Building Pong in Zig with raylib (part 1 – paddles and a ball)

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I looked over this PR, and also tried building/running the code on my machine for the first time. If you haven’t tested it on Windows yet, I can confirm that it runs great!

My feedback:

  • std.heap.GeneralPurposeAllocator is deprecated, use std.heap.DebugAllocator (it’s basically the same thing under a different name).
  • You are initializing the allocator correctly, nothing to change there.
  • The proper way to deinit your allocator is to just do defer _ = gpa.deinit(). deinit will already print memory leak info if any leaks occur, so there is no need to @panic if leaks occur.
  • The showScore logic could be part of Paddle since the paddles own the scores, but that feels kinds unintuitive. I think that if you want a super ‘correct’ structure/hierarchy, you should either move the scores into the Game struct and keep showScore in Game, or make a new Player struct that contains a score, a paddle, and showScore. Either way, moving the score out of Paddle seems like the right call.
  • Your score rendering is fine, but just in case you want to make the font larger, I wrote an example of how you could do that in your code. I wanted to point this out because setting font sizes in dvui is a little unintuitive, and I wasn’t sure if you were happy with the font size, or if you just settled for the largest default option:
const font_size: f32 = 64;
var label_options: dvui.Options = .{
    .color_text = .white,
    .font_style = .title,
};
label_options.font = label_options.fontGet().resize(font_size);
dvui.label(@src(), "{d}", .{score}, label_options);
  • A ball may still be colliding with a paddle after bouncing off it, triggering an additional bounce. This can lead to a glitchy state where the ball is permanently colliding, constantly switching direction while embedded in the paddle. You can resolve this by making your crossing_x logic check if the ball is moving towards the paddle:
const crossing_x = switch (self.which) {
    .right => ball.vel.x > 0 and
        ball.pos.x + ball.r >= self.pos.x,
    .left => ball.vel.x < 0 and
        ball.pos.x - ball.r <= self.pos.x + size.x,
};
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