Match 3 Unity #5 - Swapping & Matching!

A video to show the results of implementation:

From our Trello board, this is our current progress and what's next. In the previous post I completed the following regarding the grid and it's elements:

• Grid alignment and scaling

• Randomization of grid elements

• Falling of grid elements to fill space

• An obstacle as an extra element type

Now that these have been finished, I moved on to developing the main mechanics for swapping elements to create matches.

This week, I implemented:

• Swapping, based on valid 'matching' conditions

• Removal of elements when matched

• Filling the board after a match is made

Criteria for making matches:

• Minimum of 3 elements of the same appearance

• Horizontal or vertical

• L and T shaped matches should work

How elements are cleared

I decided to create a script to attach to anything which can be cleared off the board- this way I can easily reuse code to apply behaviours to multiple game objects, if I need to in the future. See "Clearable Element"- an animation can be set which will be played before an element is cleared, too. This will be included in the future- for now, there is no clearance animation, but the element is simply destroyed after it is moved to it's new position.

Clearing an element is called as a coroutine where, if there is an animation supplied, the duration of the animation is waited for before the element is destroyed.

Input Functions

The GameElement script handles direct input. Containing a reference to the board manager script, the mouse input functions call these functions in BoardManager. To summarise: player taps element > player drags to select an adjacent element > player releases press > game initiates a swap of the two elements.

Swapping Elements

The "SwapElements" function houses its own logic and calls to four other functions I have implemented: "GetMatch" houses the logic for detecting matches between elements; "Move" (of the "MovableComponent" script) facilitates the visual aspect of element swapping; "ClearValidMatches" ensures that all elements which are matched - even inadvertantly - are cleared; "Fill" is ran as a coroutine- it ensures that all empty spaces are filled after matches are made.

A summary of how matches are determined (the code is over 100 lines long at the moment):

ITERATE horizontally:
    COMPARE Appearances (from appearance component) of the adjacent     
    cells
    IF they MATCH in appearance, ADD to list X(horizontal matches)
END OF ITERATIONS
IF matches were found:
    RETURN list X
IF the LENGTH of the list X is GREATER THAN 2:
    ADD the list to list Z(contains matching elements)
    FOR EACH element of list Z:
        TRAVERSE vertically to find potential matches (L / T shaped)
        Do the same as previous in adding to list Z

IF no horizontal matches were found:
ITERATE vertically:
    Repeat the same operations above, except from vertical direction,             
    followed by further traversal for L and T shaped matches.
END OF ITERATIONS
IF matches were found:
    RETURN list X