From 5acf324fdf71f48f834aba9fa9c105664e4a061f Mon Sep 17 00:00:00 2001
From: Morilli <35152647+Morilli@users.noreply.github.com>
Date: Fri, 20 Sep 2024 18:26:15 +0200
Subject: [PATCH] attempt to fix GPGX aspect ratio

see #4042, not sure if this is fully correct yet
---
 .../Consoles/Sega/gpgx64/GPGX.IVideoProvider.cs      | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IVideoProvider.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IVideoProvider.cs
index 86face6854..257623b19e 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IVideoProvider.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/gpgx64/GPGX.IVideoProvider.cs
@@ -30,6 +30,14 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 			var widthHasOverscan = (_syncSettings.Overscan & LibGPGX.InitSettings.OverscanType.Horizontal) != 0;
 			var heightHasOverscan = (_syncSettings.Overscan & LibGPGX.InitSettings.OverscanType.Vertical) != 0;
 			var isPal = Region == DisplayType.PAL;
+			bool isVdpPal = _syncSettings.ForceVDP switch
+			{
+				LibGPGX.ForceVDP.NTSC => false,
+				LibGPGX.ForceVDP.PAL => true,
+				_ => isPal
+			};
+			double videoSampleRate = isVdpPal ? 14750000.0 : 135000000.0 / 11.0;
+			int clockRate = isPal ? 53203424 : 53693175;
 
 			if (SystemId == VSystemID.Raw.GEN)
 			{
@@ -37,6 +45,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 				VirtualHeight = 224;
 				VirtualWidth += widthHasOverscan ? 28 : 0;
 				VirtualHeight += heightHasOverscan ? (isPal ? 48 : 0) + 16 : 0;
+
+				VirtualWidth = (int)(VirtualWidth * 4.0 * videoSampleRate / clockRate);
 			}
 			else
 			{
@@ -53,6 +63,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 					VirtualWidth += widthHasOverscan ? 28 : 0;
 					VirtualHeight += heightHasOverscan ? (isPal ? 96 : 48) : 0;
 				}
+
+				VirtualWidth = (int)(VirtualWidth * 5.0 * videoSampleRate / clockRate);
 			}
 		}