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use fxhash::hash32;
use glam::IVec2;
use crate::proc_gen::tileset_loader::TileOrientation;
const SEED: u32 = 100000;
pub fn split_position(pixel: IVec2, short: i32) -> (IVec2, IVec2, TileOrientation) {
let grid = pixel.div_euclid(IVec2::splat(short));
let local = pixel.rem_euclid(IVec2::splat(short));
match (grid.x - grid.y).rem_euclid(4) {
0 => (grid, local, TileOrientation::Horizontal),
1 => (
grid - IVec2::X,
local + IVec2::new(short, 0),
TileOrientation::Horizontal,
),
3 => (grid, local, TileOrientation::Vertical),
2 => (
grid - IVec2::Y,
local + IVec2::new(0, short),
TileOrientation::Vertical,
),
_ => unreachable!(),
}
}
// better "%" for hashes since it prefers the high bits
#[inline]
fn reduce(h: u32, n: usize) -> usize {
(((h as u128) * (n as u128)) >> 32) as usize
}
pub fn variant_index(grid: IVec2, variants: usize) -> usize {
reduce(hash32(&(grid, SEED)), variants)
}
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