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Use grid size based arithmetics for offsets in hex tile layout #463

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Use grid size based arithmetics for offsets in hex tile layout #463

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67 changes: 17 additions & 50 deletions src/helpers/hex_grid/axial.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
//! Code for the axial coordinate system.

use crate::helpers::hex_grid::consts::{DOUBLE_INV_SQRT_3, HALF_SQRT_3, INV_SQRT_3};
use crate::helpers::hex_grid::cube::{CubePos, FractionalCubePos};
use crate::helpers::hex_grid::neighbors::{
HexColDirection, HexDirection, HexRowDirection, HEX_OFFSETS,
Expand All @@ -9,7 +8,7 @@ use crate::helpers::hex_grid::offset::{ColEvenPos, ColOddPos, RowEvenPos, RowOdd
use crate::map::HexCoordSystem;
use crate::tiles::TilePos;
use crate::{TilemapGridSize, TilemapSize};
use bevy::math::{Mat2, Vec2};
use bevy::math::Vec2;
use std::ops::{Add, Mul, Sub};

/// A position in a hex grid labelled according to [`HexCoordSystem::Row`] or
Expand Down Expand Up @@ -184,34 +183,6 @@ impl From<ColEvenPos> for AxialPos {
}
}

/// The matrix for mapping from [`AxialPos`], to world position when hexes are arranged
/// in row format ("pointy top" per Red Blob Games). See
/// [Size and Spacing](https://www.redblobgames.com/grids/hexagons/#size-and-spacing)
/// at Red Blob Games for an interactive visual explanation, but note that:
/// 1) we consider increasing-y to be the same as "going up", while RBG considers increasing-y to be "going down",
/// 2) our vectors have magnitude 1 (in order to allow for easy scaling based on grid-size)
pub const ROW_BASIS: Mat2 = Mat2::from_cols(Vec2::new(1.0, 0.0), Vec2::new(0.5, HALF_SQRT_3));

/// The inverse of [`ROW_BASIS`].
pub const INV_ROW_BASIS: Mat2 = Mat2::from_cols(
Vec2::new(1.0, 0.0),
Vec2::new(-1.0 * INV_SQRT_3, DOUBLE_INV_SQRT_3),
);

/// The matrix for mapping from [`AxialPos`], to world position when hexes are arranged
/// in column format ("flat top" per Red Blob Games). See
/// [Size and Spacing](https://www.redblobgames.com/grids/hexagons/#size-and-spacing)
/// at Red Blob Games for an interactive visual explanation, but note that:
/// 1) we consider increasing-y to be the same as "going up", while RBG considers increasing-y to be "going down",
/// 2) our vectors have magnitude 1 (in order to allow for easy scaling based on grid-size)
pub const COL_BASIS: Mat2 = Mat2::from_cols(Vec2::new(HALF_SQRT_3, 0.5), Vec2::new(0.0, 1.0));

/// The inverse of [`COL_BASIS`].
pub const INV_COL_BASIS: Mat2 = Mat2::from_cols(
Vec2::new(DOUBLE_INV_SQRT_3, -1.0 * INV_SQRT_3),
Vec2::new(0.0, 1.0),
);

pub const UNIT_Q: AxialPos = AxialPos { q: 1, r: 0 };

pub const UNIT_R: AxialPos = AxialPos { q: 0, r: -1 };
Expand All @@ -238,14 +209,17 @@ impl AxialPos {
(*self - *other).magnitude()
}

/// Project a vector representing a fractional axial position (i.e. the components can be `f32`)
/// into world space.
/// Project a vector, representing a fractional axial position (i.e. the components can be `f32`)
/// on a row-oriented grid ("pointy top"), into world space.
///
/// This is a helper function for [`center_in_world_row`](`Self::center_in_world_row`),
/// [`corner_offset_in_world_row`](`Self::corner_offset_in_world_row`) and
/// [`corner_in_world_row`](`Self::corner_in_world_row`).
#[inline]
pub fn project_row(axial_pos: Vec2, grid_size: &TilemapGridSize) -> Vec2 {
let unscaled_pos = ROW_BASIS * axial_pos;
Vec2::new(
grid_size.x * unscaled_pos.x,
ROW_BASIS.y_axis.y * grid_size.y * unscaled_pos.y,
grid_size.x * (axial_pos.x + axial_pos.y / 2.0),
grid_size.y * axial_pos.y * 0.75,
)
}

Expand Down Expand Up @@ -297,10 +271,9 @@ impl AxialPos {
/// [`corner_in_world_col`](`Self::corner_in_world_col`).
#[inline]
pub fn project_col(axial_pos: Vec2, grid_size: &TilemapGridSize) -> Vec2 {
let unscaled_pos = COL_BASIS * axial_pos;
Vec2::new(
COL_BASIS.x_axis.x * grid_size.x * unscaled_pos.x,
grid_size.y * unscaled_pos.y,
grid_size.x * axial_pos.x * 0.75,
grid_size.y * (axial_pos.y + axial_pos.x / 2.0),
)
}

Expand Down Expand Up @@ -350,12 +323,9 @@ impl AxialPos {
/// * The world position corresponding to `[0.0, 0.0]` lies on the hex grid at index `(0, 0)`.
#[inline]
pub fn from_world_pos_row(world_pos: &Vec2, grid_size: &TilemapGridSize) -> AxialPos {
let normalized_world_pos = Vec2::new(
world_pos.x / grid_size.x,
world_pos.y / (ROW_BASIS.y_axis.y * grid_size.y),
);
let frac_pos = FractionalAxialPos::from(INV_ROW_BASIS * normalized_world_pos);
frac_pos.round()
let r = world_pos.y * 4.0 / grid_size.y / 3.0;
let q = world_pos.x / grid_size.x - r / 2.0;
FractionalAxialPos { q, r }.round()
}

/// Returns the axial position of the hex grid containing the given world position, assuming that:
Expand All @@ -364,12 +334,9 @@ impl AxialPos {
/// * The world position corresponding to `[0.0, 0.0]` lies on the hex grid at index `(0, 0)`.
#[inline]
pub fn from_world_pos_col(world_pos: &Vec2, grid_size: &TilemapGridSize) -> AxialPos {
let normalized_world_pos = Vec2::new(
world_pos.x / (COL_BASIS.x_axis.x * grid_size.x),
world_pos.y / grid_size.y,
);
let frac_pos = FractionalAxialPos::from(INV_COL_BASIS * normalized_world_pos);
frac_pos.round()
let q = world_pos.x * 4.0 / grid_size.x / 3.0;
let r = world_pos.y / grid_size.y - q / 2.0;
FractionalAxialPos { q, r }.round()
}

/// Try converting into a [`TilePos`].
Expand Down
13 changes: 0 additions & 13 deletions src/helpers/hex_grid/consts.rs
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1 change: 0 additions & 1 deletion src/helpers/hex_grid/mod.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,4 @@
pub mod axial;
pub mod consts;
pub mod cube;
pub mod neighbors;
pub mod offset;
8 changes: 1 addition & 7 deletions src/render/shaders/column_even_hex.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,7 @@

// Gets the screen space coordinates of the bottom left of an isometric tile position.
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Not related to this PR, but all the comments seem to be copy and paste... Haha.

fn hex_col_tile_pos_to_world_pos(pos: vec2<f32>, grid_width: f32, grid_height: f32) -> vec2<f32> {
let SQRT_3: f32 = 1.7320508;
let HALF_SQRT_3: f32 = 0.8660254;
let COL_BASIS_X: vec2<f32> = vec2<f32>(HALF_SQRT_3, 0.5);
let COL_BASIS_Y: vec2<f32> = vec2<f32>(0.0, 1.0);

let unscaled_pos = pos.x * COL_BASIS_X + pos.y * COL_BASIS_Y;
return vec2<f32>(COL_BASIS_X.x * grid_width * unscaled_pos.x, grid_height * unscaled_pos.y);
return vec2<f32>(grid_width * pos.x * 0.75, grid_height * (pos.y + pos.x / 2.0));
}

fn col_even_to_axial(offset_pos: vec2<f32>) -> vec2<f32> {
Expand Down
8 changes: 1 addition & 7 deletions src/render/shaders/column_hex.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,7 @@

// Gets the screen space coordinates of the bottom left of an isometric tile position.
fn hex_col_tile_pos_to_world_pos(pos: vec2<f32>, grid_width: f32, grid_height: f32) -> vec2<f32> {
let SQRT_3: f32 = 1.7320508;
let HALF_SQRT_3: f32 = 0.8660254;
let COL_BASIS_X: vec2<f32> = vec2<f32>(HALF_SQRT_3, 0.5);
let COL_BASIS_Y: vec2<f32> = vec2<f32>(0.0, 1.0);

let unscaled_pos = pos.x * COL_BASIS_X + pos.y * COL_BASIS_Y;
return vec2<f32>(COL_BASIS_X.x * grid_width * unscaled_pos.x, grid_height * unscaled_pos.y);
return vec2<f32>(grid_width * pos.x * 0.75, grid_height * (pos.y + pos.x / 2.0));
}

fn get_mesh(v_index: u32, vertex_position: vec3<f32>) -> MeshOutput {
Expand Down
8 changes: 1 addition & 7 deletions src/render/shaders/column_odd_hex.wgsl
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Expand Up @@ -6,13 +6,7 @@

// Gets the screen space coordinates of the bottom left of an isometric tile position.
fn hex_col_tile_pos_to_world_pos(pos: vec2<f32>, grid_width: f32, grid_height: f32) -> vec2<f32> {
let SQRT_3: f32 = 1.7320508;
let HALF_SQRT_3: f32 = 0.8660254;
let COL_BASIS_X: vec2<f32> = vec2<f32>(HALF_SQRT_3, 0.5);
let COL_BASIS_Y: vec2<f32> = vec2<f32>(0.0, 1.0);

let unscaled_pos = pos.x * COL_BASIS_X + pos.y * COL_BASIS_Y;
return vec2<f32>(COL_BASIS_X.x * grid_width * unscaled_pos.x, grid_height * unscaled_pos.y);
return vec2<f32>(grid_width * pos.x * 0.75, grid_height * (pos.y + pos.x / 2.0));
}

fn col_even_to_axial(offset_pos: vec2<f32>) -> vec2<f32> {
Expand Down
8 changes: 1 addition & 7 deletions src/render/shaders/row_even_hex.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,7 @@

// Gets the screen space coordinates of the bottom left of an isometric tile position.
fn hex_row_tile_pos_to_world_pos(pos: vec2<f32>, grid_width: f32, grid_height: f32) -> vec2<f32> {
let SQRT_3: f32 = 1.7320508;
let HALF_SQRT_3: f32 = 0.8660254;
let ROW_BASIS_X: vec2<f32> = vec2<f32>(1.0, 0.0);
let ROW_BASIS_Y: vec2<f32> = vec2<f32>(0.5, HALF_SQRT_3);

let unscaled_pos = pos.x * ROW_BASIS_X + pos.y * ROW_BASIS_Y;
return vec2<f32>(grid_width * unscaled_pos.x, ROW_BASIS_Y.y * grid_height * unscaled_pos.y);
return vec2<f32>(grid_width * (pos.x + pos.y / 2.0), grid_height * pos.y * 0.75);
}

fn row_even_to_axial(offset_pos: vec2<f32>) -> vec2<f32> {
Expand Down
8 changes: 1 addition & 7 deletions src/render/shaders/row_hex.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,7 @@

// Gets the screen space coordinates of the bottom left of an isometric tile position.
fn hex_row_tile_pos_to_world_pos(pos: vec2<f32>, grid_width: f32, grid_height: f32) -> vec2<f32> {
let SQRT_3: f32 = 1.7320508;
let HALF_SQRT_3: f32 = 0.8660254;
let ROW_BASIS_X: vec2<f32> = vec2<f32>(1.0, 0.0);
let ROW_BASIS_Y: vec2<f32> = vec2<f32>(0.5, HALF_SQRT_3);

let unscaled_pos = pos.x * ROW_BASIS_X + pos.y * ROW_BASIS_Y;
return vec2<f32>(grid_width * unscaled_pos.x, ROW_BASIS_Y.y * grid_height * unscaled_pos.y);
return vec2<f32>(grid_width * (pos.x + pos.y / 2.0), grid_height * pos.y * 0.75);
}

fn get_mesh(v_index: u32, vertex_position: vec3<f32>) -> MeshOutput {
Expand Down
8 changes: 1 addition & 7 deletions src/render/shaders/row_odd_hex.wgsl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,13 +5,7 @@

// Gets the screen space coordinates of the bottom left of an isometric tile position.
fn hex_row_tile_pos_to_world_pos(pos: vec2<f32>, grid_width: f32, grid_height: f32) -> vec2<f32> {
let SQRT_3: f32 = 1.7320508;
let HALF_SQRT_3: f32 = 0.8660254;
let ROW_BASIS_X: vec2<f32> = vec2<f32>(1.0, 0.0);
let ROW_BASIS_Y: vec2<f32> = vec2<f32>(0.5, HALF_SQRT_3);

let unscaled_pos = pos.x * ROW_BASIS_X + pos.y * ROW_BASIS_Y;
return vec2<f32>(grid_width * unscaled_pos.x, ROW_BASIS_Y.y * grid_height * unscaled_pos.y);
return vec2<f32>(grid_width * (pos.x + pos.y / 2.0), grid_height * pos.y * 0.75);
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I think naming these in variables as before would help, e.g.

Suggested change
return vec2<f32>(grid_width * (pos.x + pos.y / 2.0), grid_height * pos.y * 0.75);
let ROW_BASIS_X: f32 = 0.5;
let ROW_BASIS_Y: f32 = 0.75;
return vec2<f32>(grid_width * (pos.x + pos.y * ROW_BASIS_X), grid_height * pos.y * ROW_BASIS_Y);

}

fn row_odd_to_axial(offset_pos: vec2<f32>) -> vec2<f32> {
Expand Down