Question: How do you handle wall collision in GameMaker?

Answer

Handling wall collisions in GameMaker typically involves checking for potential overlaps between the player (or moving object) and solid objects (walls), and then resolving any detected collisions by adjusting the player's position to prevent the overlap. Below is a basic example of how this can be done using GML (GameMaker Language).

In your player object's step event, you would include collision-checking code:

// Get the player's intended movement
var moveX = speed * cos(direction);
var moveY = speed * sin(direction);

// Check horizontal collisions
if (place_meeting(x + moveX, y, obj_wall)) {
    // Resolve the collision horizontally by finding the nearest non-colliding x position
    while (!place_meeting(x + sign(moveX), y, obj_wall)) {
        x += sign(moveX);
    }
    moveX = 0;
}

// Move horizontally
x += moveX;

// Check vertical collisions
if (place_meeting(x, y + moveY, obj_wall)) {
    // Resolve the collision vertically by finding the nearest non-colliding y position
    while (!place_meeting(x, y + sign(moveY), obj_wall)) {
        y += sign(moveY);
    }
    moveY = 0;
}

// Move vertically
y += moveY;

In this code, obj_wall represents the object that has been designated as your solid wall. The functions cos() and sin() are used to calculate the movement along the x and y axis based on the speed and direction variables which you should define according to your game's mechanics.

The place_meeting() function checks if the player would collide with a wall at the new position (x+moveX, y for horizontal and x, y+moveY for vertical). If a collision is detected, we use a while loop and sign() function to move the player to the edge of the wall without overlapping it.

Please adjust the code above to match your specific needs such as variable names, movement calculations, and collision handling logic.