如何在二维网格中的固定值之间进行插值以生成生物群落？

Question

我目前正在我的游戏中实现生物群落生成，我想使生物群落的类型依赖于humidity和temperature值，这些值是由逐渐产生的噪音产生的。

不同的生物群体应该有不同的高度，如果不进行插值，就会像预期的那样在生物群落边界上产生突然的高度差异。

我尝试的是在网格中得到两个相邻的生物群落，并测量每个生物群落的混合百分比。

稍后，我从生物群落中得到3个不同的height值，并将每个值与各自的blend值相乘。

下面是简化和剥离的代码，用于获取生物群落：

const BIOME_GRID_SIZE: usize = 2;
const BIOME_INDEX_SIZE: usize = BIOME_GRID_SIZE - 1;
const BIOME_GRID: [[Biomes; BIOME_GRID_SIZE]; BIOME_GRID_SIZE] =
    [
        [Biomes::Mountains, Biomes::Forest],
        [Biomes::Desert   , Biomes::Mesa  ],
    ];

fn get_height(coord: [i64; 2], noise: &Noise) -> i64 {
    let temperature = (noise.get_2d(coord) + 0.5).clamp(0.0, 1.0);
    let humidity = (noise.get_2d(coord /* + some offset */) + 0.5).clamp(0.0, 1.0);

    let x = BIOME_GRID_SIZE as f64 * humidity;
    let y = BIOME_GRID_SIZE as f64 * temperature;

    let x_frac = (x.fract() - 0.5) * 2.0;
    let y_frac = (y.fract() - 0.5) * 2.0;
    let x_blending = x_frac.abs();
    let y_blending = y_frac.abs();
    let own_blending = 2.0 - x_blending - y_blending;

    // direction of neighbour biomes
    let x_direction = x_frac.signum() as isize;
    let y_direction = y_frac.signum() as isize;

    let x_index = (x.trunc() as isize).clamp(0, BIOME_INDEX_SIZE as isize);
    let y_index = (y.trunc() as isize).clamp(0, BIOME_INDEX_SIZE as isize);
    let biomes = get_biomes(x_index, y_index, x_direction, y_direction);

    blend(
        coord,
        noise,
        biomes,
        [
            own_blending,
            x_blending,
            y_blending,
        ]
    ),
}

// get main and neighbour biomes
fn get_biomes(x: isize, y: isize, x_direction: isize, y_direction: isize) -> [Biomes; 3] {
    let mut biomes = [Biomes::Ocean; 3];

    for (i, (d_x, d_y)) in [(0, 0), (x_direction, 0), (0, y_direction)].iter().enumerate() {
        let x_index = (x + d_x).clamp(0, BIOME_INDEX_SIZE as isize) as usize;
        let y_index = (y + d_y).clamp(0, BIOME_INDEX_SIZE as isize) as usize;
        let biome = BIOME_GRID[x_index][y_index];
        biomes[i] = biome;
    }

    biomes
}

pub fn blend(
    coord: [i64; 2],
    noise: &Noise,
    biomes: [Biomes; 4],
    blending: [f64; 4],
) -> i64 {
    let heights: Vec<f64> = biomes
        .iter()
        .map(|x| x.get().height(coord, noise) as f64)
        .collect();

    let height = heights[0] * blending[0] + heights[1] * blending[1] + heights[2] * blending[2];
    let height = height as i64;

    height
}

这在某些情况下很好，而在另一些情况下则完全失败。

我不确定，两个邻居是否足够，以及如何正确地获得blend值。

这个问题有更好的解决办法吗？

Answer 1

一般来说，对于双线性混合，您将使用四点。如果我正确理解你的代码，那就是每个生物群落的四幅高度图。然后，您通过一个轴(例如湿度)的两个对与另一个轴，然后将这两个混合值再次与另一个轴(例如温度)。