libgm 0.5.0

A tool for modding, unpacking and decompiling GameMaker games
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221

use macros::named_list_chunk;

use crate::prelude::*;
use crate::util::init::vec_with_capacity;
use crate::wad::deserialize::reader::DataReader;
use crate::wad::elements::GMElement;
use crate::wad::elements::texture_page_item::GMTexturePageItem;
use crate::wad::reference::GMRef;
use crate::wad::serialize::builder::DataBuilder;

const ALIGNMENT: u32 = 8;

/// See [`GMBackground`].
#[named_list_chunk("BGND")]
pub struct GMBackgrounds {
    pub backgrounds: Vec<GMBackground>,
    pub exists: bool,
}

impl GMElement for GMBackgrounds {
    fn deserialize(reader: &mut DataReader) -> Result<Self> {
        let mut is_aligned: bool = true;
        let backgrounds: Vec<GMBackground> =
            reader.read_aligned_list_chunk(ALIGNMENT, &mut is_aligned)?;
        Ok(Self { backgrounds, exists: true })
    }

    fn serialize(&self, builder: &mut DataBuilder) -> Result<()> {
        builder.write_pointer_list(&self.backgrounds)?;
        Ok(())
    }
}

/// A background or tileset entry in a data file.
/// ___
/// For GameMaker Studio 2, this will only ever be a tileset.
/// For GameMaker Studio 1, this is usually a background,
/// but is sometimes repurposed as use for a tileset as well.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GMBackground {
    /// The name of the background.
    pub name: String,
    /// Whether the background should be transparent.
    pub transparent: bool,
    /// Whether the background should get smoothed.
    pub smooth: bool,
    /// Whether to preload the background.
    pub preload: bool,
    /// The [`GMTexturePageItem`] this background uses.
    pub texture: Option<GMRef<GMTexturePageItem>>,
    /// Only set in GMS 2.0+.
    pub gms2_data: Option<GMS2Data>,
}

impl GMElement for GMBackground {
    fn deserialize(reader: &mut DataReader) -> Result<Self> {
        let name: String = reader.read_gm_string()?;
        let transparent = reader.read_bool32()?;
        let smooth = reader.read_bool32()?;
        let preload = reader.read_bool32()?;
        let texture: Option<GMRef<GMTexturePageItem>> = reader.read_gm_texture_opt()?;
        let gms2_data: Option<GMS2Data> = reader.deserialize_if_gm_version((2, 0))?;

        Ok(Self {
            name,
            transparent,
            smooth,
            preload,
            texture,
            gms2_data,
        })
    }

    fn serialize(&self, builder: &mut DataBuilder) -> Result<()> {
        builder.write_gm_string(&self.name);
        builder.write_bool32(self.transparent);
        builder.write_bool32(self.smooth);
        builder.write_bool32(self.preload);
        builder.write_gm_texture_opt(self.texture)?;
        builder.write_if_ver(&self.gms2_data, "GMS2 data", (2, 0))?;
        Ok(())
    }

    fn serialize_pre_padding(&self, builder: &mut DataBuilder) -> Result<()> {
        builder.align(ALIGNMENT);
        Ok(())
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct GMS2Data {
    /// The width of a tile in this tileset.
    pub tile_width: u32,

    /// The height of a tile in this tileset.
    pub tile_height: u32,

    /// GM 2024.14.1+ only.
    pub tile_separation_x: u32,

    /// GM 2024.14.1+ only.
    pub tile_separation_y: u32,

    /// The amount of extra empty pixels left and right a tile in this tileset.
    pub output_border_x: u32,

    /// The amount of extra empty pixels above and below a tile in this tileset.
    pub output_border_y: u32,

    /// The amount of columns this tileset has.
    pub tile_columns: u32,

    /// The number of frames of the tileset animation.
    pub items_per_tile_count: u32,

    /// Exported sprite index, if the background's corresponding sprite was
    /// marked to still be exported. Will be either 0 or -1 (depending on GM
    /// version) when the sprite is not exported, which makes this a bit
    /// ambiguous.
    ///
    /// In newer versions (2024.13), this seems to be used? see <https://github.com/BioTomateDE/LibGM/issues/5>
    pub exported_sprite_index: u32,

    /// The time for each frame in microseconds.
    pub frame_length: i64,

    /// All tile ids of this tileset.
    pub tile_ids: Vec<u32>,
}

impl GMElement for GMS2Data {
    fn deserialize(reader: &mut DataReader) -> Result<Self> {
        let unknown_always_two = reader.read_u32()?;
        reader.assert_int(unknown_always_two, 2, "Unknown Always Two")?;

        let tile_width = reader.read_u32()?;
        let tile_height = reader.read_u32()?;

        let mut tile_separation_x = 0;
        let mut tile_separation_y = 0;
        if reader.general_info.is_version_at_least((2024, 14, 1)) {
            tile_separation_x = reader.read_u32()?;
            tile_separation_y = reader.read_u32()?;
        }

        let output_border_x = reader.read_u32()?;
        let output_border_y = reader.read_u32()?;
        let tile_columns = reader.read_u32()?;

        let items_per_tile_count = reader.read_u32()?;
        if items_per_tile_count == 0 {
            bail!("Items per tile count cannot be zero");
        }

        let tile_count = reader.read_u32()?;
        let exported_sprite_index = reader.read_u32()?;
        let frame_length = reader.read_i64()?;

        let total_tile_count = tile_count
            .checked_mul(items_per_tile_count)
            .ok_or("Total Tile count multiplication overflowed")?;

        let mut tile_ids: Vec<u32> = vec_with_capacity(total_tile_count)?;
        for _ in 0..total_tile_count {
            tile_ids.push(reader.read_u32()?);
        }

        Ok(Self {
            tile_width,
            tile_height,
            tile_separation_x,
            tile_separation_y,
            output_border_x,
            output_border_y,
            tile_columns,
            items_per_tile_count,
            exported_sprite_index,
            frame_length,
            tile_ids,
        })
    }

    fn serialize(&self, builder: &mut DataBuilder) -> Result<()> {
        builder.write_u32(2); // UnknownAlwaysTwo
        builder.write_u32(self.tile_width);
        builder.write_u32(self.tile_height);

        if builder.is_version_at_least((2024, 14, 1)) {
            builder.write_u32(self.tile_separation_x);
            builder.write_u32(self.tile_separation_y);
        }

        builder.write_u32(self.output_border_x);
        builder.write_u32(self.output_border_y);
        builder.write_u32(self.tile_columns);

        let total_tile_count: usize = self.tile_ids.len();
        let items_per_tile = self.items_per_tile_count as usize;

        if !total_tile_count.is_multiple_of(items_per_tile) {
            bail!(
                "Background Tiles do not add up: {} total tiles, {} items per tile leaves a \
                 remainder of {}",
                total_tile_count,
                items_per_tile,
                total_tile_count % items_per_tile,
            );
        }

        let tile_count: usize = total_tile_count / items_per_tile;
        builder.write_usize(items_per_tile)?;
        builder.write_usize(tile_count)?;

        builder.write_u32(0); // UnknownAlwaysZero
        builder.write_i64(self.frame_length);
        for tile_id in &self.tile_ids {
            builder.write_u32(*tile_id);
        }
        Ok(())
    }
}