Difference between revisions of "Tactical rotation"

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[[Category:Movement]]
 
 
[[Category:Square Methods]]
 
[[Category:Square Methods]]

Revision as of 10:38, 9 September 2019

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
  G GGG
  GGG--
  GGG--  G
 GGGGGG  G
GGGGGGG  G

There is no problem getting the O piece to here

       OO
    GGGOO
  G GGG
  GGG--
  GGG--  G
 GGGGG   G
GGGGGG   G

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

    GGG
  G GGG
  GGG  OO
  GGG  OOG
 GGGGG   G
GGGGGG   G

The piece can not move left until this point

    GGG
  G GGG
  GGG
  GGG OO G
 GGGGGOO G
GGGGGG   G

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

Reaching under overhangs

With I pieces

      I
GGGGG I
GGGGG I
GGGGG I
G-
G-
G-
G-
GG

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

GGGGG
GGGGGI
GGGGGI
G    I
G    I
G
G
GG

Hold left and rotate (either direction) just after this point

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 above or below)

GGGGG
GGGGG
GGGGG
GI
GI
GI
GI
GG

Rotate the I piece into place

With L and J pieces

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) if the space above the block is already occupied in such a way that the L cannot be overhung as in the second figure of the L/J shuffle below.

  GG  L
 GGGLLL
GGGG
GG--
GGG-
GGG-

Lower the L in this orientation

  GG
 GGG  L
GGGGLLL
GG
GGG
GGG

Start to hold left

  GG
 GGG
GGGG  L
GG  LLL
GGG
GGG

Just as the L begins to move left, rotate anticlockwise

  GG
 GGG
GGGLL
GG  L
GGG L
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

With the opposite multisquares (L on the right or J on the left), the third piece requires some tactical rotation if there is not enough support underneath.

     J
     J
 GG JJ
GGG
GGG
G-
G---
GG
 GG J
GGG J
GGGJJ
G
G
GG

Lower the J piece in this orientation, holding left as soon as possible

 GG
GGG J
GGG J
G  JJ
G
GG

The J starts moving left at this point – immediately rotate clockwise

 GG
GGG
GGG
GJ
GJJJ
GG

The piece in place

If there is sufficient free space above the construction, an easier method can be used (shown below).

L/J swing

This is useful when building a spiral L monosquare on the right or a spiral J monosquare on the left as above, provided there is enough free space above the construction.

     J
     J
    JJ
GGG
GGG
G-
G---
GG
 JJJ
GGGJ
GGG
G
G
GG

Firm drop to this position

Rotate clockwise twice in quick succession
GGG
GGG
GJ
GJJJ
GG

The piece in place

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
GG  L
GGG
GGG

Firm drop the L to hang off the edge

Hold left, rotate clockwise then anticlockwise in quick succession
GGGLL
GG  L
GGG L
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

S/Z pop

This move is required for ZLLZ/SJJS, TTLZ/TTJS and LJZI/JLSI multisquares. All rotations should be reversed for the right-hand versions.

   C
GGG
GG
GG G
GGGG

The space marked with CTet.png must be free. The move is easiest if the space to CTet.png's left is also free...

    ZZ
     ZZ
GGG-
GG--
GG-G
GGGG

That surely won't fit...

  ZZ
GGGZZ
GG
GG G
GGGG

Firm drop to here, then rotate in either direction

GGGZ
GGZZ
GGZG
GGGG

Easy

  C
GGG
GG
GG G
GGGG

If the space indicated is taken there are two other ways

  G Z
GGGZZ
GG Z
GG G
GGGG

The easiest is the S/Z wiggle: firm drop to here, then rotate clockwise then anticlockwise in quick succession

  GZ
GGZZ
GGZ
GG G
GGGG

The Z piece is sliding down from this position. Firm drop it.

  G
GGGZ
GGZZ
GGZG
GGGG

Job done

  GZZ
GGG ZZ
GG
GG G
GGGG

The second of the two rotations can be performed alone, but this isn't as quick or easy. To do it, rotate anticlockwise just after the Z is in this position...

  G
GGGZZ
GG  ZZ
GG G
GGGG

...before it gets to here

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
GG TT
GGGT
GGGG

Rotate the piece twice quickly

GGGT
GGTT
GGGT
GGGG

Finished square

If there is no free space above:

GGGG T
GGGG TT
GGGG T
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
GG TT
GGGT
GGGG

It catches in the gap. Rotate the piece twice quickly

GGGG
GGGG
GGGG
GGGG
GGGT
GGTT
GGGT
GGGG

Finished square