mesh generation

engine/world_generation/src/mesh_generator.rs

@@ -1,6 +1,73 @@
-mod data;
-use data::Chunk;
+use crate::{
+	hex_utils::{to_hex_pos, INNER_RADIUS, OUTER_RADIUS},
+	prelude::*,
+};
+use bevy::{
+	prelude::*,
+	render::{
+		mesh::{Indices, PrimitiveTopology},
+		render_asset::RenderAssetUsages,
+	},
+};
 
-pub fn generate_chunk_mesh(chunk: &Chunk){
+const HEX_CORNERS: [Vec3; 6] = [
+	Vec3::new(0., 0., OUTER_RADIUS),
+	Vec3::new(INNER_RADIUS, 0., 0.5 * OUTER_RADIUS),
+	Vec3::new(INNER_RADIUS, 0., -0.5 * OUTER_RADIUS),
+	Vec3::new(0., 0., -OUTER_RADIUS),
+	Vec3::new(-INNER_RADIUS, 0., -0.5 * OUTER_RADIUS),
+	Vec3::new(-INNER_RADIUS, 0., 0.5 * OUTER_RADIUS),
+];
 
-}
+pub fn generate_chunk_mesh(chunk: &Chunk) -> Mesh {
+	let vertex_count: usize = chunk.size * chunk.size;
+	let mut verts = Vec::with_capacity(vertex_count);
+	let mut uvs = Vec::with_capacity(vertex_count);
+	let mut normals = Vec::with_capacity(vertex_count);
+	let mut indices = Vec::with_capacity(vertex_count);
+
+	for z in 0..chunk.size {
+		for x in 0..chunk.size {
+			let height = chunk.points[x + z * chunk.size];
+			let off_pos = Vec3::new(x as f32, height, z as f32);
+			let grid_pos = to_hex_pos(off_pos);
+			create_tile(grid_pos, &mut verts, &mut uvs, &mut normals, &mut indices);
+		}
+	}
+
+	let mesh = Mesh::new(
+		PrimitiveTopology::TriangleList,
+		RenderAssetUsages::MAIN_WORLD | RenderAssetUsages::RENDER_WORLD,
+	)
+	.with_inserted_attribute(Mesh::ATTRIBUTE_POSITION, verts)
+	.with_inserted_attribute(Mesh::ATTRIBUTE_UV_0, uvs)
+	// .with_inserted_attribute(Mesh::ATTRIBUTE_NORMAL, normals)
+	.with_inserted_indices(Indices::U32(indices))
+	.with_duplicated_vertices()
+	.with_computed_flat_normals();
+	return mesh;
+}
+
+//TODO: figure out texture index
+fn create_tile(
+	pos: Vec3,
+	verts: &mut Vec<Vec3>,
+	uvs: &mut Vec<Vec2>,
+	normals: &mut Vec<Vec3>,
+	indices: &mut Vec<u32>,
+) {
+	let idx = verts.len() as u32;
+	let center = Vec3::new(pos.x, 0., pos.z);
+	normals.push(Vec3::Y);
+	uvs.push(pos.xz());
+	verts.push(pos);
+	for i in 0..6 {
+		let p = pos + HEX_CORNERS[i];
+		verts.push(p);
+		uvs.push(p.xz());
+		normals.push((p - center).normalize());
+		indices.push(idx);
+		indices.push(idx + 1 + i as u32);
+		indices.push(idx + 1 + ((i as u32 + 1) % 6));
+	}
+}