feat: distance-estimation shading for crisp deep-zoom filaments

tests/shader_valid.rs

@@ -0,0 +1,31 @@
+//! Static validation of the WGSL shaders. `cargo build` does not type-check
+//! WGSL (that happens at pipeline creation), so this parses and validates each
+//! shader with the same `naga` version wgpu uses — catching shader errors
+//! without needing a GPU or a display.
+
+fn validate(name: &str, src: &str) {
+    let module = match naga::front::wgsl::parse_str(src) {
+        Ok(m) => m,
+        Err(e) => panic!("{name}: WGSL parse error:\n{}", e.emit_to_string(src)),
+    };
+    let mut validator = naga::valid::Validator::new(
+        naga::valid::ValidationFlags::all(),
+        naga::valid::Capabilities::all(),
+    );
+    if let Err(e) = validator.validate(&module) {
+        panic!("{name}: WGSL validation error:\n{}", e.emit_to_string(src));
+    }
+}
+
+#[test]
+fn mandelbrot_shader_is_valid() {
+    validate(
+        "mandelbrot.wgsl",
+        include_str!("../src/shaders/mandelbrot.wgsl"),
+    );
+}
+
+#[test]
+fn blit_shader_is_valid() {
+    validate("blit.wgsl", include_str!("../src/shaders/blit.wgsl"));
+}