Port example 03

lib/ui_renderer_wgpu/src/lib.rs

@@ -2135,7 +2135,11 @@ fn push_clip_state(stack: &mut Vec<ActiveClip>, active: &mut ActiveClip, region:
         active.rounded = Some((region.rect, region.radius));
     }
     active.rect = if active.rect_active {
-        intersect_rects(active.rect, Some(region.rect))
+        if active.rect.is_none() {
+            None
+        } else {
+            intersect_rects(active.rect, Some(region.rect))
+        }
     } else {
         Some(region.rect)
     };
@@ -2397,4 +2401,47 @@ mod tests {
             .is_none()
         );
     }
+
+    #[test]
+    fn deeper_nested_clip_cannot_revive_empty_parent_clip() {
+        let mut clip_stack = Vec::new();
+        let mut active_clip = ActiveClip::default();
+
+        push_clip_state(
+            &mut clip_stack,
+            &mut active_clip,
+            ClipRegion {
+                rect: Rect::new(0.0, 0.0, 100.0, 100.0),
+                radius: 0.0,
+            },
+        );
+        push_clip_state(
+            &mut clip_stack,
+            &mut active_clip,
+            ClipRegion {
+                rect: Rect::new(150.0, 150.0, 50.0, 50.0),
+                radius: 12.0,
+            },
+        );
+        push_clip_state(
+            &mut clip_stack,
+            &mut active_clip,
+            ClipRegion {
+                rect: Rect::new(160.0, 160.0, 24.0, 12.0),
+                radius: 8.0,
+            },
+        );
+
+        assert!(active_clip.rect_active);
+        assert_eq!(active_clip.rect, None);
+        assert!(
+            build_text_vertices(
+                Point::new(162.0, 162.0),
+                UiSize::new(16.0, 8.0),
+                UiSize::new(400.0, 400.0),
+                active_clip,
+            )
+            .is_none()
+        );
+    }
 }