Galactica/crates/content/src/gun.rs

use std::collections::HashMap;

use anyhow::{bail, Result};
use cgmath::Deg;

use crate::{Content, TextureHandle};

pub(super) mod syntax {
	use serde::Deserialize;
	// Raw serde syntax structs.
	// These are never seen by code outside this crate.

	#[derive(Debug, Deserialize)]
	pub struct Gun {
		pub projectile: Projectile,
		pub spread: f32,
		pub rate: f32,
		pub rate_rng: f32,
	}

	#[derive(Debug, Deserialize)]
	pub struct Projectile {
		pub sprite: String,
		pub size: f32,
		pub size_rng: f32,
		pub speed: f32,
		pub speed_rng: f32,
		pub lifetime: f32,
		pub lifetime_rng: f32,
		pub damage: f32,
	}
}

/// Represents a gun outfit.
#[derive(Debug, Clone)]
pub struct Gun {
	/// The name of this gun
	pub name: String,

	/// The projectile this gun produces
	pub projectile: Projectile,

	/// The accuracy of this gun.
	/// Projectiles can be off center up to
	/// `spread / 2` degrees in both directions.
	///
	/// (Forming a "fire cone" of `spread` degrees)
	pub spread: Deg<f32>,

	/// Average delay between projectiles, in seconds.
	pub rate: f32,

	/// Random variation of projectile delay, in seconds.
	/// Each shot waits (rate += rate_rng).
	pub rate_rng: f32,
}

/// Represents a projectile that a [`Gun`] produces.
#[derive(Debug, Clone)]
pub struct Projectile {
	/// The projectile sprite
	pub sprite: TextureHandle,

	/// The average size of this projectile
	/// (height in game units)
	pub size: f32,
	/// Random size variation
	pub size_rng: f32,

	/// The speed of this projectile, in game units / second
	pub speed: f32,
	/// Random speed variation
	pub speed_rng: f32,

	/// The lifespan of this projectile.
	/// It will vanish if it lives this long without hitting anything.
	pub lifetime: f32,
	/// Random lifetime variation
	pub lifetime_rng: f32,

	/// The damage this projectile does
	pub damage: f32,
}

impl super::Build for Gun {
	type InputSyntax = HashMap<String, syntax::Gun>;

	fn build(gun: Self::InputSyntax, ct: &mut Content) -> Result<()> {
		for (gun_name, gun) in gun {
			let th = match ct.texture_index.get(&gun.projectile.sprite) {
				None => bail!(
					"In gun `{}`: texture `{}` doesn't exist",
					gun_name,
					gun.projectile.sprite
				),
				Some(t) => *t,
			};

			ct.guns.push(Self {
				name: gun_name,
				spread: Deg(gun.spread),
				rate: gun.rate,
				rate_rng: gun.rate_rng,
				projectile: Projectile {
					sprite: th,
					size: gun.projectile.size,
					size_rng: gun.projectile.size_rng,
					speed: gun.projectile.speed,
					speed_rng: gun.projectile.speed_rng,
					lifetime: gun.projectile.lifetime,
					lifetime_rng: gun.projectile.lifetime_rng,
					damage: gun.projectile.damage,
				},
			});
		}

		return Ok(());
	}
}