Tetris Piece Rotation Algorithm

Question

What are the best algorithms (and explanations) for representing and rotating the pieces of a tetris game? I always find the piece rotation and representation schemes confu

Answer 1

I derived a rotation algorithm from matrix rotations here. To sum it up: If you have a list of coordinates for all cells that make up the block, e.g. [(0, 1), (1, 1), (2, 1), (3, 1)] or [(1, 0), (0, 1), (1, 1), (2, 1)]:

 0123       012
0....      0.#.
1####  or  1###
2....      2...
3....

you can calculate the new coordinates using

x_new = y_old
y_new = 1 - (x_old - (me - 2))

for clockwise rotation and

x_new = 1 - (y_old - (me - 2))
y_new = x_old

for counter-clockwise rotation. me is the maximum extent of the block, i.e. 4 for I-blocks, 2 for O-blocks and 3 for all other blocks.