Fix helicopter intro rendering on wide aspect ratio window tile settings

Source/Amiga/Graphics_Amiga.cpp

@@ -1034,7 +1034,7 @@ void cGraphics_Amiga::Video_Draw_16_Offset(int16 pCx) {
 		uint16 cx;
 		SourceX = 0;
 
-		for (cx = ax; cx < (mSurface->GetWidth() - 32); cx++) {
+		for (cx = ax; cx < 320; cx++) { // Intro art is 320 wide; GetWidth() - 32 is only 320 at the default 352-wide surface.
 
 			DrawPixel(pDs, di, SourceX, SourceY, cx, bx);
 

Source/Briefing.cpp

@@ -479,6 +479,14 @@ void cFodder::Briefing_Intro_Helicopter_Play(const bool pShowHelicopter, eTileTy
     mSurface->clearBuffer();
     mWindow->SetScreenSize(mVersionCurrent->GetScreenSize());
 
+    // Shrink the SDL window to the original 320-wide frame for the
+    // duration of this intro. Gameplay windows are wider when
+    // --columns is raised, but this animation was authored for 320
+    // pixels wide, so rendering it in a wide window stretches it.
+    // SetOriginalRes() resizes the SDL window (by the current scaler);
+    // SetScreenSize() alone only changes the cropped source rectangle.
+    mWindow->SetOriginalRes(mVersionCurrent->GetScreenSize());
+
     if (pTileset >= eTileTypes_Hid)
         pTileset = eTileTypes_Jungle;
 
@@ -502,4 +510,10 @@ void cFodder::Briefing_Intro_Helicopter_Play(const bool pShowHelicopter, eTileTy
     mGraphics->Briefing_Intro_Helicopter_Play(ShowHelicopter, pTileset, Briefing_Get_Mission_Title(), Briefing_Get_Phase_Name());
     mVersionPlatformSwitchDisabled = false;
     mWindow->ToggleVSync(false);
+
+    // Restore the gameplay window (wide again if --columns was raised).
+    // Callers also restore it in Phase_Prepare, but doing it here means
+    // the window is back to gameplay size immediately after the intro,
+    // not only once the next phase starts.
+    Window_UpdateScreenSize();
 }

Source/PC/Graphics_PC.cpp

@@ -748,7 +748,11 @@ void cGraphics_PC::HeliIntro_BlitMaskedAlignedX(tSharedBuffer pSource, int16 pCx
 	const int planeShift = (pCx & 3); // <-- sub-pixel (0..3)
 
 	// first 4-pixel group for pCx
-	uint8* base = mSurface->GetSurfaceBuffer() + mMission_Intro_DrawY + (dx * 4);
+	// mMission_Intro_DrawY is a byte offset into a 352-wide buffer
+	// (row * 352 + 16). Convert it to the current surface width so the
+	// layer starts on the same row/column when the surface is wider.
+	// At the default 352-wide surface this is identical to the old value.
+	uint8* base = mSurface->GetSurfaceBuffer() + ((mMission_Intro_DrawY / 352) * mSurface->GetWidth()) + 16 + (dx * 4);
 
 	++dx;
 
@@ -778,7 +782,7 @@ void cGraphics_PC::HeliIntro_BlitMaskedAlignedX(tSharedBuffer pSource, int16 pCx
 				di += 4;
 			}
 
-			di -= mSurface->GetWidth() - 12 - 16;
+			di -= 324; // 81 groups * 4 bytes. The +GetWidth() below then makes the row advance exactly GetWidth(), instead of a fixed 352.
 			--pDs;
 
 			for (cx = dx; cx > 0; --cx)
@@ -814,7 +818,9 @@ void cGraphics_PC::HeliIntroBlit_OpaqueAlignedX(tSharedBuffer pDsSi, int16 pCx)
 	const int planeShift = (pCx & 3); // <-- the bit the old code discards
 
 	// Base points at the first 4-pixel group for pCx, Y offset unchanged.
-	uint8* base = mSurface->GetSurfaceBuffer() + mMission_Intro_DrawY + (groupX * 4);
+	// See HeliIntro_BlitMaskedAlignedX: convert the 352-wide offset
+	// to the current surface width. Identical at the default width.
+	uint8* base = mSurface->GetSurfaceBuffer() + ((mMission_Intro_DrawY / 352) * mSurface->GetWidth()) + 16 + (groupX * 4);
 
 	++dx;
 
@@ -855,7 +861,7 @@ void cGraphics_PC::HeliIntroBlit_OpaqueAlignedX(tSharedBuffer pDsSi, int16 pCx)
 
 			cx = dx;
 
-			di -= mSurface->GetWidth() - 12 - 16;
+			di -= 324; // 81 groups * 4 bytes. The +GetWidth() below then makes the row advance exactly GetWidth(), instead of a fixed 352.
 			--Ds;
 
 			if (cx & 1)