From f216df7d0f60496304f11572c077f2b275dbdde6 Mon Sep 17 00:00:00 2001
From: Luke Wilde <lukew@serenityos.org>
Date: Wed, 12 Jan 2022 12:10:00 +0000
Subject: [PATCH] LibSoftGPU: Don't render triangle strip if there's less than
 3 vertices

If there's less than 3 vertices, we cannot do triangle strip otherwise
we will go out-of-bounds of the vertices vector.

Required for Half-Life, which sometimes submits 0 vertices for triangle
strip when drawing the electric disks around the pillars in Xen.
---
 Userland/Libraries/LibSoftGPU/Device.cpp | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Userland/Libraries/LibSoftGPU/Device.cpp b/Userland/Libraries/LibSoftGPU/Device.cpp
index 07714c3dca..d2153d69cc 100644
--- a/Userland/Libraries/LibSoftGPU/Device.cpp
+++ b/Userland/Libraries/LibSoftGPU/Device.cpp
@@ -609,6 +609,8 @@ void Device::draw_primitives(PrimitiveType primitive_type, FloatMatrix4x4 const&
         }
     } else if (primitive_type == PrimitiveType::TriangleStrip) {
         Triangle triangle;
+        if (vertices.size() < 3)
+            return;
         for (size_t i = 0; i < vertices.size() - 2; i++) {
             if (i % 2 == 0) {
                 triangle.vertices[0] = vertices.at(i);