Question 1

How do you implement collision detection in a Python Tetris game with OOP?

Accepted Answer

In this video I create a CollisionDetector class and treat collision as its own concern instead of mixing it into the Tile logic. Every time I move or rotate a tile, I check whether the updated coordinates would collide with the board borders or with the ground matrix. If there’s no collision, the move happens; if there is, I return a collision type (like left/right/bottom/ground/rotation) and block the action.

Question 2

How do you stop a Tetris piece from moving after it hits the ground in Python?

Accepted Answer

I add a lock concept: once a tile collides at the bottom (or with existing ground), it becomes locked. Then my drop logic merges that tile into the ground matrix and spawns a new random tile. I also lock rotation for consistency, so you can’t rotate a piece once it’s effectively placed.

Question 3

How do you represent Tetris pieces with matrices in Python?

Accepted Answer

My tiles are always represented as a 4x4 matrix, and the active pixels are stored as coordinates within that matrix. The Shape class tracks the rotation state and returns the matrix with the correct offset after movement. That makes it easier to render, rotate, and run collision checks consistently.

Question 4

How do you merge a falling tile into the board (ground) in Tetris?

Accepted Answer

I implement a Ground class as a matrix of zeros with the same width/height as the board, and when a tile locks I merge its occupied coordinates into that matrix. Then I render the board as essentially the max of the board matrix and the ground matrix, so placed tiles stay visible. This also sets me up to check collisions against already-placed blocks.

Question 5

How do you clear completed rows and cascade tiles down in Tetris?

Accepted Answer

I scan the ground matrix for rows that don’t contain any zeros, and when I find one I delete it and cascade everything above down. The cascade is basically a row reassignment step, and I had to be careful because my y reference increases downward. After clearing, I rebuild the coordinate list from the updated matrix so future collisions and rendering stay correct.

Question 6

Why does my Tetris collision detection break when rotating pieces near other blocks?

Accepted Answer

That’s exactly why I added a rotation collision type and passed translation/rotation context into the collision checks. If there’s no translation but the rotated coordinates overlap with ground coordinates, that’s a rotation collision and the rotation should be blocked. In my case, a lot of the debugging was making sure I wasn’t comparing against a stale matrix/coordinate list.

Question 7

How do you implement a score counter for cleared lines in Python Tetris?

Accepted Answer

I return a row_count from my ground row-expiration method and increment the score based on how many rows were deleted. I kept it simple: each cleared row increases the score by one. The important part is updating the ground state first, then updating the score so it reflects what actually happened.

CODE WITH ME | Python TETRIS Game OOP [PART 2]

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