tetris-game | A simple Tetris game in OpenGL | Game Engine library

The function is really easy to understand. At first it loops through every child by using foreach, then it stores the child's rounded position in a variable. Afterwards it finds out if that position is inside the border, and then it finds out if there already is a block in the same grid entry or not.

In other words – every time a shape is moved or rotated, you have to check if that position was valid.

You do that by checking that the position of the shape is within the bounds and that the shape isn't intersecting with any other shapes.

If it is out of bounds or intersecting with other shapes you revert your last action.

Action: transform.Rotate(0, 0, -90);

Revert: transform.Rotate(0, 0, 90);