feat: migrate GPU renderer from WebGL to wgpu/WASM

2 files changed, 261 insertions, 0 deletions

diff --git a/rust/wasm/src/gpu_bridge.rs b/rust/wasm/src/gpu_bridge.rs
new file mode 100644
index 00000000..85db0c8b
--- /dev/null
+++ b/rust/wasm/src/gpu_bridge.rs
@@ -0,0 +1,256 @@
+#![cfg(target_arch = "wasm32")]
+
+use std::cell::RefCell;
+
+use gpu::{EffectPass, GpuContext, UniformValue, wgpu};
+use js_sys::{Object, Reflect};
+use serde::Deserialize;
+use wasm_bindgen::{JsCast, JsValue, prelude::wasm_bindgen};
+
+thread_local! {
+    static GPU_CONTEXT: RefCell<Option<GpuContext>> = const { RefCell::new(None) };
+}
+
+struct ApplyEffectPassesOptions {
+    source: wgpu::web_sys::OffscreenCanvas,
+    width: u32,
+    height: u32,
+    passes: Vec<EffectPassInput>,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct EffectPassInput {
+    shader: String,
+    uniforms: Vec<EffectUniformInput>,
+}
+
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct EffectUniformInput {
+    name: String,
+    value: Vec<f32>,
+}
+
+struct ApplyMaskFeatherOptions {
+    mask: wgpu::web_sys::OffscreenCanvas,
+    width: u32,
+    height: u32,
+    feather: f32,
+}
+
+#[wasm_bindgen(js_name = initializeGpu)]
+pub async fn initialize_gpu() -> Result<(), JsValue> {
+    if GPU_CONTEXT.with(|context| context.borrow().is_some()) {
+        return Ok(());
+    }
+
+    let context = GpuContext::new()
+        .await
+        .map_err(|error| JsValue::from_str(&error.to_string()))?;
+    GPU_CONTEXT.with(|gpu_context| {
+        gpu_context.replace(Some(context));
+    });
+    Ok(())
+}
+
+#[wasm_bindgen(js_name = applyEffectPasses)]
+pub fn apply_effect_passes(
+    options: JsValue,
+) -> Result<wgpu::web_sys::OffscreenCanvas, JsValue> {
+    let ApplyEffectPassesOptions {
+        source,
+        width,
+        height,
+        passes,
+    } = parse_apply_effect_passes_options(options)?;
+
+    with_gpu_context(|context| {
+        let source_texture = import_canvas_texture(context, &source, width, height)?;
+        let effect_passes = map_effect_passes(passes);
+        let result_texture = context
+            .apply_effects(gpu::ApplyEffectsOptions {
+                source: &source_texture,
+                width,
+                height,
+                passes: &effect_passes,
+            })
+            .map_err(|error| JsValue::from_str(&error.to_string()))?;
+        let output_canvas = wgpu::web_sys::OffscreenCanvas::new(width, height)?;
+        let surface = context
+            .instance()
+            .create_surface(wgpu::SurfaceTarget::OffscreenCanvas(output_canvas.clone()))
+            .map_err(|error| JsValue::from_str(&error.to_string()))?;
+
+        context
+            .render_texture_to_surface(&result_texture, &surface, width, height)
+            .map_err(|error| JsValue::from_str(&error.to_string()))?;
+        Ok(output_canvas)
+    })
+}
+
+#[wasm_bindgen(js_name = applyMaskFeather)]
+pub fn apply_mask_feather(
+    options: JsValue,
+) -> Result<wgpu::web_sys::OffscreenCanvas, JsValue> {
+    let ApplyMaskFeatherOptions {
+        mask,
+        width,
+        height,
+        feather,
+    } = parse_apply_mask_feather_options(options)?;
+
+    with_gpu_context(|context| {
+        let mask_texture = import_canvas_texture(context, &mask, width, height)?;
+        let result_texture = context.apply_mask_feather(gpu::ApplyMaskFeatherOptions {
+            mask: &mask_texture,
+            width,
+            height,
+            feather,
+        });
+        let output_canvas = wgpu::web_sys::OffscreenCanvas::new(width, height)?;
+        let surface = context
+            .instance()
+            .create_surface(wgpu::SurfaceTarget::OffscreenCanvas(output_canvas.clone()))
+            .map_err(|error| JsValue::from_str(&error.to_string()))?;
+
+        context
+            .render_texture_to_surface(&result_texture, &surface, width, height)
+            .map_err(|error| JsValue::from_str(&error.to_string()))?;
+        Ok(output_canvas)
+    })
+}
+
+fn with_gpu_context<T>(
+    action: impl FnOnce(&GpuContext) -> Result<T, JsValue>,
+) -> Result<T, JsValue> {
+    GPU_CONTEXT.with(|context| {
+        let borrow = context.borrow();
+        let Some(gpu_context) = borrow.as_ref() else {
+            return Err(JsValue::from_str(
+                "GPU context not initialized. Call initializeGpu() first.",
+            ));
+        };
+        action(gpu_context)
+    })
+}
+
+fn import_canvas_texture(
+    context: &GpuContext,
+    canvas: &wgpu::web_sys::OffscreenCanvas,
+    width: u32,
+    height: u32,
+) -> Result<wgpu::Texture, JsValue> {
+    let texture = context.create_render_texture(width, height, "gpu-bridge-input-texture");
+    context.queue().copy_external_image_to_texture(
+        &wgpu::CopyExternalImageSourceInfo {
+            source: wgpu::ExternalImageSource::OffscreenCanvas(canvas.clone()),
+            origin: wgpu::Origin2d::ZERO,
+            flip_y: true,
+        },
+        wgpu::CopyExternalImageDestInfo {
+            texture: &texture,
+            mip_level: 0,
+            origin: wgpu::Origin3d::ZERO,
+            aspect: wgpu::TextureAspect::All,
+            color_space: wgpu::PredefinedColorSpace::Srgb,
+            premultiplied_alpha: false,
+        },
+        wgpu::Extent3d {
+            width,
+            height,
+            depth_or_array_layers: 1,
+        },
+    );
+    Ok(texture)
+}
+
+fn map_effect_passes(effect_passes: Vec<EffectPassInput>) -> Vec<EffectPass> {
+    effect_passes
+        .into_iter()
+        .map(|pass| EffectPass {
+            shader: pass.shader,
+            uniforms: pass
+                .uniforms
+                .into_iter()
+                .map(|uniform| {
+                    let value = if uniform.value.len() == 1 {
+                        UniformValue::Number(uniform.value[0])
+                    } else {
+                        UniformValue::Vector(uniform.value)
+                    };
+                    (uniform.name, value)
+                })
+                .collect(),
+        })
+        .collect()
+}
+
+fn parse_apply_effect_passes_options(value: JsValue) -> Result<ApplyEffectPassesOptions, JsValue> {
+    let object: Object = value
+        .dyn_into()
+        .map_err(|_| JsValue::from_str("applyEffectPasses expects an options object"))?;
+
+    Ok(ApplyEffectPassesOptions {
+        source: read_offscreen_canvas_property(&object, "source")?,
+        width: read_u32_property(&object, "width")?,
+        height: read_u32_property(&object, "height")?,
+        passes: read_serde_property(&object, "passes")?,
+    })
+}
+
+fn parse_apply_mask_feather_options(value: JsValue) -> Result<ApplyMaskFeatherOptions, JsValue> {
+    let object: Object = value
+        .dyn_into()
+        .map_err(|_| JsValue::from_str("applyMaskFeather expects an options object"))?;
+
+    Ok(ApplyMaskFeatherOptions {
+        mask: read_offscreen_canvas_property(&object, "mask")?,
+        width: read_u32_property(&object, "width")?,
+        height: read_u32_property(&object, "height")?,
+        feather: read_f32_property(&object, "feather")?,
+    })
+}
+
+fn read_property(object: &Object, name: &str) -> Result<JsValue, JsValue> {
+    Reflect::get(object, &JsValue::from_str(name))
+        .map_err(|_| JsValue::from_str(&format!("Missing property '{name}'")))
+}
+
+fn read_offscreen_canvas_property(
+    object: &Object,
+    name: &str,
+) -> Result<wgpu::web_sys::OffscreenCanvas, JsValue> {
+    read_property(object, name)?
+        .dyn_into::<wgpu::web_sys::OffscreenCanvas>()
+        .map_err(|_| JsValue::from_str(&format!("Property '{name}' must be an OffscreenCanvas")))
+}
+
+fn read_u32_property(object: &Object, name: &str) -> Result<u32, JsValue> {
+    let value = read_property(object, name)?;
+    let Some(number) = value.as_f64() else {
+        return Err(JsValue::from_str(&format!(
+            "Property '{name}' must be a number"
+        )));
+    };
+    Ok(number as u32)
+}
+
+fn read_f32_property(object: &Object, name: &str) -> Result<f32, JsValue> {
+    let value = read_property(object, name)?;
+    let Some(number) = value.as_f64() else {
+        return Err(JsValue::from_str(&format!(
+            "Property '{name}' must be a number"
+        )));
+    };
+    Ok(number as f32)
+}
+
+fn read_serde_property<T>(object: &Object, name: &str) -> Result<T, JsValue>
+where
+    T: for<'de> Deserialize<'de>,
+{
+    let value = read_property(object, name)?;
+    serde_wasm_bindgen::from_value(value)
+        .map_err(|error| JsValue::from_str(&format!("Invalid property '{name}': {error}")))
+}
diff --git a/rust/wasm/src/wasm.rs b/rust/wasm/src/wasm.rs
index e852df5f..0a78a314 100644
--- a/rust/wasm/src/wasm.rs
+++ b/rust/wasm/src/wasm.rs
@@ -1 +1,6 @@
+#[cfg(target_arch = "wasm32")]
+mod gpu_bridge;
+
+#[cfg(target_arch = "wasm32")]
+pub use gpu_bridge::*;
 pub use time::*;