From 0e6dd28573e4668e41642c335d740aed46b4da14 Mon Sep 17 00:00:00 2001
From: terminx <terminx@1a8010ca-5511-0410-912e-c29ae57300e0>
Date: Mon, 4 Mar 2019 23:49:03 +0000
Subject: [PATCH] Patch from Nuke.YKT to clip Polymost spans to screen borders

git-svn-id: https://svn.eduke32.com/eduke32@7390 1a8010ca-5511-0410-912e-c29ae57300e0
---
 source/build/src/polymost.cpp | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/source/build/src/polymost.cpp b/source/build/src/polymost.cpp
index 673df626d..21702797a 100644
--- a/source/build/src/polymost.cpp
+++ b/source/build/src/polymost.cpp
@@ -3572,11 +3572,23 @@ static void polymost_domost(float x0, float y0, float x1, float y1)
         return;
     }
 
-    vec2f_t const dm0 = { x0, y0 };
-    vec2f_t const dm1 = { x1, y1 };
+    vec2f_t dm0 = { x0, y0 };
+    vec2f_t dm1 = { x1, y1 };
 
     float const slop = (dm1.y - dm0.y) / (dm1.x - dm0.x);
 
+    if (dm0.x < xbl)
+    {
+        dm0.y += slop*(xbl-dm0.x);
+        dm0.x = xbl;
+    }
+
+    if (dm1.x > xbr)
+    {
+        dm1.y += slop*(xbr-dm1.x);
+        dm1.x = xbr;
+    }
+
     drawpoly_alpha = 0.f;
     drawpoly_blend = 0;