From 37ec8d030f500f2b7075f4b11930abe2e3531486 Mon Sep 17 00:00:00 2001
From: Gleb Mazovetskiy <glex.spb@gmail.com>
Date: Tue, 1 Nov 2022 12:47:50 +0000
Subject: [PATCH] Fix loading screen glitches

---
 Source/diablo.cpp   | 10 +++++++++-
 Source/interfac.cpp | 11 +++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Source/diablo.cpp b/Source/diablo.cpp
index 15e616dda..459fb9a64 100644
--- a/Source/diablo.cpp
+++ b/Source/diablo.cpp
@@ -704,8 +704,16 @@ void GameEventHandler(const SDL_Event &event, uint16_t modState)
 			LastMouseButtonAction = MouseActionType::None;
 			sgbMouseDown = CLICK_NONE;
 			ShowProgress(GetCustomEvent(event.type));
+
 			RedrawEverything();
-			DrawAndBlit();
+			if (!HeadlessMode) {
+				while (IsRedrawEverything()) {
+					// In direct rendering mode with double/triple buffering, we need
+					// to prepare all buffers before fading in.
+					DrawAndBlit();
+				}
+			}
+
 			LoadPWaterPalette();
 			if (gbRunGame)
 				PaletteFadeIn(8);
diff --git a/Source/interfac.cpp b/Source/interfac.cpp
index d5203e396..bd1ded376 100644
--- a/Source/interfac.cpp
+++ b/Source/interfac.cpp
@@ -467,6 +467,17 @@ void ShowProgress(interface_mode uMsg)
 	if (!HeadlessMode) {
 		assert(ghMainWnd);
 
+		if (RenderDirectlyToOutputSurface && PalSurface != nullptr) {
+			// Ensure that all back buffers have the full progress bar.
+			const void *initialPixels = PalSurface->pixels;
+			do {
+				DrawCutsceneForeground();
+				if (DiabloUiSurface() == PalSurface)
+					BltFast(nullptr, nullptr);
+				RenderPresent();
+			} while (PalSurface->pixels != initialPixels);
+		}
+
 		PaletteFadeOut(8);
 	}