pebble-engine 2.0.0

A modular, ECS-style graphics/app framework for Rust.
Documentation 
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use std::collections::HashMap;

use crate::{
    ecs::{commands::Commands, resources::Read},
    graphics::render::Backend,
};

/// One of a fixed set of ready-made samplers, built once at startup and
/// looked up via [`GlobalSamplers`] — no per-texture sampler creation.
#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub enum SamplerKind {
    LinearRepeat,
    LinearClamp,
    LinearClampNoMip,
    Nearest,
    NearestClampBorder,
    CompareLess,
}

impl SamplerKind {
    pub(crate) fn descriptor(&self) -> wgpu::SamplerDescriptor<'static> {
        match self {
            SamplerKind::LinearRepeat => wgpu::SamplerDescriptor {
                address_mode_u: wgpu::AddressMode::Repeat,
                address_mode_v: wgpu::AddressMode::Repeat,
                address_mode_w: wgpu::AddressMode::Repeat,
                mag_filter: wgpu::FilterMode::Linear,
                min_filter: wgpu::FilterMode::Linear,
                mipmap_filter: wgpu::MipmapFilterMode::Linear,
                ..Default::default()
            },
            SamplerKind::LinearClamp => wgpu::SamplerDescriptor {
                address_mode_u: wgpu::AddressMode::ClampToEdge,
                address_mode_v: wgpu::AddressMode::ClampToEdge,
                address_mode_w: wgpu::AddressMode::ClampToEdge,
                mag_filter: wgpu::FilterMode::Linear,
                min_filter: wgpu::FilterMode::Linear,
                mipmap_filter: wgpu::MipmapFilterMode::Linear,
                ..Default::default()
            },
            SamplerKind::LinearClampNoMip => wgpu::SamplerDescriptor {
                address_mode_u: wgpu::AddressMode::ClampToEdge,
                address_mode_v: wgpu::AddressMode::ClampToEdge,
                address_mode_w: wgpu::AddressMode::ClampToEdge,
                mag_filter: wgpu::FilterMode::Linear,
                min_filter: wgpu::FilterMode::Linear,
                mipmap_filter: wgpu::MipmapFilterMode::Linear,
                lod_min_clamp: 0.0,
                lod_max_clamp: 0.0,
                ..Default::default()
            },
            SamplerKind::Nearest => wgpu::SamplerDescriptor {
                mag_filter: wgpu::FilterMode::Nearest,
                min_filter: wgpu::FilterMode::Nearest,
                mipmap_filter: wgpu::MipmapFilterMode::Linear,
                ..Default::default()
            },
            SamplerKind::NearestClampBorder => {
                let address_mode = if cfg!(target_arch = "wasm32") {
                    wgpu::AddressMode::ClampToEdge
                } else {
                    wgpu::AddressMode::ClampToBorder
                };
                wgpu::SamplerDescriptor {
                    address_mode_u: address_mode,
                    address_mode_v: address_mode,
                    address_mode_w: address_mode,
                    mag_filter: wgpu::FilterMode::Nearest,
                    min_filter: wgpu::FilterMode::Nearest,
                    mipmap_filter: wgpu::MipmapFilterMode::Nearest,
                    border_color: if cfg!(target_arch = "wasm32") {
                        None
                    } else {
                        Some(wgpu::SamplerBorderColor::OpaqueWhite)
                    },
                    ..Default::default()
                }
            }
            SamplerKind::CompareLess => wgpu::SamplerDescriptor {
                address_mode_u: wgpu::AddressMode::ClampToEdge,
                address_mode_v: wgpu::AddressMode::ClampToEdge,
                address_mode_w: wgpu::AddressMode::ClampToEdge,
                mag_filter: wgpu::FilterMode::Linear,
                min_filter: wgpu::FilterMode::Linear,
                mipmap_filter: wgpu::MipmapFilterMode::Linear,
                compare: Some(wgpu::CompareFunction::Less),
                ..Default::default()
            },
        }
    }
}

const ALL_SAMPLER_KINDS: [SamplerKind; 6] = [
    SamplerKind::LinearRepeat,
    SamplerKind::LinearClamp,
    SamplerKind::LinearClampNoMip,
    SamplerKind::Nearest,
    SamplerKind::NearestClampBorder,
    SamplerKind::CompareLess,
];

/// A GPU sampler, wrapping `wgpu::Sampler`.
pub struct Sampler(wgpu::Sampler);

impl Sampler {
    pub(crate) fn raw(&self) -> &wgpu::Sampler {
        &self.0
    }
}

/// Every [`SamplerKind`], pre-built — inserted as a resource by
/// [`BuiltinAssetsPlugin`](crate::graphics::BuiltinAssetsPlugin).
pub struct GlobalSamplers {
    samplers: HashMap<SamplerKind, Sampler>,
}

impl GlobalSamplers {
    pub fn get(&self, kind: SamplerKind) -> &Sampler {
        self.samplers
            .get(&kind)
            .expect("GlobalSamplers: all SamplerKind variants are built at construction")
    }
}

pub(crate) fn init_global_samplers(
    backend: Option<Read<Backend>>,
    existing: Option<Read<GlobalSamplers>>,
    mut commands: Commands,
) {
    if existing.is_some() {
        return;
    }
    let Some(backend) = backend else {
        return;
    };
    let samplers = ALL_SAMPLER_KINDS
        .iter()
        .map(|&kind| (kind, Sampler(backend.device.create_sampler(&kind.descriptor()))))
        .collect();
    commands.insert_resource(GlobalSamplers { samplers });
}