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use bevy_math::{primitives::Plane3d, Dir3, Quat, Vec2, Vec3};
use wgpu::PrimitiveTopology;
use crate::{
mesh::{Indices, Mesh, MeshBuilder, Meshable},
render_asset::RenderAssetUsages,
};
/// A builder used for creating a [`Mesh`] with a [`Plane3d`] shape.
#[derive(Clone, Copy, Debug, Default)]
pub struct PlaneMeshBuilder {
/// The [`Plane3d`] shape.
pub plane: Plane3d,
/// The number of subdivisions in the mesh.
///
/// 0 - is the original plane geometry, the 4 points in the XZ plane.
///
/// 1 - is split by 1 line in the middle of the plane on both the X axis and the Z axis, resulting in a plane with 4 quads / 8 triangles.
///
/// 2 - is a plane split by 2 lines on both the X and Z axes, subdividing the plane into 3 equal sections along each axis, resulting in a plane with 9 quads / 18 triangles.
///
/// and so on...
pub subdivisions: u32,
}
impl PlaneMeshBuilder {
/// Creates a new [`PlaneMeshBuilder`] from a given normal and size.
#[inline]
pub fn new(normal: Dir3, size: Vec2) -> Self {
Self {
plane: Plane3d {
normal,
half_size: size / 2.0,
},
subdivisions: 0,
}
}
/// Creates a new [`PlaneMeshBuilder`] from the given size, with the normal pointing upwards.
#[inline]
pub fn from_size(size: Vec2) -> Self {
Self {
plane: Plane3d {
half_size: size / 2.0,
..Default::default()
},
subdivisions: 0,
}
}
/// Creates a new [`PlaneMeshBuilder`] from the given length, with the normal pointing upwards,
/// and the resulting [`PlaneMeshBuilder`] being a square.
#[inline]
pub fn from_length(length: f32) -> Self {
Self {
plane: Plane3d {
half_size: Vec2::splat(length) / 2.0,
..Default::default()
},
subdivisions: 0,
}
}
/// Sets the normal of the plane, aka the direction the plane is facing.
#[inline]
#[doc(alias = "facing")]
pub fn normal(mut self, normal: Dir3) -> Self {
self.plane = Plane3d {
normal,
..self.plane
};
self
}
/// Sets the size of the plane mesh.
#[inline]
pub fn size(mut self, width: f32, height: f32) -> Self {
self.plane.half_size = Vec2::new(width, height) / 2.0;
self
}
/// Sets the subdivisions of the plane mesh.
///
/// 0 - is the original plane geometry, the 4 points in the XZ plane.
///
/// 1 - is split by 1 line in the middle of the plane on both the X axis and the Z axis,
/// resulting in a plane with 4 quads / 8 triangles.
///
/// 2 - is a plane split by 2 lines on both the X and Z axes, subdividing the plane into 3
/// equal sections along each axis, resulting in a plane with 9 quads / 18 triangles.
#[inline]
pub fn subdivisions(mut self, subdivisions: u32) -> Self {
self.subdivisions = subdivisions;
self
}
}
impl MeshBuilder for PlaneMeshBuilder {
fn build(&self) -> Mesh {
let z_vertex_count = self.subdivisions + 2;
let x_vertex_count = self.subdivisions + 2;
let num_vertices = (z_vertex_count * x_vertex_count) as usize;
let num_indices = ((z_vertex_count - 1) * (x_vertex_count - 1) * 6) as usize;
let mut positions: Vec<Vec3> = Vec::with_capacity(num_vertices);
let mut normals: Vec<[f32; 3]> = Vec::with_capacity(num_vertices);
let mut uvs: Vec<[f32; 2]> = Vec::with_capacity(num_vertices);
let mut indices: Vec<u32> = Vec::with_capacity(num_indices);
let rotation = Quat::from_rotation_arc(Vec3::Y, *self.plane.normal);
let size = self.plane.half_size * 2.0;
for z in 0..z_vertex_count {
for x in 0..x_vertex_count {
let tx = x as f32 / (x_vertex_count - 1) as f32;
let tz = z as f32 / (z_vertex_count - 1) as f32;
let pos = rotation * Vec3::new((-0.5 + tx) * size.x, 0.0, (-0.5 + tz) * size.y);
positions.push(pos);
normals.push(self.plane.normal.to_array());
uvs.push([tx, tz]);
}
}
for z in 0..z_vertex_count - 1 {
for x in 0..x_vertex_count - 1 {
let quad = z * x_vertex_count + x;
indices.push(quad + x_vertex_count + 1);
indices.push(quad + 1);
indices.push(quad + x_vertex_count);
indices.push(quad);
indices.push(quad + x_vertex_count);
indices.push(quad + 1);
}
}
Mesh::new(
PrimitiveTopology::TriangleList,
RenderAssetUsages::default(),
)
.with_inserted_indices(Indices::U32(indices))
.with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, positions)
.with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, normals)
.with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, uvs)
}
}
impl Meshable for Plane3d {
type Output = PlaneMeshBuilder;
fn mesh(&self) -> Self::Output {
PlaneMeshBuilder {
plane: *self,
subdivisions: 0,
}
}
}
impl From<Plane3d> for Mesh {
fn from(plane: Plane3d) -> Self {
plane.mesh().build()
}
}