refactor project structure (start of redoing atomic branch without atomics)

core/src/render/data.rs

@@ -0,0 +1,50 @@
+use crate::{layout::UiRegion, util::Id};
+use wgpu::*;
+
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable, Default)]
+pub struct WindowUniform {
+    pub width: f32,
+    pub height: f32,
+}
+
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct PrimitiveInstance {
+    pub region: UiRegion,
+    pub binding: u32,
+    pub idx: u32,
+    pub mask_idx: MaskIdx,
+}
+
+impl PrimitiveInstance {
+    const ATTRIBS: [VertexAttribute; 7] = vertex_attr_array![
+        0 => Float32x2,
+        1 => Float32x2,
+        2 => Float32x2,
+        3 => Float32x2,
+        4 => Uint32,
+        5 => Uint32,
+        6 => Uint32,
+    ];
+
+    pub fn desc() -> VertexBufferLayout<'static> {
+        VertexBufferLayout {
+            array_stride: std::mem::size_of::<Self>() as BufferAddress,
+            step_mode: VertexStepMode::Instance,
+            attributes: &Self::ATTRIBS,
+        }
+    }
+}
+
+pub type MaskIdx = Id<u32>;
+
+impl MaskIdx {
+    pub const NONE: Self = Self::preset(u32::MAX);
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct Mask {
+    pub region: UiRegion,
+}

core/src/render/mod.rs

@@ -0,0 +1,356 @@
+use std::num::NonZero;
+
+use crate::{
+    layout::Ui,
+    render::{data::PrimitiveInstance, texture::GpuTextures, util::ArrBuf},
+    util::HashMap,
+};
+use data::WindowUniform;
+use wgpu::{
+    util::{BufferInitDescriptor, DeviceExt},
+    *,
+};
+use winit::dpi::PhysicalSize;
+
+mod data;
+mod primitive;
+mod texture;
+mod util;
+
+pub use data::{Mask, MaskIdx};
+pub use primitive::*;
+
+const SHAPE_SHADER: &str = include_str!("./shader.wgsl");
+
+pub struct UiRenderNode {
+    uniform_group: BindGroup,
+    primitive_layout: BindGroupLayout,
+    rsc_layout: BindGroupLayout,
+    rsc_group: BindGroup,
+
+    pipeline: RenderPipeline,
+
+    layers: HashMap<usize, RenderLayer>,
+    active: Vec<usize>,
+    window_buffer: Buffer,
+    textures: GpuTextures,
+    masks: ArrBuf<Mask>,
+}
+
+struct RenderLayer {
+    instance: ArrBuf<PrimitiveInstance>,
+    primitives: PrimitiveBuffers,
+    primitive_group: BindGroup,
+}
+
+impl UiRenderNode {
+    pub fn draw<'a>(&'a self, pass: &mut RenderPass<'a>) {
+        pass.set_pipeline(&self.pipeline);
+        pass.set_bind_group(0, &self.uniform_group, &[]);
+        pass.set_bind_group(2, &self.rsc_group, &[]);
+        for i in &self.active {
+            let layer = &self.layers[i];
+            if layer.instance.len() == 0 {
+                continue;
+            }
+            pass.set_bind_group(1, &layer.primitive_group, &[]);
+            pass.set_vertex_buffer(0, layer.instance.buffer.slice(..));
+            pass.draw(0..4, 0..layer.instance.len() as u32);
+        }
+    }
+
+    pub fn update(&mut self, device: &Device, queue: &Queue, ui: &mut Ui) {
+        self.active.clear();
+        for (i, primitives) in ui.data.layers.iter_mut() {
+            self.active.push(i);
+            for change in primitives.apply_free() {
+                if let Some(inst) = ui.data.active.get_mut(&change.id) {
+                    for h in &mut inst.primitives {
+                        if h.layer == i && h.inst_idx == change.old {
+                            h.inst_idx = change.new;
+                            break;
+                        }
+                    }
+                }
+            }
+            let rlayer = self.layers.entry(i).or_insert_with(|| {
+                let primitives = PrimitiveBuffers::new(device);
+                let primitive_group =
+                    Self::primitive_group(device, &self.primitive_layout, primitives.buffers());
+                RenderLayer {
+                    instance: ArrBuf::new(
+                        device,
+                        BufferUsages::VERTEX | BufferUsages::COPY_DST,
+                        "instance",
+                    ),
+                    primitives,
+                    primitive_group,
+                }
+            });
+            if primitives.updated {
+                rlayer
+                    .instance
+                    .update(device, queue, primitives.instances());
+                rlayer.primitives.update(device, queue, primitives.data());
+                rlayer.primitive_group = Self::primitive_group(
+                    device,
+                    &self.primitive_layout,
+                    rlayer.primitives.buffers(),
+                );
+                primitives.updated = false;
+            }
+        }
+        let mut changed = false;
+        changed |= self.textures.update(&mut ui.data.textures);
+        if ui.data.masks.changed {
+            ui.data.masks.changed = false;
+            self.masks.update(device, queue, &ui.data.masks[..]);
+            changed = true;
+        }
+        if changed {
+            self.rsc_group = Self::rsc_group(device, &self.rsc_layout, &self.textures, &self.masks);
+        }
+    }
+
+    pub fn resize(&mut self, size: &PhysicalSize<u32>, queue: &Queue) {
+        let slice = &[WindowUniform {
+            width: size.width as f32,
+            height: size.height as f32,
+        }];
+        queue.write_buffer(&self.window_buffer, 0, bytemuck::cast_slice(slice));
+    }
+
+    pub fn new(
+        device: &Device,
+        queue: &Queue,
+        config: &SurfaceConfiguration,
+        limits: UiLimits,
+    ) -> Self {
+        let shader = device.create_shader_module(ShaderModuleDescriptor {
+            label: Some("UI Shape Shader"),
+            source: ShaderSource::Wgsl(SHAPE_SHADER.into()),
+        });
+
+        let window_uniform = WindowUniform::default();
+        let window_buffer = device.create_buffer_init(&BufferInitDescriptor {
+            label: Some("window"),
+            contents: bytemuck::cast_slice(&[window_uniform]),
+            usage: BufferUsages::UNIFORM | BufferUsages::COPY_DST,
+        });
+
+        let uniform_layout = device.create_bind_group_layout(&BindGroupLayoutDescriptor {
+            entries: &[BindGroupLayoutEntry {
+                binding: 0,
+                visibility: ShaderStages::VERTEX | ShaderStages::FRAGMENT,
+                ty: BindingType::Buffer {
+                    ty: BufferBindingType::Uniform,
+                    has_dynamic_offset: false,
+                    min_binding_size: None,
+                },
+                count: None,
+            }],
+            label: Some("window"),
+        });
+
+        let uniform_group = Self::bind_group_0(device, &uniform_layout, &window_buffer);
+
+        let primitive_layout = device.create_bind_group_layout(&BindGroupLayoutDescriptor {
+            entries: &core::array::from_fn::<_, { PrimitiveBuffers::LEN }, _>(|i| {
+                BindGroupLayoutEntry {
+                    binding: i as u32,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Buffer {
+                        ty: BufferBindingType::Storage { read_only: true },
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                }
+            }),
+            label: Some("primitive"),
+        });
+
+        let tex_manager = GpuTextures::new(device, queue);
+        let masks = ArrBuf::new(
+            device,
+            BufferUsages::STORAGE | BufferUsages::COPY_DST,
+            "ui masks",
+        );
+
+        let rsc_layout = Self::rsc_layout(device, &limits);
+        let rsc_group = Self::rsc_group(device, &rsc_layout, &tex_manager, &masks);
+
+        let pipeline_layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
+            label: Some("UI Shape Pipeline Layout"),
+            bind_group_layouts: &[&uniform_layout, &primitive_layout, &rsc_layout],
+            push_constant_ranges: &[],
+        });
+        let pipeline = device.create_render_pipeline(&RenderPipelineDescriptor {
+            label: Some("UI Shape Pipeline"),
+            layout: Some(&pipeline_layout),
+            vertex: VertexState {
+                module: &shader,
+                entry_point: Some("vs_main"),
+                buffers: &[PrimitiveInstance::desc()],
+                compilation_options: Default::default(),
+            },
+            fragment: Some(FragmentState {
+                module: &shader,
+                entry_point: Some("fs_main"),
+                targets: &[Some(ColorTargetState {
+                    format: config.format,
+                    blend: Some(BlendState::ALPHA_BLENDING),
+                    write_mask: ColorWrites::ALL,
+                })],
+                compilation_options: Default::default(),
+            }),
+            primitive: PrimitiveState {
+                topology: PrimitiveTopology::TriangleStrip,
+                strip_index_format: None,
+                front_face: FrontFace::Cw,
+                cull_mode: Some(Face::Back),
+                polygon_mode: PolygonMode::Fill,
+                unclipped_depth: false,
+                conservative: false,
+            },
+            depth_stencil: None,
+            multisample: MultisampleState {
+                count: 1,
+                mask: !0,
+                alpha_to_coverage_enabled: false,
+            },
+            multiview: None,
+            cache: None,
+        });
+
+        Self {
+            uniform_group,
+            primitive_layout,
+            rsc_layout,
+            rsc_group,
+            pipeline,
+            window_buffer,
+            layers: HashMap::default(),
+            active: Vec::new(),
+            textures: tex_manager,
+            masks,
+        }
+    }
+
+    fn bind_group_0(
+        device: &Device,
+        layout: &BindGroupLayout,
+        window_buffer: &Buffer,
+    ) -> BindGroup {
+        device.create_bind_group(&BindGroupDescriptor {
+            layout,
+            entries: &[BindGroupEntry {
+                binding: 0,
+                resource: window_buffer.as_entire_binding(),
+            }],
+            label: Some("ui window"),
+        })
+    }
+
+    fn primitive_group(
+        device: &Device,
+        layout: &BindGroupLayout,
+        buffers: [(u32, &Buffer); PrimitiveBuffers::LEN],
+    ) -> BindGroup {
+        device.create_bind_group(&BindGroupDescriptor {
+            layout,
+            entries: &buffers.map(|(binding, buf)| BindGroupEntry {
+                binding,
+                resource: buf.as_entire_binding(),
+            }),
+            label: Some("ui primitives"),
+        })
+    }
+
+    fn rsc_layout(device: &Device, limits: &UiLimits) -> BindGroupLayout {
+        device.create_bind_group_layout(&BindGroupLayoutDescriptor {
+            entries: &[
+                BindGroupLayoutEntry {
+                    binding: 0,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Texture {
+                        sample_type: TextureSampleType::Float { filterable: false },
+                        view_dimension: TextureViewDimension::D2,
+                        multisampled: false,
+                    },
+                    count: Some(NonZero::new(limits.max_textures).unwrap()),
+                },
+                BindGroupLayoutEntry {
+                    binding: 1,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Sampler(SamplerBindingType::NonFiltering),
+                    count: Some(NonZero::new(limits.max_samplers).unwrap()),
+                },
+                BindGroupLayoutEntry {
+                    binding: 2,
+                    visibility: ShaderStages::FRAGMENT,
+                    ty: BindingType::Buffer {
+                        ty: BufferBindingType::Storage { read_only: true },
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                },
+            ],
+            label: Some("ui rsc"),
+        })
+    }
+
+    fn rsc_group(
+        device: &Device,
+        layout: &BindGroupLayout,
+        tex_manager: &GpuTextures,
+        masks: &ArrBuf<Mask>,
+    ) -> BindGroup {
+        device.create_bind_group(&BindGroupDescriptor {
+            layout,
+            entries: &[
+                BindGroupEntry {
+                    binding: 0,
+                    resource: BindingResource::TextureViewArray(&tex_manager.views()),
+                },
+                BindGroupEntry {
+                    binding: 1,
+                    resource: BindingResource::SamplerArray(&tex_manager.samplers()),
+                },
+                BindGroupEntry {
+                    binding: 2,
+                    resource: masks.buffer.as_entire_binding(),
+                },
+            ],
+            label: Some("ui rsc"),
+        })
+    }
+
+    pub fn view_count(&self) -> usize {
+        self.textures.view_count()
+    }
+}
+
+pub struct UiLimits {
+    max_textures: u32,
+    max_samplers: u32,
+}
+
+impl Default for UiLimits {
+    fn default() -> Self {
+        Self {
+            max_textures: 100000,
+            max_samplers: 1000,
+        }
+    }
+}
+
+impl UiLimits {
+    pub fn max_binding_array_elements_per_shader_stage(&self) -> u32 {
+        self.max_textures + self.max_samplers
+    }
+    pub fn max_binding_array_sampler_elements_per_shader_stage(&self) -> u32 {
+        self.max_samplers
+    }
+}

core/src/render/primitive.rs

@@ -0,0 +1,283 @@
+use std::ops::{Deref, DerefMut};
+
+use crate::{
+    layout::{Color, UiRegion},
+    render::{
+        ArrBuf,
+        data::{MaskIdx, PrimitiveInstance},
+    },
+    util::Id,
+};
+use bytemuck::Pod;
+use wgpu::*;
+
+pub struct Primitives {
+    instances: Vec<PrimitiveInstance>,
+    assoc: Vec<Id>,
+    data: PrimitiveData,
+    free: Vec<usize>,
+    pub updated: bool,
+}
+
+impl Default for Primitives {
+    fn default() -> Self {
+        Self {
+            instances: Default::default(),
+            assoc: Default::default(),
+            data: Default::default(),
+            free: Vec::new(),
+            updated: true,
+        }
+    }
+}
+
+pub trait Primitive: Pod {
+    const BINDING: u32;
+    fn vec(data: &mut PrimitiveData) -> &mut PrimitiveVec<Self>;
+}
+
+macro_rules! primitives {
+    ($($name:ident: $ty:ty => $binding:expr,)*) => {
+        #[derive(Default)]
+        pub struct PrimitiveData {
+            $(pub(crate) $name: PrimitiveVec<$ty>,)*
+        }
+
+        pub struct PrimitiveBuffers {
+            $($name: ArrBuf<$ty>,)*
+        }
+
+        impl PrimitiveBuffers {
+            pub fn update(&mut self, device: &Device, queue: &Queue, data: &PrimitiveData) {
+                $(self.$name.update(device, queue, &data.$name);)*
+            }
+        }
+
+        impl PrimitiveBuffers {
+            pub const LEN: usize = primitives!(@count $($name)*);
+            pub fn buffers(&self) -> [(u32, &Buffer); Self::LEN] {
+                [
+                    $((<$ty>::BINDING, &self.$name.buffer),)*
+                ]
+            }
+            pub fn new(device: &Device) -> Self {
+                Self {
+                    $($name: ArrBuf::new(
+                        device,
+                        BufferUsages::STORAGE | BufferUsages::COPY_DST,
+                        stringify!($name),
+                    ),)*
+                }
+            }
+        }
+
+        impl PrimitiveData {
+            pub fn clear(&mut self) {
+                $(self.$name.clear();)*
+            }
+            pub fn free(&mut self, binding: u32, idx: usize) {
+                match binding {
+                    $(<$ty>::BINDING => self.$name.free(idx),)*
+                    _ => unreachable!()
+                }
+            }
+        }
+
+        $(
+            unsafe impl bytemuck::Pod for $ty {}
+            unsafe impl bytemuck::Zeroable for $ty {}
+            impl Primitive for $ty {
+                const BINDING: u32 = $binding;
+                fn vec(data: &mut PrimitiveData) -> &mut PrimitiveVec<Self> {
+                    &mut data.$name
+                }
+            }
+        )*
+    };
+    (@count $t1:tt $($t:tt)+) => { 1 + primitives!(@count $($t),+) };
+    (@count $t:tt) => { 1 };
+}
+
+pub struct PrimitiveInst<P> {
+    pub id: Id,
+    pub primitive: P,
+    pub region: UiRegion,
+    pub mask_idx: MaskIdx,
+}
+
+impl Primitives {
+    pub fn write<P: Primitive>(
+        &mut self,
+        layer: usize,
+        PrimitiveInst {
+            id,
+            primitive,
+            region,
+            mask_idx,
+        }: PrimitiveInst<P>,
+    ) -> PrimitiveHandle {
+        self.updated = true;
+        let vec = P::vec(&mut self.data);
+        let i = vec.add(primitive);
+        let inst = PrimitiveInstance {
+            region,
+            idx: i as u32,
+            mask_idx,
+            binding: P::BINDING,
+        };
+        let inst_i = if let Some(i) = self.free.pop() {
+            self.instances[i] = inst;
+            self.assoc[i] = id;
+            i
+        } else {
+            let i = self.instances.len();
+            self.instances.push(inst);
+            self.assoc.push(id);
+            i
+        };
+        PrimitiveHandle::new::<P>(layer, inst_i, i)
+    }
+
+    /// returns (old index, new index)
+    pub fn apply_free(&mut self) -> impl Iterator<Item = PrimitiveChange> {
+        self.free.sort_by(|a, b| b.cmp(a));
+        self.free.drain(..).filter_map(|i| {
+            self.instances.swap_remove(i);
+            self.assoc.swap_remove(i);
+            if i == self.instances.len() {
+                return None;
+            }
+            let id = self.assoc[i];
+            let old = self.instances.len();
+            Some(PrimitiveChange { id, old, new: i })
+        })
+    }
+
+    pub fn free(&mut self, h: &PrimitiveHandle) -> MaskIdx {
+        self.updated = true;
+        self.data.free(h.binding, h.data_idx);
+        self.free.push(h.inst_idx);
+        self.instances[h.inst_idx].mask_idx
+    }
+
+    pub fn data(&self) -> &PrimitiveData {
+        &self.data
+    }
+
+    pub fn instances(&self) -> &Vec<PrimitiveInstance> {
+        &self.instances
+    }
+
+    pub fn region_mut(&mut self, h: &PrimitiveHandle) -> &mut UiRegion {
+        self.updated = true;
+        &mut self.instances[h.inst_idx].region
+    }
+}
+
+pub struct PrimitiveChange {
+    pub id: Id,
+    pub old: usize,
+    pub new: usize,
+}
+
+#[derive(Debug)]
+pub struct PrimitiveHandle {
+    pub layer: usize,
+    pub inst_idx: usize,
+    pub data_idx: usize,
+    pub binding: u32,
+}
+
+impl PrimitiveHandle {
+    fn new<P: Primitive>(layer: usize, inst_idx: usize, data_idx: usize) -> Self {
+        Self {
+            layer,
+            inst_idx,
+            data_idx,
+            binding: P::BINDING,
+        }
+    }
+}
+
+primitives!(
+    rects: RectPrimitive => 0,
+    textures: TexturePrimitive => 1,
+);
+
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub struct RectPrimitive {
+    pub color: Color<u8>,
+    pub radius: f32,
+    pub thickness: f32,
+    pub inner_radius: f32,
+}
+
+impl RectPrimitive {
+    pub fn color(color: Color<u8>) -> Self {
+        Self {
+            color,
+            radius: 0.0,
+            thickness: 0.0,
+            inner_radius: 0.0,
+        }
+    }
+}
+
+#[repr(C)]
+#[derive(Debug, Copy, Clone)]
+pub struct TexturePrimitive {
+    pub view_idx: u32,
+    pub sampler_idx: u32,
+}
+
+pub struct PrimitiveVec<T> {
+    vec: Vec<T>,
+    free: Vec<usize>,
+}
+
+impl<T> PrimitiveVec<T> {
+    pub fn new() -> Self {
+        Self {
+            vec: Vec::new(),
+            free: Vec::new(),
+        }
+    }
+    pub fn add(&mut self, t: T) -> usize {
+        if let Some(i) = self.free.pop() {
+            self.vec[i] = t;
+            i
+        } else {
+            let i = self.vec.len();
+            self.vec.push(t);
+            i
+        }
+    }
+    pub fn free(&mut self, i: usize) {
+        self.free.push(i);
+    }
+    pub fn clear(&mut self) {
+        self.free.clear();
+        self.vec.clear();
+    }
+}
+
+impl<T> Default for PrimitiveVec<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T> Deref for PrimitiveVec<T> {
+    type Target = Vec<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.vec
+    }
+}
+
+impl<T> DerefMut for PrimitiveVec<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.vec
+    }
+}

core/src/render/shader.wgsl

@@ -0,0 +1,178 @@
+const RECT: u32 = 0u;
+const TEXTURE: u32 = 1u;
+
+@group(0) @binding(0)
+var<uniform> window: WindowUniform;
+@group(1) @binding(RECT)
+var<storage> rects: array<Rect>;
+@group(1) @binding(TEXTURE)
+var<storage> textures: array<TextureInfo>;
+
+struct Rect {
+    color: u32,
+    radius: f32,
+    thickness: f32,
+    inner_radius: f32,
+}
+
+struct TextureInfo {
+    view_idx: u32,
+    sampler_idx: u32,
+}
+
+struct Mask {
+    x: UiSpan,
+    y: UiSpan,
+}
+
+struct UiSpan {
+    start: UiScalar,
+    end: UiScalar,
+}
+
+struct UiScalar {
+    rel: f32,
+    abs: f32,
+}
+
+struct UiVec2 {
+    rel: vec2<f32>,
+    abs: vec2<f32>,
+}
+
+@group(2) @binding(0)
+var views: binding_array<texture_2d<f32>>;
+@group(2) @binding(1)
+var samplers: binding_array<sampler>;
+@group(2) @binding(2)
+var<storage> masks: array<Mask>;
+
+struct WindowUniform {
+    dim: vec2<f32>,
+};
+
+struct InstanceInput {
+    @location(0) x_start: vec2<f32>,
+    @location(1) x_end: vec2<f32>,
+    @location(2) y_start: vec2<f32>,
+    @location(3) y_end: vec2<f32>,
+    @location(4) binding: u32,
+    @location(5) idx: u32,
+    @location(6) mask_idx: u32,
+}
+
+struct VertexOutput {
+    @location(0) top_left: vec2<f32>,
+    @location(1) bot_right: vec2<f32>,
+    @location(2) uv: vec2<f32>,
+    @location(3) binding: u32,
+    @location(4) idx: u32,
+    @location(5) mask_idx: u32,
+    @builtin(position) clip_position: vec4<f32>,
+};
+
+struct Region {
+    pos: vec2<f32>,
+    uv: vec2<f32>,
+    top_left: vec2<f32>,
+    bot_right: vec2<f32>,
+}
+
+@vertex
+fn vs_main(
+    @builtin(vertex_index) vi: u32,
+    in: InstanceInput,
+) -> VertexOutput {
+    var out: VertexOutput;
+
+    let top_left_rel = vec2(in.x_start.x, in.y_start.x);
+    let top_left_abs = vec2(in.x_start.y, in.y_start.y);
+    let bot_right_rel = vec2(in.x_end.x, in.y_end.x);
+    let bot_right_abs = vec2(in.x_end.y, in.y_end.y);
+
+    let top_left = floor(top_left_rel * window.dim) + floor(top_left_abs);
+    let bot_right = floor(bot_right_rel * window.dim) + floor(bot_right_abs);
+    let size = bot_right - top_left;
+
+    let uv = vec2<f32>(
+        f32(vi % 2u),
+        f32(vi / 2u)
+    );
+    let pos = (top_left + uv * size) / window.dim * 2.0 - 1.0;
+    out.clip_position = vec4<f32>(pos.x, -pos.y, 0.0, 1.0);
+    out.uv = uv;
+    out.binding = in.binding;
+    out.idx = in.idx;
+    out.top_left = top_left;
+    out.bot_right = bot_right;
+    out.mask_idx = in.mask_idx;
+
+    return out;
+}
+
+@fragment
+fn fs_main(
+    in: VertexOutput
+) -> @location(0) vec4<f32> {
+    let pos = in.clip_position.xy;
+    let region = Region(pos, in.uv, in.top_left, in.bot_right);
+    let i = in.idx;
+    var color: vec4<f32>;
+    switch in.binding {
+        case RECT: {
+            color = draw_rounded_rect(region, rects[i]);
+        }
+        case TEXTURE: {
+            color = draw_texture(region, textures[i]);
+        }
+        default: {
+            color = vec4(1.0, 0.0, 1.0, 1.0);
+        }
+    }
+    if in.mask_idx != 4294967295u {
+        let mask = masks[in.mask_idx];
+        let tl = UiVec2(vec2(mask.x.start.rel, mask.y.start.rel), vec2(mask.x.start.abs, mask.y.start.abs));
+        let br = UiVec2(vec2(mask.x.end.rel, mask.y.end.rel), vec2(mask.x.end.abs, mask.y.end.abs));
+
+        let top_left = floor(tl.rel * window.dim) + floor(tl.abs);
+        let bot_right = floor(br.rel * window.dim) + floor(br.abs);
+        if pos.x < top_left.x || pos.x > bot_right.x || pos.y < top_left.y || pos.y > bot_right.y {
+            color *= 0.0;
+        }
+    }
+    return color;
+}
+
+// TODO: this seems really inefficient (per frag indexing)?
+fn draw_texture(region: Region, info: TextureInfo) -> vec4<f32> {
+    return textureSample(views[info.view_idx], samplers[info.sampler_idx], region.uv);
+}
+
+fn draw_rounded_rect(region: Region, rect: Rect) -> vec4<f32> {
+    var color = unpack4x8unorm(rect.color);
+
+    let edge = 0.5;
+
+    let size = region.bot_right - region.top_left;
+    let corner = size / 2.0;
+    let center = region.top_left + corner;
+
+    let dist = distance_from_rect(region.pos, center, corner, rect.radius);
+    color.a *= 1.0 - smoothstep(-min(edge, rect.radius), edge, dist);
+
+    if rect.thickness > 0.0 {
+        let dist2 = distance_from_rect(region.pos, center, corner - rect.thickness, rect.inner_radius);
+        color.a *= smoothstep(-min(edge, rect.inner_radius), edge, dist2);
+    }
+
+    return color;
+}
+
+fn distance_from_rect(pixel_pos: vec2<f32>, rect_center: vec2<f32>, rect_corner: vec2<f32>, radius: f32) -> f32 {
+    // vec from center to pixel
+    let p = pixel_pos - rect_center;
+    // vec from inner rect corner to pixel
+    let q = abs(p) - (rect_corner - radius);
+    return length(max(q, vec2(0.0))) - radius;
+}
+

core/src/render/texture.rs

@@ -0,0 +1,129 @@
+use image::{DynamicImage, EncodableLayout};
+use wgpu::{util::DeviceExt, *};
+
+use crate::layout::{TextureUpdate, Textures};
+
+pub struct GpuTextures {
+    device: Device,
+    queue: Queue,
+    views: Vec<TextureView>,
+    view_count: usize,
+    samplers: Vec<Sampler>,
+    null_view: TextureView,
+    no_views: Vec<TextureView>,
+}
+
+impl GpuTextures {
+    pub fn update(&mut self, textures: &mut Textures) -> bool {
+        let mut changed = false;
+        for update in textures.updates() {
+            changed = true;
+            match update {
+                TextureUpdate::Push(image) => self.push(image),
+                TextureUpdate::Set(i, image) => self.set(i, image),
+                TextureUpdate::SetFree => self.view_count += 1,
+                TextureUpdate::Free(i) => self.free(i),
+                TextureUpdate::PushFree => self.push_free(),
+            }
+        }
+        changed
+    }
+    fn set(&mut self, i: u32, image: &DynamicImage) {
+        self.view_count += 1;
+        let view = self.create_view(image);
+        self.views[i as usize] = view;
+    }
+    fn free(&mut self, i: u32) {
+        self.view_count -= 1;
+        self.views[i as usize] = self.null_view.clone();
+    }
+    fn push(&mut self, image: &DynamicImage) {
+        self.view_count += 1;
+        let view = self.create_view(image);
+        self.views.push(view);
+    }
+    fn push_free(&mut self) {
+        self.view_count += 1;
+        self.views.push(self.null_view.clone());
+    }
+
+    fn create_view(&self, image: &DynamicImage) -> TextureView {
+        let image = image.to_rgba8();
+        let (width, height) = image.dimensions();
+        let texture = self.device.create_texture_with_data(
+            &self.queue,
+            &TextureDescriptor {
+                label: None,
+                size: Extent3d {
+                    width,
+                    height,
+                    depth_or_array_layers: 1,
+                },
+                mip_level_count: 1,
+                sample_count: 1,
+                dimension: TextureDimension::D2,
+                format: TextureFormat::Rgba8Unorm,
+                usage: TextureUsages::TEXTURE_BINDING,
+                view_formats: &[],
+            },
+            wgt::TextureDataOrder::MipMajor,
+            image.as_bytes(),
+        );
+        texture.create_view(&TextureViewDescriptor::default())
+    }
+
+    pub fn new(device: &Device, queue: &Queue) -> Self {
+        let null_view = null_texture_view(device);
+        Self {
+            device: device.clone(),
+            queue: queue.clone(),
+            views: Vec::new(),
+            samplers: vec![default_sampler(device)],
+            no_views: vec![null_view.clone()],
+            null_view,
+            view_count: 0,
+        }
+    }
+
+    pub fn views(&self) -> Vec<&TextureView> {
+        if self.views.is_empty() {
+            &self.no_views
+        } else {
+            &self.views
+        }
+        .iter()
+        .by_ref()
+        .collect()
+    }
+
+    pub fn samplers(&self) -> Vec<&Sampler> {
+        self.samplers.iter().by_ref().collect()
+    }
+
+    pub fn view_count(&self) -> usize {
+        self.view_count
+    }
+}
+
+pub fn null_texture_view(device: &Device) -> TextureView {
+    device
+        .create_texture(&TextureDescriptor {
+            label: Some("null"),
+            size: Extent3d {
+                width: 1,
+                height: 1,
+                depth_or_array_layers: 1,
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: TextureDimension::D2,
+            format: TextureFormat::Rgba8Unorm,
+            usage: TextureUsages::TEXTURE_BINDING,
+            view_formats: &[],
+        })
+        .create_view(&TextureViewDescriptor::default())
+}
+
+pub fn default_sampler(device: &Device) -> Sampler {
+    device.create_sampler(&SamplerDescriptor::default())
+}

core/src/render/util/mod.rs

@@ -0,0 +1,48 @@
+use std::marker::PhantomData;
+
+use bytemuck::Pod;
+use wgpu::*;
+
+pub struct ArrBuf<T: Pod> {
+    label: &'static str,
+    usage: BufferUsages,
+    pub buffer: Buffer,
+    len: usize,
+    _pd: PhantomData<T>,
+}
+
+impl<T: Pod> ArrBuf<T> {
+    pub fn new(device: &Device, usage: BufferUsages, label: &'static str) -> Self {
+        Self {
+            label,
+            usage,
+            buffer: Self::init_buf(device, 0, usage, label),
+            len: 0,
+            _pd: PhantomData,
+        }
+    }
+    pub fn update(&mut self, device: &Device, queue: &Queue, data: &[T]) {
+        if self.len != data.len() {
+            self.len = data.len();
+            self.buffer =
+                Self::init_buf(device, std::mem::size_of_val(data), self.usage, self.label);
+        }
+        queue.write_buffer(&self.buffer, 0, bytemuck::cast_slice(data));
+    }
+    fn init_buf(device: &Device, size: usize, usage: BufferUsages, label: &'static str) -> Buffer {
+        let mut size = size as u64;
+        if usage.contains(BufferUsages::STORAGE) {
+            size = size.max(std::mem::size_of::<T>() as u64);
+        }
+        device.create_buffer(&BufferDescriptor {
+            label: Some(label),
+            size,
+            mapped_at_creation: false,
+            usage,
+        })
+    }
+    #[allow(clippy::len_without_is_empty)]
+    pub fn len(&self) -> usize {
+        self.len
+    }
+}