Galactica/crates/render/src/globaluniform/globaluniform.rs

use galactica_constants::{IMAGE_LIMIT, SPRITE_LIMIT};
use wgpu;

use super::{AtlasContent, DataContent, SpriteContent};

pub struct GlobalUniform {
	pub data_buffer: wgpu::Buffer,
	pub atlas_buffer: wgpu::Buffer,
	pub sprite_buffer: wgpu::Buffer,
	pub bind_group: wgpu::BindGroup,
	pub bind_group_layout: wgpu::BindGroupLayout,
	pub content: DataContent,
}

impl GlobalUniform {
	pub fn shader_header(&self, group: u32) -> String {
		let mut out = String::new();

		out.push_str(&format!("@group({group}) @binding(0)\n"));
		out.push_str(
			r#"
			var<uniform> global: GlobalUniform;
			struct GlobalUniform {
				camera_position: vec2<f32>,
				camera_zoom: vec2<f32>,
				camera_zoom_limits: vec2<f32>,
				window_size: vec2<f32>,
				window_aspect: vec2<f32>,
				starfield_sprite: vec2<u32>,
				starfield_tile_size: vec2<f32>,
				starfield_size_limits: vec2<f32>,
				current_time: vec2<f32>,
			};
			"#,
		);
		out.push_str("\n");

		out.push_str(&format!("@group({group}) @binding(1)\n"));
		out.push_str(
			r#"
			var<uniform> atlas: AtlasUniform;
			struct ImageLocation {
				xpos: f32,
				ypos: f32,
				width: f32,
				height: f32,
			};
			"#,
		);
		out.push_str(&format!(
			r#"
			struct AtlasUniform {{
				data: array<ImageLocation, {}>,
			}};
			"#,
			IMAGE_LIMIT,
		));
		out.push_str("\n");

		// TODO: document
		// wgpu uniforms require constant item sizes.
		// if you get an error like the following,check!
		// `Buffer is bound with size 3456 where the shader expects 5184 in group[1] compact index 2`
		// More notes are in datacontent

		out.push_str(&format!("@group({group}) @binding(2)\n"));
		out.push_str(
			r#"
			var<uniform> sprites: SpriteUniform;
			struct SpriteData {
				frame_count: u32,
				repeatmode: u32,
				aspect: f32,
				fps: f32,
				first_frame: u32,

				padding_a: f32,
				padding_b: f32,
				padding_c: f32,
			};
			"#,
		);
		out.push_str(&format!(
			r#"
			struct SpriteUniform {{
				data: array<SpriteData, {}>,
			}};
			"#,
			SPRITE_LIMIT,
		));
		out.push_str("\n");

		return out;
	}

	pub fn new(device: &wgpu::Device) -> Self {
		let data_buffer = device.create_buffer(&wgpu::BufferDescriptor {
			label: Some("global uniform data buffer"),
			size: DataContent::SIZE,
			usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
			mapped_at_creation: false,
		});

		let atlas_buffer = device.create_buffer(&wgpu::BufferDescriptor {
			label: Some("global uniform atlas buffer"),
			size: AtlasContent::SIZE,
			usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
			mapped_at_creation: false,
		});

		let sprite_buffer = device.create_buffer(&wgpu::BufferDescriptor {
			label: Some("global uniform sprite buffer"),
			size: SpriteContent::SIZE,
			usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
			mapped_at_creation: false,
		});

		let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
			entries: &[
				wgpu::BindGroupLayoutEntry {
					binding: 0,
					visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
					ty: wgpu::BindingType::Buffer {
						ty: wgpu::BufferBindingType::Uniform,
						has_dynamic_offset: false,
						min_binding_size: None,
					},
					count: None,
				},
				wgpu::BindGroupLayoutEntry {
					binding: 1,
					visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
					ty: wgpu::BindingType::Buffer {
						ty: wgpu::BufferBindingType::Uniform,
						has_dynamic_offset: false,
						min_binding_size: None,
					},
					count: None,
				},
				wgpu::BindGroupLayoutEntry {
					binding: 2,
					visibility: wgpu::ShaderStages::VERTEX_FRAGMENT,
					ty: wgpu::BindingType::Buffer {
						ty: wgpu::BufferBindingType::Uniform,
						has_dynamic_offset: false,
						min_binding_size: None,
					},
					count: None,
				},
			],
			label: Some("global uniform bind group layout"),
		});

		let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
			layout: &bind_group_layout,
			entries: &[
				wgpu::BindGroupEntry {
					binding: 0,
					resource: data_buffer.as_entire_binding(),
				},
				wgpu::BindGroupEntry {
					binding: 1,
					resource: atlas_buffer.as_entire_binding(),
				},
				wgpu::BindGroupEntry {
					binding: 2,
					resource: sprite_buffer.as_entire_binding(),
				},
			],
			label: Some("global uniform bind group"),
		});

		return Self {
			data_buffer,
			atlas_buffer,
			sprite_buffer,
			bind_group,
			bind_group_layout,
			content: DataContent::default(),
		};
	}
}