From 0f1df90d904925e7808b3e4c28ea0bdad6c3ed4c Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Mon, 19 Apr 2021 23:00:20 +0200
Subject: [PATCH] Tesselator: ignore non-positive clip rectangles

Closes https://github.com/emilk/egui/issues/328
---
 emath/src/rect.rs         | 3 +++
 epaint/src/tessellator.rs | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/emath/src/rect.rs b/emath/src/rect.rs
index 3584a1859..7875cd5ca 100644
--- a/emath/src/rect.rs
+++ b/emath/src/rect.rs
@@ -304,16 +304,19 @@ impl Rect {
     }
 
     /// `min.x <= max.x && min.y <= max.y`.
+    #[inline(always)]
     pub fn is_non_negative(&self) -> bool {
         self.min.x <= self.max.x && self.min.y <= self.max.y
     }
 
     /// True if all members are also finite.
+    #[inline(always)]
     pub fn is_finite(&self) -> bool {
         self.min.is_finite() && self.max.is_finite()
     }
 
     /// True if any member is NaN.
+    #[inline(always)]
     pub fn any_nan(self) -> bool {
         self.min.any_nan() || self.max.any_nan()
     }
diff --git a/epaint/src/tessellator.rs b/epaint/src/tessellator.rs
index f560ec6df..135e219f3 100644
--- a/epaint/src/tessellator.rs
+++ b/epaint/src/tessellator.rs
@@ -742,6 +742,10 @@ pub fn tessellate_shapes(
     let mut clipped_meshes: Vec<ClippedMesh> = Vec::default();
 
     for ClippedShape(clip_rect, shape) in shapes {
+        if !clip_rect.is_non_negative() {
+            continue; // skip empty clip rectangles
+        }
+
         let start_new_mesh = match clipped_meshes.last() {
             None => true,
             Some(cm) => cm.0 != clip_rect || cm.1.texture_id != shape.texture_id(),