I’m developing a tile-based game. I encountered some unexpected behaviour in my collision code.
I don’t want to post the whole code here. Because it’s too long and might be painful to read (I am very sorry).

Basically, to detect and resolve collisions, I do this:

pseudocode:

// Resolve horizontal collisions
for tile in tiles:
    if checkCollision(tile.rect, player.rect):
        match tile.type:
            case Empty:
                continue

            case Platform, Wall:
                if player.velocity.x > 0.0:
                    intersect_rect = calculateIntersection(tile.rect, player.rect)
                    player.rect.x -= intersect_rect.width
                    player.velocity.x = 0.0

                elif player.velocity.x < 0.0:
                    intersect_rect = calculateIntersection(tile.rect, player.rect)
                    player.rect.x += intersect_rect.width
                    player.velocity.x = 0.0


// Resolve vertical collisions
for tile in tiles:
    if checkCollision(tile.rect, player.rect):
        match tile.type:
            case Empty:
                continue

            case Platform, Floor:
                if player.velocity.y > 0.0:
                    intersect_rect = calculateIntersection(tile.rect, player.rect)
                    player.rect.y = tile.rect.y - p.rect.height
                    player.velocity.y = 0.0

                elif player.velocity.y < 0.0:
                    intersect_rect = calculateIntersection(tile.rect, player.rect)
                    player.rect.y = tile.rect.y + tile.rect.height
                    player.velocity.y = 0.0

When I land on top of the platform, I got stuck a little bit, pressing A and D randomly teleport the player to the left side of the platform instantly.

I expect the player to be standing on top of the platform, but still move left and right normally.

I think the issue is the way I handle horizontal collisions, which makes the player’s x velocity become zero and therefore make the player stuck.
Also, I think when my player gets stuck and then I pressed A or D, it will actually push my player back or forward because of those lines: player.rect.x -= intersect_rect.width and player.rect.x += intersect_rect.width.

Also, thank you so much for taking time reading my question. This is making me confusing, because I tried adding different checks (only push the player up if he was falling, etc.) but nothing works. I appreciate all your response.