swing - Java Tetris - Using transpose to rotate a piece -

i'm building tetris in java fun side project , working on rotations.

i hard coding each rotation proving quite tedious.

that being said, going try matrix rotations using linear algebra, on mathematics.se recommended try transposing. given description, tried drawing out. did drawings correct?

from that, i'm not trying code transpose, lost in code.

public void gettranspose() {     tile[][] gridtranspose = transpose();     system.out.println();     system.out.println("b`:");     (int j = 0; j < gridtranspose.length; j++) {         (int = 0; < gridtranspose[j].length-1; i++) {             system.out.print("(" + + ", " + j + ") ");         }         system.out.println();     } }  public tile[][] transpose() {     tile gridt[][];     gridt = new tile[width][height];     system.out.println("b:");     for(int = 0; < grid.length; i++) {         for(int j = 0; j < grid[i].length-1; j++) {             system.out.print("(" + + ", " + j + ") ");             gridt[j][i] = grid[i][j];          }         system.out.println();     }     return gridt;    } 

this outputs seemingly correct transposed graph?

b:

(0, 0) (0, 1) (0, 2) (0, 3) (0, 4) (0, 5) (0, 6) (0, 7) (0, 8)  (1, 0) (1, 1) (1, 2) (1, 3) (1, 4) (1, 5) (1, 6) (1, 7) (1, 8)  (2, 0) (2, 1) (2, 2) (2, 3) (2, 4) (2, 5) (2, 6) (2, 7) (2, 8)  (3, 0) (3, 1) (3, 2) (3, 3) (3, 4) (3, 5) (3, 6) (3, 7) (3, 8)  (4, 0) (4, 1) (4, 2) (4, 3) (4, 4) (4, 5) (4, 6) (4, 7) (4, 8)  (5, 0) (5, 1) (5, 2) (5, 3) (5, 4) (5, 5) (5, 6) (5, 7) (5, 8)  (6, 0) (6, 1) (6, 2) (6, 3) (6, 4) (6, 5) (6, 6) (6, 7) (6, 8)  (7, 0) (7, 1) (7, 2) (7, 3) (7, 4) (7, 5) (7, 6) (7, 7) (7, 8)  (8, 0) (8, 1) (8, 2) (8, 3) (8, 4) (8, 5) (8, 6) (8, 7) (8, 8)  (9, 0) (9, 1) (9, 2) (9, 3) (9, 4) (9, 5) (9, 6) (9, 7) (9, 8)  

b`:

(0, 0) (1, 0) (2, 0) (3, 0) (4, 0) (5, 0) (6, 0) (7, 0) (8, 0)  (0, 1) (1, 1) (2, 1) (3, 1) (4, 1) (5, 1) (6, 1) (7, 1) (8, 1)  (0, 2) (1, 2) (2, 2) (3, 2) (4, 2) (5, 2) (6, 2) (7, 2) (8, 2)  (0, 3) (1, 3) (2, 3) (3, 3) (4, 3) (5, 3) (6, 3) (7, 3) (8, 3)  (0, 4) (1, 4) (2, 4) (3, 4) (4, 4) (5, 4) (6, 4) (7, 4) (8, 4)  (0, 5) (1, 5) (2, 5) (3, 5) (4, 5) (5, 5) (6, 5) (7, 5) (8, 5)  (0, 6) (1, 6) (2, 6) (3, 6) (4, 6) (5, 6) (6, 6) (7, 6) (8, 6)  (0, 7) (1, 7) (2, 7) (3, 7) (4, 7) (5, 7) (6, 7) (7, 7) (8, 7)  (0, 8) (1, 8) (2, 8) (3, 8) (4, 8) (5, 8) (6, 8) (7, 8) (8, 8)  (0, 9) (1, 9) (2, 9) (3, 9) (4, 9) (5, 9) (6, 9) (7, 9) (8, 9)  

so questions are:

1) drawing above correct interpretation of description?

2) correctly generating transposed graph?

3) if so, how should paint rotated block... should replace grid[row][col] transpose()?

public void paintcomponent(graphics g) {     g.setcolor(color.black);     g.fillrect(0, 0, getwidth(), getheight());     for(int row = 0; row < grid.length; row++) {         for(int col = 0; col < grid[row].length; col++) {             if(grid[row][col] != null) {                 //if there non-null space, tetris piece.. fill red                 if (grid[row][col].getcolor() != null) {                     g.setcolor(grid[row][col].getcolor());                     g.fillrect(row * tilesize, col * tilesize, tilesize, tilesize);                     g.setcolor(color.white);                     g.drawstring("(" + row + ", " + col + ")", row * tilesize, col * tilesize+10);                 }                        }         }     } } 

thanks!

transposing alone won't work of normal tetris pieces. example, take piece shaped this:

xx_ _xx ___ 

when transpose it, end this:

x__ xx_ _x_ 

so rather think particular piece, think happens when work square corners labeled:

a_b ___ d_c 

this make clear if rotation or not. let's @ transpose:

a_d ___ b_c 

in order clockwise rotation, can flip sideways:

d_a ___ c_b 

performing same operation again should give full half rotation started. take transpose:

d_c ___ a_b 

and flip it:

c_d ___ b_a 

so in order clockwise rotation, take transpose , flip it. happens if opposite, flip , take transpose? working previous orientation, if flip it:

d_c ___ a_b 

now take transpose:

d_a ___ c_b 

and we're had after 1 rotate - counterclockwise rotation. transposing alone won't work, transposing combined horizontal flip need!

as questions,

1. i'm not sure drawing correct interpretation. based on comments left suspect may have misunderstood them, why made drawings above show needs happen.

2. yes, correctly transposed graph. don't want use gridtranspose[j].length-1 in loops, cuts off 1 column.

3. to paint rotated block, suggest having separate variable holding current piece. if piece @ x,y, put in paintcomponent method:

   for(int row = 0; row < piece.length(); row++) {     for(int col = 0; col < piece.width(); piece++) {         if(piece.hasblockat(row, col) {             g.setcolor(piece.getcolorat(row, col));             g.fillrect((row+x) * tilesize, (col+y) * tilesize, tilesize, tilesize);         }     }  }