20 Game Challenge Game 1: Pong Part 2

I made good progress yesterday, and I caught myself going to Distractionland when I couldn’t immediately make sense of the collision and rigidbody weird bug. Luckily I noticed and came back, and I fixed it so I am not really stuck, I’m just on to the next part. Here are the updated checklists:

Learning goals for Pong:

• Using your game engine of choice!
• Creating and destroying objects.
• Processing player input and moving objects on screen.
• Detecting and reacting to collisions.

Requirements:

• Create an arena with two walls and a divider.
• Add a paddle on either end of the play field. Use player inputs to move the paddles up and down.
• Add a ball that moves around the playfield and bounces off of the paddles and walls.
• Detect when the ball leaves the playfield. Assign a point to the player who scored.
• Track and display the score for each player.

The part I got up to was making the ball move, so lets get back to it.

Kicking off the ball

I think what I want to do is apply a force to the ball at the start of the game? I actually did a bit of a test with it last night but it had to be every physics frame which didn’t feel right. I found apply_impulse(), which seems to be what I’m interested in based on this guide:

And it mostly works - it moves the ball. However, there is a problem: it pushes the paddle when it hits it.

The guide I mentioned earlier says that by default, a CharacterBody2D moved with move_and_collide() will not push any RigidBody2D it collides with. What? That is kinda strange and not what I’d expect. At least I know this now! If I use move_and_slide() it doesn’t move it quite as much, bit it still does and it shouldn’t at all.

I have decided to force it back to its position by storing the start x position and updating it to be that every frame.

Surely there is a better way but for now it works. And the ball is bouncing off the paddles, it kinda seems like the paddles have a bit of bouncy feedback now which is kinda cool.

Next problems: when the ball hits a top or bottom wall, it bounces perfectly vertically, meaning the game will never end, and the speed of the ball is really inconsistent.

Fixing the balls bounce off the top and bottom

At this point I will mention I added a physics material to the Ball RigidBody2d and added bounce. Otherwise it will continue to push the paddle:

I actually have a inkling that a Rigidbody2d will add these extra things I have to write, like fixing the speed, or fixing the angle of bounce. I want to try this with a Character2D before I try those. I found a suggestion from someone asking a question on reddit that seems like it may be what I need.

I’ll follow this tomorrow as it’s 10pm! Didn’t get too much time on it today but I want to do a bit by bit daily.