LibGdx Input Handling and Collision Detection

Question

I'm playing with libGdx, creating a simple platformer game. I'm using Tiled to create the map and the LibGdx tiledMap renderer. It's a similar setup to the SuperKoalio libgdx example.

My Collision detection at the moment, it just determining whether the player has hit a tile to the right of it, above it or below it. When it detects a collision to the right, it sets the players state to standing. Control of the player is done through the InputHandler. When the D key is pressed, it sets the players state to walking, when the key is released, it sets the state to standing.

My problem is, that if I'm holding down D, and I jump and hit a platform and stop, even when the player has dropped back down and should be able to continue moving, it won't, not until I release the D key and press it again. I can jump fine, but not walk.

Any ideas on why this is and how I can fix it? I've been staring at it for so long that I might be missing something obvious, in which case a fresh pair of eyes might help.

This is the code I've got right at the start of my player.update function to get the player moving.

if(state == State.Standing) {
        velocity.x = 0;
    } else if(state == State.Walking || state == State.Jumping) {
        velocity.x = MAX_VELOCITY;
    }

And this is an extract of the collision code :

for (Rectangle tile : tiles) {
        if (playerRect.overlaps(tile)) {                
            state = State.Standing;
            break;
        }
    }

Originally, the collision response set x velocity to 0, and the velocity was used to determine the state, which still produced the same problem.

Thanks

Collision detection is a pain if you're going to do it yourself. I think you need to handle the collision more appropriately instead of setting the player state to standing if he intersects any tile. You need to check how he is colliding with the tile before you determine if he is standing or not. — Barodapride
Thanks, I looked at what I was doing with the player states, and moved Jumping out of the enum, so you can be jumping and walking at the same time (in the air and moving right) and it seems to have solved it. Not sure if I fully understand why it now works, but it works and that's the main thing, :D — Cerberus90

Robert P Robert P · Accepted Answer · 2014-10-07T12:22:14

As your Collision-detection is allready working, the thing you need to change is the collision handling.
You set the Players state to Standing.
Instead of doing this you culd set a flag collision and in the update check this flag:

if(state == State.Standing || collision) {
    velocity.x = 0;
} else if(state == State.Walking || state == State.Jumping) {
    velocity.x = MAX_VELOCITY;
}

This way you know, if you don't move becuase you can't (collision==true) or if you don't move, because you don't press the key (state != State.Standing)
Of course you also need to know, when you don't collide anymore.
For this you could reset the collision flag after setting the velocity and recalculate it the next frame.

LibGdx Input Handling and Collision Detection

1 Answers