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 base64::Engine;
6use yog_worldgen::{Generator, Terrain, preview};
7
8#[derive(serde::Serialize)]
9pub struct Preview {
10    /// `size`×`size` blocks from above, `data:image/png;base64,…`.
11    top: String,
12    /// A slice down along x through the middle, `size` wide.
13    slice: String,
14    /// The slice's height, top and bottom.
15    slice_top: i32,
16    slice_bottom: i32,
17}
18
19fn png(pixels: &[u32], w: u32, h: u32) -> Result<String, String> {
20    let rgba: Vec<u8> = pixels.iter().flat_map(|&p| [(p >> 16) as u8, (p >> 8) as u8, p as u8, (p >> 24) as u8]).collect();
21    let mut out = Vec::new();
22    let mut enc = png::Encoder::new(&mut out, w, h);
23    enc.set_color(png::ColorType::Rgba);
24    enc.set_depth(png::BitDepth::Eight);
25    enc.set_compression(png::Compression::Fast);
26    let mut writer = enc.write_header().map_err(|e| e.to_string())?;
27    writer.write_image_data(&rgba).map_err(|e| e.to_string())?;
28    writer.finish().map_err(|e| e.to_string())?;
29    Ok(format!("data:image/png;base64,{}", base64::engine::general_purpose::STANDARD.encode(out)))
30}
31
32/// The terrain of `text` (a `.ydef` of kind `dimension`) around 0, 0: `size` blocks across.
33pub fn render(text: &str, size: u32) -> Result<Preview, String> {
34    let size = size.clamp(16, 1024);
35    let def = yog_data::text::parse_value(text).map_err(|e| format!("{}:{}: {}", e.at.line, e.at.col, e.message))?;
36    let terrain = def.get("terrain").ok_or("no `terrain` — this dimension's chunks come from a generator in code")?;
37    let terrain = yog_data::read_value::<Terrain>(terrain).map_err(|ps| {
38        ps.iter().map(|p| format!("terrain.{}: {}", p.path, p.message)).collect::<Vec<_>>().join("\n")
39    })?;
40    let int = |k: &str| def.get("dimension_type").and_then(|t| t.get(k)).and_then(|v| v.as_i64()).map(|v| v as i32);
41    let min_y = int("min_y").unwrap_or(-64);
42    let height = int("height").unwrap_or(384);
43    let g = Generator::new(terrain);
44    let half = size as i32 / 2;
45    let top = preview::top_down(&g, -half, -half, size, size, min_y);
46    // The slice: from a little over the highest ground (or the fluid) down, 160 blocks at most.
47    let highest = (-half..half).map(|x| g.surface(x, 0)).max().unwrap_or(0);
48    let fluid = g.terrain.fluid.as_ref().map_or(i32::MIN, |f| f.level);
49    let slice_top = (highest.max(fluid) + 4).min(min_y + height - 1);
50    let slice_bottom = (slice_top - 160).max(min_y);
51    let slice = preview::slice(&g, -half, 0, size, slice_top, slice_bottom, min_y);
52    Ok(Preview {
53        top: png(&top, size, size)?,
54        slice: png(&slice, size, (slice_top - slice_bottom + 1) as u32)?,
55        slice_top,
56        slice_bottom,
57    })
58}
59
60#[cfg(test)]
61mod tests {
62    #[test]
63    fn previews_a_dimensions_terrain() {
64        let text = r#"{ kind: "dimension", id: "hills", dimension_type: { min_y: 0, height: 256 },
65            terrain: { seed: 1, base_height: 64, noise: [{ scale: 50, amplitude: 12 }], fill: "@block:minecraft:stone",
66                fluid: { block: "@block:minecraft:water", level: 62 } } }"#;
67        let p = super::render(text, 32).unwrap();
68        assert!(p.top.starts_with("data:image/png;base64,") && p.slice.starts_with("data:image/png;base64,"));
69        assert_eq!(p.slice_bottom, 0);
70        assert!(p.slice_top >= 66);
71        let e = super::render(r#"{ kind: "dimension", id: "x" }"#, 32).err().unwrap();
72        assert!(e.contains("no `terrain`"), "{e}");
73    }
74}
yog_cli/design/worldgen.rs

yog_cli/design/
worldgen.rs
