAdd;

    if (Num >= Den) {

      Num -= Den;

      x += IncX1;

      y += IncY1;

    }

    x += IncX2;

    y += IncY2;

  }

  Q.LastPx = NumPix;

}

function CalcCross(V0, V1) {

  var Cross = new Array();

  Cross[0] = V0[1]*V1[2] - V0[2]*V1[1];

  Cross[1] = V0[2]*V1[0] - V0[0]*V1[2];

  Cross[2] = V0[0]*V1[1] - V0[1]*V1[0];

  return Cross;

}

function CalcNormal(V0, V1, V2) {

  var A = new Array();   var B = new Array(); 

  for (var i = 0; i < 3; i++) {

    A[i] = V0[i] - V1[i];

    B[i] = V2[i] - V1[i];

  }

  A = CalcCross(A, B);

  var Length = Math.sqrt(A[0]*A[0] + A[1]*A[1] + A[2]*A[2]); 

  for (var i = 0; i < 3; i++) A[i] = A[i] / Length;

  A[3] = 1;

  return A;

}

function CreateP(X,Y,Z) {

  this.V = [X,Y,Z,1];

}

// multiplies two matrices

function MMulti(M1, M2) {

  var M = [[],[],[],[]];

  var i = 0;

  var j = 0;

  for (; i < 4; i++) {

    j = 0;

    for (; j < 4; j++) M[i][j] = M1[i][0] * M2[0][j] + M1[i][1] * M2[1][j] + M1[i][2] * M2[2][j] + M1[i][3] * M2[3][j];

  }

  return M;

}

//multiplies matrix with vector

function VMulti(M, V) {

  var Vect = new Array();

  var i = 0;

  for (;i < 4; i++) Vect[i] = M[i][0] * V[0] + M[i][1] * V[1] + M[i][2] * V[2] + M[i][3] * V[3];

  return Vect;

}

function VMulti2(M, V) {

  var Vect = new Array();

  var i = 0;

  for (;i < 3; i++) Vect[i] = M[i][0] * V[0] + M[i][1] * V[1] + M[i][2] * V[2];

  return Vect;

}

// add to matrices

function MAdd(M1, M2) {

  var M = [[],[],[],[]];

  var i = 0;

  var j = 0;

  for (; i < 4; i++) {

    j = 0;

    for (; j < 4; j++) M[i][j] = M1[i][j] + M2[i][j];

  }

  return M;

}

function Translate(M, Dx, Dy, Dz) {

  var T = [

  [1,0,0,Dx],

  [0,1,0,Dy],

  [0,0,1,Dz],

  [0,0,0,1]

  ];

  return MMulti(T, M);

}

function RotateX(M, Phi) {

  var a = Phi;

  a *= Math.PI / 180;

  var Cos = Math.cos(a);

  var Sin = Math.sin(a);

  var R = [

  [1,0,0,0],

  [0,Cos,-Sin,0],

  [0,Sin,Cos,0],

  [0,0,0,1]

  ];

  return MMulti(R, M);

}

function RotateY(M, Phi) {

  var a = Phi;

  a *= Math.PI / 180;

  var Cos = Math.cos(a);

  var Sin = Math.sin(a);

  var R = [

  [Cos,0,Sin,0],

  [0,1,0,0],

  [-Sin,0,Cos,0],

  [0,0,0,1]

  ];

  return MMulti(R, M);

}

function RotateZ(M, Phi) {

  var a = Phi;

  a *= Math.PI / 180;

  var Cos = Math.cos(a);

  var Sin = Math.sin(a);

  var R = [

  [Cos,-Sin,0,0],

  [Sin,Cos,0,0],

  [0,0,1,0],   

  [0,0,0,1]

  ];

  return MMulti(R, M);

}

function DrawQube() {

  // calc current normals

  var CurN = new Array();

  var i = 5;

  Q.LastPx = 0;

  for (; i > -1; i--) CurN[i] = VMulti2(MQube, Q.Normal[i]);

  if (CurN[0][2] < 0) {

    if (!Q.Line[0]) { DrawLine(Q[0], Q[1]); Q.Line[0] = true; };

    if (!Q.Line[1]) { DrawLine(Q[1], Q[2]); Q.Line[1] = true; };

    if (!Q.Line[2]) { DrawLine(Q[2], Q[3]); Q.Line[2] = true; };

    if (!Q.Line[3]) { DrawLine(Q[3], Q[0]); Q.Line[3] = true; };

  }

  if (CurN[1][2] < 0) {

    if (!Q.Line[2]) { DrawLine(Q[3], Q[2]); Q.Line[2] = true; };

    if (!Q.Line[9]) { DrawLine(Q[2], Q[6]); Q.Line[9] = true; };

    if (!Q.Line[6]) { DrawLine(Q[6], Q[7]); Q.Line[6] = true; };

    if (!Q.Line[10]) { DrawLine(Q[7], Q[3]); Q.Line[10] = true; };

  }

  if (CurN[2][2] < 0) {

    if (!Q.Line[4]) { DrawLine(Q[4], Q[5]); Q.Line[4] = true; };

    if (!Q.Line[5]) { DrawLine(Q[5], Q[6]); Q.Line[5] = true; };

    if (!Q.Line[6]) { DrawLine(Q[6], Q[7]); Q.Line[6] = true; };

    if (!Q.Line[7]) { DrawLine(Q[7], Q[4]); Q.Line[7] = true; };

  }

  if (CurN[3][2] < 0) {

    if (!Q.Line[4]) { DrawLine(Q[4], Q[5]); Q.Line[4] = true; };

    if (!Q.Line[8]) { DrawLine(Q[5], Q[1]); Q.Line[8] = true; };

    if (!Q.Line[0]) { DrawLine(Q[1], Q[0]); Q.Line[0] = true; };

    if (!Q.Line[11]) { DrawLine(Q[0], Q[4]); Q.Line[11] = true; };

  }

  if (CurN[4][2] < 0) {

    if (!Q.Line[11]) { DrawLine(Q[4], Q[0]); Q.Line[11] = true; };

    if (!Q.Line[3]) { DrawLine(Q[0], Q[3]); Q.Line[3] = true; };

    if (!Q.Line[10]) { DrawLine(Q[3], Q[7]); Q.Line[10] = true; };

    if (!Q.Line[7]) { DrawLine(Q[7], Q[4]); Q.Line[7] = true; };

  }

  if (CurN[5][2] < 0) {

    if (!Q.Line[8]) { DrawLine(Q[1], Q[5]); Q.Line[8] = true; };

    if (!Q.Line[5]) { DrawLine(Q[5], Q[6]); Q.Line[5] = true; };

    if (!Q.Line[9]) { DrawLine(Q[6], Q[2]); Q.Line[9] = true; };

    if (!Q.Line[1]) { DrawLine(Q[2], Q[1]); Q.Line[1] = true; };

  }

  Q.Line = [false,false,false,false,false,false,false,false,false,false,false,false];

  Q.LastPx = 0;

}

function Loop() {

  if (Testing.LoopCount > Testing.LoopMax) return;

  var TestingStr = String(Testing.LoopCount);

  while (TestingStr.length < 3) TestingStr = "0" + TestingStr;

  MTrans = Translate(I, -Q[8].V[0], -Q[8].V[1], -Q[8].V[2]);

  MTrans = RotateX(MTrans, 1);

  MTrans = RotateY(MTrans, 3);

  MTrans = RotateZ(MTrans, 5);

  MTrans = Translate(MTrans, Q[8].V[0], Q[8].V[1], Q[8].V[2]);

  MQube = MMulti(MTrans, MQube);

  var i = 8;

  for (; i > -1; i--) {

    Q[i].V = VMulti(MTrans, Q[i].V);

  }

  DrawQube();

  Testing.LoopCount++;

  Loop();

}

function Init(CubeSize) {

  // init/reset vars

  Origin.V = [150,150,20,1];

  Testing.LoopCount = 0;

  Testing.LoopMax = 50;

  Testing.TimeMax = 0;

  Testing.TimeAvg = 0;

  Testing.TimeMin = 0;

  Testing.TimeTemp = 0;

  Testing.TimeTotal = 0;

  Testing.Init = false;

  // transformation matrix

  MTrans = [

  [1,0,0,0],

  [0,1,0,0],

  [0,0,1,0],

  [0,0,0,1]

  ];

  // position information of qube

  MQube = [

  [1,0,0,0],

  [0,1,0,0],

  [0,0,1,0],

  [0,0,0,1]

  ];

  // entity matrix

  I = [

  [1,0,0,0],

  [0,1,0,0],

  [0,0,1,0],

  [0,0,0,1]

  ];

  // create qube

  Q[0] = new CreateP(-CubeSize,-CubeSize, CubeSize);

  Q[1] = new CreateP(-CubeSize, CubeSize, CubeSize);

  Q[2] = new CreateP( CubeSize, CubeSize, CubeSize);

  Q[3] = new CreateP( CubeSize,-CubeSize, CubeSize);

  Q[4] = new CreateP(-CubeSize,-CubeSize,-CubeSize);

  Q[5] = new CreateP(-CubeSize, CubeSize,-CubeSize);

  Q[6] = new CreateP( CubeSize, CubeSize,-CubeSize);

  Q[7] = new CreateP( CubeSize,-CubeSize,-CubeSize);

  // center of gravity

  Q[8] = new CreateP(0, 0, 0);

  // anti-clockwise edge check

  Q.Edge = [[0,1,2],[3,2,6],[7,6,5],[4,5,1],[4,0,3],[1,5,6]];

  // calculate squad normals

  Q.Normal = new Array();

  for (var i = 0; i < Q.Edge.length; i++) Q.Normal[i] = CalcNormal(Q[Q.Edge[i][0]].V, Q[Q.Edge[i][1]].V, Q[Q.Edge[i][2]].V);

  // line drawn ?

  Q.Line = [false,false,false,false,false,false,false,false,false,false,false,false];

  // create line pixels

  Q.NumPx = 9 * 2 * CubeSize;

  for (var i = 0; i < Q.NumPx; i++) CreateP(0,0,0);

  MTrans = Translate(MTrans, Origin.V[0], Origin.V[1], Origin.V[2]);

  MQube = MMulti(MTrans, MQube);

  var i = 0;

  for (; i < 9; i++) {

    Q[i].V = VMulti(MTrans, Q[i].V);

  }

  DrawQube();

  Testing.Init = true;

  Loop();

}

for ( var i = 20; i <= 160; i *= 2 ) {

  Init(i);

}

Q = null;

MTrans = null;

MQube = null;

I = null;

Origin = null;

Testing = null;

LoopTime = null;

DisplArea = null;