Pulled the rain render out of the render bundle, I won't likely benefit from it.

Threw together renderToCanvas, which renders a texture to the canvas texture.

shaders/wgsl/renderToCanvas.wgsl

@@ -0,0 +1,17 @@
+[[group(0), binding(0)]] var inputSampler : sampler;
+[[group(0), binding(1)]] var inputTexture : texture_2d<f32>;
+
+struct VertOutput {
+	[[builtin(position)]] Position : vec4<f32>;
+	[[location(0)]] uv : vec2<f32>;
+};
+
+[[stage(vertex)]] fn vertMain([[builtin(vertex_index)]] index : u32) -> VertOutput {
+	var uv = vec2<f32>(f32(index % 2u), f32((index + 1u) % 6u / 3u));
+	var position = vec4<f32>(uv * 2.0 - 1.0, 1.0, 1.0);
+	return VertOutput(position, uv);
+}
+
+[[stage(fragment)]] fn fragMain(input : VertOutput) -> [[location(0)]] vec4<f32> {
+	return textureSample(inputTexture, inputSampler, input.uv);
+}