add shooting

src/game.zig

@@ -33,6 +33,13 @@ const Player = struct {
     pos: Vec2 = .zero,
     vel: Vec2 = .zero,
     acc: Vec2 = .zero,
+    last_shot_at: ?Nanoseconds = null
+};
+
+const Bullet = struct {
+    pos: Vec2 = .zero,
+    vel: Vec2 = .zero,
+    size: f32 = 5
 };
 
 arena: std.heap.ArenaAllocator,
@@ -41,6 +48,7 @@ rng: RNGState,
 assets: *Assets,
 
 player: Player = .{},
+bullets: std.ArrayList(Bullet) = .empty,
 
 pub fn init(gpa: Allocator, seed: u64, assets: *Assets) !Game {
     var arena = std.heap.ArenaAllocator.init(gpa);
@@ -59,6 +67,7 @@ pub fn init(gpa: Allocator, seed: u64, assets: *Assets) !Game {
 
 pub fn deinit(self: *Game) void {
     self.arena.deinit();
+    self.bullets.deinit(self.gpa);
 }
 
 pub fn tick(self: *Game, frame: *Engine.Frame) !void {
@@ -106,6 +115,33 @@ pub fn tick(self: *Game, frame: *Engine.Frame) !void {
     self.player.vel = self.player.vel.multiplyScalar(friction_force);
     self.player.pos = self.player.pos.add(self.player.vel.multiplyScalar(dt));
 
+    if (frame.input.mouse_position) |mouse| {
+        const cursor_size = Vec2.init(10, 10);
+        frame.drawRectangle(.{
+            .rect = .{
+                .pos = mouse.sub(cursor_size.divideScalar(2)),
+                .size = cursor_size,
+            },
+            .color = rgba(255, 200, 200, 0.5)
+        });
+
+        const bullet_dir = mouse.sub(self.player.pos).normalized();
+
+        var cooldown_complete = true;
+        if (self.player.last_shot_at) |last_shot_at| {
+            const cooldown_ns = std.time.ns_per_ms * 500;
+            cooldown_complete = frame.time_ns > last_shot_at + cooldown_ns;
+        }
+
+        if (frame.isMouseDown(.left) and cooldown_complete) {
+            self.player.last_shot_at = frame.time_ns;
+            try self.bullets.append(self.gpa, .{
+                .pos = self.player.pos,
+                .vel = bullet_dir.multiplyScalar(50)
+            });
+        }
+    }
+
     var size = self.assets.players_tilemap.tile_size;
     frame.drawRectangle(.{
         .rect = .{
@@ -114,6 +150,18 @@ pub fn tick(self: *Game, frame: *Engine.Frame) !void {
         },
         .color = rgb(255, 255, 255)
     });
+
+    for (self.bullets.items) |*bullet| {
+        bullet.pos = bullet.pos.add(bullet.vel.multiplyScalar(dt));
+
+        frame.drawRectangle(.{
+            .rect = .{
+                .pos = bullet.pos.sub(.init(bullet.size, bullet.size)),
+                .size = .init(bullet.size, bullet.size),
+            },
+            .color = rgb(200, 20, 255)
+        });
+    }
 }
 
 pub fn debug(self: *Game) !void {