## here a 3D graphics course

links :
http://who.is.free.fr/wiki/index.php?e=project&edit=Rubiks
http://rzr.online.fr/java.htm

BTW, I'd like a to own a "rubiks clock" or/and a "powerball" toy which is 1 euro on ebay :)


# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

Faces

  y
  |\
  |_\
  O  x

  int x=1; int y=1;
  vertex = { { 0, 0, 0 } ,  { 0,0,x } ,  {0,y,0 } };
  faces = { { 0 , 1 , 2 } };  // index in vertex array , here : O, x, y
  color = { 0x00FF0000 } ; // red color

For a square (which is 2 triangles) :

  y __
  |\ |
  |_\|
  O    x

  int x=1; int y=1;
  vertex = { 0, 0, 0,   0,0,x,  0,y,0 ,  x,y,0 };
  faces = { {0,1,2} , {1,2,3} };
  color = { 0x0099FF00, 0x0000FF00 } ; // two triangles are green

helper :

  2  3
  0  1


# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
2x2 scare = 3x3 = 9 vertex (on xy plane)

    +y
    |
  .  .  .
  .  o  .   --> +x
  .  .  .


  int x = 1; int y = 1;
  coords = {
  * x , y ,           0 , y ,               x , y ,    // row 1
    *x , 0 ,           0 , 0 ,               x , 0 ,    // row 2
  * x , -y ,          0 , -y ,              x , -y ,   // row 3
  }

helper : read array pairs like :

  0  1  2
  3  4  5
  6  7  8


>>> TODO : make the face array

faces = { {0,1,2}, {1,2,3}, {1,0,4}, { 0,4,5}, {0,6,5}, {6,5,7}, {0,8,2}, {8,0,6} : FALSE ==================
};

wrong : { 0 1 2 } is not a triangle because points are aligned

answer is : from up to down , left to right :
  { 0 , 1 , 3 } , { 3 , 1 , 4 } , // for up left scare
  { 1 , 2 , 4 } , { 4 , 2 , 5 } , //     up right scare
  { 3 , 4 , 6 } , { 6 , 4 , 7 } , //     bottom left
  { 4 , 5 , 7 } , { 7 , 5 , 8 } , //     bottom right

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
now do it again in 3D :

  int z= 1;
  int x = 1;
  int y = 1;


  coords= {
  * x , y , -z          0 , y , -z              x , y , -z,  // row 1
    *x , 0 , -z          0 , 0 , -z              x , 0 ,  -z,  // row 2
  * x , -y , -z         0 , -y , -z             x , -y , -z,  // row 3
  /// ^ far plane
  * x , y , 0          0 , y , 0              x , y , 0,  // row 4
    *x , 0 , 0          0 , 0 , 0              x , 0 , 0,  // row 5
  * x , -y , 0         0 , -y ,0              x , -y , 0,  // row 6
  /// ^ center plane
  * x , y , +z          0 , y , +z              x , y , +z,  // row 7
    *x , 0 , +z          0 , 0 , +z              x , 0 ,  +z,  // row 8
  * x , -y , +z         0 , -y , +z             x , -y , +z,  // row 9
  /// ^ near plane
  }

>>> TODO : make the face array

helper:

  0  1  2
  3  4  5
  6  7  8
rear side (-z)

for middle side (z=0)  add 9 to rear side vertex indices

for front side (+z) add 2*9 to rear side vertex indices


faces = { {0,1,2}, {1,2,3}, : FALSE ==================
	  {1,0,4}, {0,4,5},: FALSE ==================
	  {0,6,5}, {6,5,7},: FALSE ==================
	  {0,8,2}, {8,0,6}: FALSE ==================
};

Wrong there must be : 2 * 4 * 6 triplets
(2 triangle per square, 4 square per faces, 6 faces)


# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #
Once done, make a color array (one color per face), a color is represented as a triplet of values ( { R, G, B} } or stored in a 32 bit int : 0x00RRGGBB ;

Once done, make a function that "rotate" the colors in the cube :
void rotateRow( int row_indice, bool right_or_left) { }

this method only swap the colors on a full slice of the cube  (think 3D)
thoses ones are a the most complicated.

As well :
void rotateCols( int col_indice, bool right_or_left) { }

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #

now make the  ">>> TODO :" parts


BTW, I'd like a to own a "rubiks clock" or/and a "powerball" toy which is 1 euro on ebay :)