Tactical rotation

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Revision as of 06:13, 25 November 2006 by *>Tremby (link/last edit was me)
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The New Tetris uses smooth falling animation for tetrominoes. The way this implementation mixes the falling animation with collision detection means that when a tetromino must be moved under an overhang to reach a ledge, by the time it has moved left one space with no support it has dropped more than zero spaces. In some cases it can therefore not reach a ledge.

Nothing can be done in the case of the O piece:

OO
GGGOO
GGGG
GGG--
GGG--G
GGGGGGG
GGGGGGGG

There is no problem getting the O piece to here

OO
GGGOO
GGGG
GGG--
GGG--G
GGGGGG
GGGGGGG

But if the ledge is further under the overhang we have a problem

GGG
GGGG
GGGOO
GGGOOG
GGGGGG
GGGGGGG

The piece can not move left until this point

GGG
GGGG
GGG
GGGOOG
GGGGGOOG
GGGGGGG

It cannot move left two spaces before it has dropped more than zero spaces

There are, however, ways of getting a piece other than O further under the overhang by making use of "tactical rotation": rotating the piece in the right direction at the right time.

Examples

L/J shuffle

This is useful for completing spiral L monosquares on the left and spiral J monosquares on the right (in which case the move is reversed).

LL
L
L
GGGG
GG--
GGG-
GGG-

Once the L is clear of the overhang it needs to slide two positions left to lock in place. This can't be done just by holding left

LL
GGGGL
GGL
GGG
GGG

Firm drop the L to hang off the edge

Hold left, rotate clockwise then anticlockwise in quick succession
GGGLL
GGL
GGGL
GGG

The L is moving through the corner piece. Keep holding left and soft drop, so it slides left as soon as it can.

GGGG
GGLL
GGGL
GGGL

Completed square

If the space above the block is already occupied in such a way that the L cannot be overhung as in the second figure, a trickier version can be performed:

GGL
GGGLLL
GGGG
GG--
GGG-
GGG-

Lower the L in this orientation

GG
GGGL
GGGGLLL
GG
GGG
GGG

Start to hold left

GG
GGG
GGGGL
GGLLL
GGG
GGG

Just as the L begins to move left, rotate anticlockwise

GG
GGG
GGGLL
GGL
GGGL
GGG

The L is moving through the corner piece: keep holding left and soft drop it into place

GG
GGG
GGGG
GGLL
GGGL
GGGL

Finished square

S/Z wiggle

This move is required for ZLLZ/SJJS and TTLZ/TTJS multisquares. The move is reversed for SJJS and TTJS multisquares.

C
GGG
GG
GGG
GGGG

The space marked with must be free

ZZ
ZZ
GGG-
GG--
GG-G
GGGG

That surely won't fit...

Z
GGGZZ
GGZ
GGG
GGGG

Firm drop to here, then rotate clockwise then anticlockwise in quick succession

Z
GGZZ
GGZ
GGG
GGGG

The Z piece is sliding through this position. Firm drop it.

GGGZ
GGZZ
GGZG
GGGG

Job done

Reaching under overhangs

This works in a similar way to the trickier version of the L/J shuffle.

SS
GGGGSS
G-
G--
GG-
G

Hold left from here

GGGGSS
GSS
G
GG
G

As soon as the piece starts moving left, rotate anticlockwise (check if direction matters)

GGGG
GS
GSS
GGS
G
L
LLL
GGGG
GS--
GSS-
GGS-
G

Now use the L/J shuffle

This can also be done with I pieces:

I
GGGGGI
GGGGGI
GGGGGI
G-
G-
G-
G-
GG

Just holding left from here won't get the I piece in place

GGGGG
GGGGG
GGGGGIIII
G
G
G
G
GG

Hold left from here

GGGGG
GGGGG
GGGGG
G
G
GIIII
G
GG

As long as the gravity isn't too strong at this point in the game, you'll get to here (or a space further down)

GGGGG
GGGGG
GGGGG
GI
GI
GI
GI
GG

Rotate the I piece into place

Building a T monosquare quickly

The quickest way to add the final piece of a T monosquare is to spin it into place:

T
TT
T
GGG-
GG--
GGG-
GGGG
T
TT
T
GGG-
GG--
GGG-
GGGG

Firm drop the backwards-oriented T piece

GGGT
GGTT
GGGT
GGGG

Rotate the piece twice quickly

GGGT
GGTT
GGGT
GGGG

Finished square

If there is no free space above:

GGGGT
GGGGTT
GGGGT
GGGG
GGG-
GG--
GGG-
GGGG
GGGG
GGGGT
GGGGTT
GGGGT
GGG
GG
GGG
GGGG

With the T piece oriented backwards hold left and soft drop

GGGG
GGGG
GGGG
GGGG
GGGT
GGTT
GGGT
GGGG

It catches in the gap. Rotate the piece twice quickly

GGGG
GGGG
GGGG
GGGG
GGGT
GGTT
GGGT
GGGG

Finished square