From 685d72b6d7329c19e842586ea4a17e056eb40729 Mon Sep 17 00:00:00 2001
From: NepDisk <16447892+NepDisk@users.noreply.github.com>
Date: Wed, 11 Sep 2024 08:30:20 -0400
Subject: [PATCH] Clamp rover->alpha-1 to prevent overflow

Thanks Alug!
---
 src/hardware/hw_main.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 72e31e1b5..f35b80cd5 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -1820,7 +1820,7 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 						if (rover->alpha < 256 || rover->blend)
 						{
 							blendmode = HWR_GetBlendModeFlag(rover->blend);
-							Surf.PolyColor.s.alpha = (UINT8)(rover->alpha-1);
+							Surf.PolyColor.s.alpha = (UINT8)(max(0, min(rover->alpha, 255)));
 						}
 					}
 
@@ -1946,7 +1946,7 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 						if (rover->alpha < 256 || rover->blend)
 						{
 							blendmode = HWR_GetBlendModeFlag(rover->blend);
-							Surf.PolyColor.s.alpha = (UINT8)(rover->alpha-1);
+							Surf.PolyColor.s.alpha = (UINT8)(max(0, min(rover->alpha, 255)));
 						}
 					}
 
@@ -3262,7 +3262,7 @@ static void HWR_Subsector(size_t num)
 										   false,
 					                       *rover->bottomheight,
 					                       *gl_frontsector->lightlist[light].lightlevel,
-					                       rover->alpha-1, rover->master->frontsector, blendmode,
+					                       max(0, min(rover->alpha, 255)), rover->master->frontsector, blendmode,
 					                       false, *gl_frontsector->lightlist[light].extra_colormap);
 				}
 				else
@@ -3310,7 +3310,7 @@ static void HWR_Subsector(size_t num)
 											true,
 					                        *rover->topheight,
 					                        *gl_frontsector->lightlist[light].lightlevel,
-					                        rover->alpha-1, rover->master->frontsector, blendmode,
+					                        max(0, min(rover->alpha, 255)), rover->master->frontsector, blendmode,
 					                        false, *gl_frontsector->lightlist[light].extra_colormap);
 				}
 				else