Starting on a game state system

Author: Interrupt

game/game.zig

@@ -1,25 +1,28 @@
-pub const std = @import("std");
-pub const delve = @import("delve");
-pub const entities = @import("entities.zig");
-pub const basics = @import("../entities/basics.zig");
-pub const player = @import("../entities/player.zig");
-pub const inventory = @import("../entities/inventory.zig");
-pub const character = @import("../entities/character.zig");
-pub const box_collision = @import("../entities/box_collision.zig");
-pub const quakesolids = @import("../entities/quakesolids.zig");
-pub const mover = @import("../entities/mover.zig");
-pub const particles = @import("../entities/particle_emitter.zig");
-pub const options = @import("options.zig");
-pub const spinner = @import("../entities/spinner.zig");
-pub const stats = @import("../entities/actor_stats.zig");
-pub const weapons = @import("../entities/weapon.zig");
-pub const quakemap = @import("../entities/quakemap.zig");
-pub const string = @import("../utils/string.zig");
-pub const imgui = delve.imgui;
+const std = @import("std");
+const delve = @import("delve");
+const entities = @import("entities.zig");
+const game_states = @import("game_states.zig");
+const basics = @import("../entities/basics.zig");
+const player = @import("../entities/player.zig");
+const inventory = @import("../entities/inventory.zig");
+const character = @import("../entities/character.zig");
+const box_collision = @import("../entities/box_collision.zig");
+const quakesolids = @import("../entities/quakesolids.zig");
+const mover = @import("../entities/mover.zig");
+const particles = @import("../entities/particle_emitter.zig");
+const options = @import("options.zig");
+const spinner = @import("../entities/spinner.zig");
+const stats = @import("../entities/actor_stats.zig");
+const weapons = @import("../entities/weapon.zig");
+const quakemap = @import("../entities/quakemap.zig");
+const string = @import("../utils/string.zig");
+const title_screen = @import("states/title_screen.zig");
+const imgui = delve.imgui;
 
 pub const GameInstance = struct {
     allocator: std.mem.Allocator,
     world: *entities.World,
+    states: game_states.GameStateStack = .{},
 
     player_controller: ?*player.PlayerController = null,
     music: ?delve.platform.audio.Sound = null,
@@ -41,6 +44,8 @@ pub const GameInstance = struct {
         delve.debug.log("Game instance tearing down", .{});
         self.world.deinit();
 
+        self.states.deinit();
+
         // some components have globals that need to be cleaned up
         box_collision.deinit();
         particles.deinit();
@@ -90,6 +95,9 @@ pub const GameInstance = struct {
             .stream = true,
             .loop = true,
         });
+
+        const title_scr = try title_screen.TitleScreen.init();
+        self.states.setState(title_scr);
     }
 
     pub fn stop(self: *GameInstance) void {
@@ -103,6 +111,9 @@ pub const GameInstance = struct {
         self.world.tick(delta);
         self.time += @floatCast(delta);
 
+        // TODO: Testing game states
+        self.states.tick(delta);
+
         if (delve.platform.input.isKeyJustPressed(.K)) {
             self.saveGame("test_save_game.json") catch |e| {
                 delve.debug.warning("Could not write save game to json! {any}", .{e});

game/game_states.zig

@@ -0,0 +1,49 @@
+const std = @import("std");
+const delve = @import("delve");
+
+pub const GameState = struct {
+    impl_ptr: *anyopaque, // Pointer to the actual GameState struct
+    typename: []const u8,
+
+    // game state interface methods
+    _interface_tick: *const fn (self: *anyopaque, delta: f32) void,
+    _interface_deinit: *const fn (self: *anyopaque) void,
+
+    // _interface_draw: *const fn (self: *anyopaque) void,
+    // _nterface_physics_tick: *const fn (self: *anyopaque, delta: f32) void,
+    // _interface_deinit: *const fn (self: *anyopaque) void,
+
+    pub fn tick(self: *GameState, delta: f32) void {
+        self._interface_tick(self.impl_ptr, delta);
+    }
+
+    pub fn deinit(self: *GameState) void {
+        self._interface_deinit(self.impl_ptr);
+    }
+};
+
+/// A stack of game states, so that a pause screen could overlay a game for example
+pub const GameStateStack = struct {
+    current: ?GameState = null,
+
+    pub fn setState(self: *GameStateStack, new_state: GameState) void {
+        // deinit old state for now while we just have one
+        if (self.current) |*state| {
+            state.deinit();
+        }
+
+        self.current = new_state;
+    }
+
+    pub fn tick(self: *GameStateStack, delta: f32) void {
+        if (self.current) |*state| {
+            state.tick(delta);
+        }
+    }
+
+    pub fn deinit(self: *GameStateStack) void {
+        if (self.current) |*state| {
+            state.deinit();
+        }
+    }
+};

game/options.zig

@@ -1,4 +1,4 @@
-pub const std = @import("std");
+const std = @import("std");
 
 pub var options: Options = .{};
 

game/states/title_screen.zig

@@ -0,0 +1,41 @@
+const std = @import("std");
+const delve = @import("delve");
+const imgui = delve.imgui;
+const game_states = @import("../game_states.zig");
+
+pub const TitleScreen = struct {
+    pub fn init() !game_states.GameState {
+        const title_screen: *TitleScreen = try delve.mem.getAllocator().create(TitleScreen);
+        return .{
+            .impl_ptr = title_screen,
+            .typename = @typeName(@This()),
+            ._interface_tick = tick,
+            ._interface_deinit = deinit,
+        };
+    }
+
+    pub fn tick(self_impl: *anyopaque, delta: f32) void {
+        _ = self_impl;
+        _ = delta;
+
+        // delve.debug.log("Title screen tick!", .{});
+        //
+        const window_flags = imgui.ImGuiWindowFlags_NoTitleBar |
+            imgui.ImGuiWindowFlags_NoResize |
+            imgui.ImGuiWindowFlags_NoMove |
+            imgui.ImGuiWindowFlags_NoScrollbar |
+            imgui.ImGuiWindowFlags_NoSavedSettings |
+            imgui.ImGuiWindowFlags_NoInputs;
+
+        imgui.igSetNextWindowPos(.{ .x = 40, .y = 180 }, imgui.ImGuiCond_Once, .{ .x = 0, .y = 0 });
+        imgui.igSetNextWindowSize(.{ .x = 400, .y = 100 }, imgui.ImGuiCond_Once);
+        _ = imgui.igBegin("Title Screen Window", 0, window_flags);
+        imgui.igText("Super Boarding Party Title Screen");
+        imgui.igEnd();
+    }
+
+    pub fn deinit(self_impl: *anyopaque) void {
+        const self = @as(*TitleScreen, @ptrCast(self_impl));
+        delve.mem.getAllocator().destroy(self);
+    }
+};