yog_cli/design/
worldgen.rs

1//! The `.ydef` dimension designer's preview: its `terrain` generated by
2//! yog-worldgen — the code the runtime generates the game's chunks with —
3//! and drawn from above and in a slice.
4
5use yog_worldgen::{Generator, Terrain, preview};
6
7#[derive(yog_data::Schema)]
8pub struct Preview {
9    /// `size`×`size` blocks from above, `data:image/png;base64,…`.
10    top: String,
11    /// A slice down along x through the middle, `size` wide.
12    slice: String,
13    /// The slice's height, top and bottom.
14    slice_top: i32,
15    slice_bottom: i32,
16}
17
18fn png(pixels: &[u32], w: u32, h: u32) -> Result<String, String> {
19    let rgba: Vec<u8> = pixels
20        .iter()
21        .flat_map(|&p| [(p >> 16) as u8, (p >> 8) as u8, p as u8, (p >> 24) as u8])
22        .collect();
23    let mut out = Vec::new();
24    let mut enc = png::Encoder::new(&mut out, w, h);
25    enc.set_color(png::ColorType::Rgba);
26    enc.set_depth(png::BitDepth::Eight);
27    enc.set_compression(png::Compression::Fast);
28    let mut writer = enc.write_header().map_err(|e| e.to_string())?;
29    writer.write_image_data(&rgba).map_err(|e| e.to_string())?;
30    writer.finish().map_err(|e| e.to_string())?;
31    Ok(super::raster::png_url(&out))
32}
33
34/// The terrain of `text` (a `.ydef` of kind `dimension`) around 0, 0: `size` blocks across.
35pub fn render(text: &str, size: u32) -> Result<Preview, String> {
36    let size = size.clamp(16, 1024);
37    let def = yog_data::text::parse_value(text)
38        .map_err(|e| format!("{}:{}: {}", e.at.line, e.at.col, e.message))?;
39    let terrain = def
40        .get(yog_ids::dimension_field::TERRAIN)
41        .ok_or("no `terrain` — this dimension's chunks come from a generator in code")?;
42    let terrain = yog_data::read_value::<Terrain>(terrain).map_err(|ps| {
43        ps.iter()
44            .map(|p| format!("terrain.{}: {}", p.path, p.message))
45            .collect::<Vec<_>>()
46            .join("\n")
47    })?;
48    let int = |k: &str| {
49        def.get(yog_ids::dimension_field::DIMENSION_TYPE)
50            .and_then(|t| t.get(k))
51            .and_then(|v| v.as_i64())
52            .map(|v| v as i32)
53    };
54    let min_y = int("min_y").unwrap_or(-64);
55    let height = int("height").unwrap_or(384);
56    let g = Generator::new(terrain);
57    let half = size as i32 / 2;
58    let top = preview::top_down(
59        &g,
60        preview::Area {
61            x: -half,
62            z: -half,
63            w: size,
64            h: size,
65        },
66        min_y,
67    );
68    // The slice: from a little over the highest ground (or the fluid) down, 160 blocks at most.
69    let highest = (-half..half).map(|x| g.surface(x, 0)).max().unwrap_or(0);
70    let fluid = g.terrain.fluid.as_ref().map_or(i32::MIN, |f| f.level);
71    let slice_top = (highest.max(fluid) + 4).min(min_y + height - 1);
72    let slice_bottom = (slice_top - 160).max(min_y);
73    let rows = (slice_top - slice_bottom + 1) as u32;
74    let slice = preview::slice(
75        &g,
76        preview::Area {
77            x: -half,
78            z: 0,
79            w: size,
80            h: rows,
81        },
82        slice_top,
83        min_y,
84    );
85    Ok(Preview {
86        top: png(&top, size, size)?,
87        slice: png(&slice, size, (slice_top - slice_bottom + 1) as u32)?,
88        slice_top,
89        slice_bottom,
90    })
91}
92
93#[cfg(test)]
94mod tests {
95    #[test]
96    fn previews_a_dimensions_terrain() {
97        let text = r#"{ kind: "dimension", id: "hills", dimension_type: { min_y: 0, height: 256 },
98            terrain: { seed: 1, base_height: 64, noise: [{ scale: 50, amplitude: 12 }], fill: "@block:minecraft:stone",
99                fluid: { block: "@block:minecraft:water", level: 62 } } }"#;
100        let p = super::render(text, 32).unwrap();
101        assert!(
102            p.top.starts_with(super::super::raster::PNG_URL_PREFIX)
103                && p.slice.starts_with(super::super::raster::PNG_URL_PREFIX)
104        );
105        assert_eq!(p.slice_bottom, 0);
106        assert!(p.slice_top >= 66);
107        let e = super::render(r#"{ kind: "dimension", id: "x" }"#, 32)
108            .err()
109            .unwrap();
110        assert!(e.contains("no `terrain`"), "{e}");
111    }
112}
yog_cli/design/worldgen.rs

yog_cli/design/
worldgen.rs
