sparse_strips: Fix clipping for inverse blurred_rounded_rects

sparse_strips/vello_cpu/src/render.rs

@@ -420,8 +420,12 @@ impl RenderContext {
         // is not cut off.
         // The impulse response of a gaussian filter is infinite.
         // For performance reason we cut off the filter at some extent where the response is close to zero.
-        let kernel_size = 2.5 * std_dev;
-        let inflated_rect = rect.inflate(f64::from(kernel_size), f64::from(kernel_size));
+        let inflated_rect = if invert {
+            rect.inflate(rect.origin().x.abs(), rect.origin().y.abs())
+        } else {
+            let kernel_size = 2.5 * std_dev;
+            rect.inflate(f64::from(kernel_size), f64::from(kernel_size))
+        };
         let transform = self.effective_path_transform();
         let paint_transform = self.effective_paint_transform();
 

sparse_strips/vello_hybrid/src/scene.rs

@@ -771,8 +771,12 @@ impl Scene {
                 invert,
             };
 
-            let kernel_size = 2.5 * std_dev;
-            let inflated_rect = rect.inflate(f64::from(kernel_size), f64::from(kernel_size));
+            let inflated_rect = if invert {
+                rect.inflate(rect.origin().x.abs(), rect.origin().y.abs())
+            } else {
+                let kernel_size = 2.5 * std_dev;
+                rect.inflate(f64::from(kernel_size), f64::from(kernel_size))
+            };
             let transform = ctx.render_state.transform * ctx.render_state.paint_transform;
             let paint =
                 blurred_rect.encode_into(&mut ctx.encoded_paints.borrow_mut(), transform, None);

sparse_strips/vello_sparse_tests/tests/blurred_rounded_rect.rs

@@ -70,6 +70,11 @@ fn inverse_rect_with(ctx: &mut impl Renderer, radius: f32, std_dev: f32, affine:
     ctx.fill_blurred_rounded_rect(&rect, radius, std_dev, true);
 }
 
+#[vello_test]
+fn inverse_blurred_rounded_rect_zero_with_radius(ctx: &mut impl Renderer) {
+    inverse_rect_with(ctx, 10.0, 0.0, Affine::IDENTITY);
+}
+
 #[vello_test]
 fn inverse_blurred_rounded_rect_small_std_dev(ctx: &mut impl Renderer) {
     inverse_rect_with(ctx, 0.0, 5.0, Affine::IDENTITY);