- fixed: The scissor rectangle must be clipped to the upper left edge of the screen.

Negative coordinates are treated as "disable scissor", so if some transformation results in something off-screen it needs to be handled before passing it to the backend.

src/common/rendering/hwrenderer/hw_draw2d.cpp

@@ -150,6 +150,9 @@ void Draw2D(F2DDrawer *drawer, FRenderState &state)
 			sciY = screen->ScreenToWindowY(cmd.mScissor[3]);
 			sciW = screen->ScreenToWindowX(cmd.mScissor[2]) - sciX;
 			sciH = screen->ScreenToWindowY(cmd.mScissor[1]) - sciY;
+			// If coordinates turn out negative, clip to sceen here to avoid undefined behavior. 
+			if (sciX < 0) sciW += sciX, sciX = 0;
+			if (sciY < 0) sciH += sciY, sciY = 0;
 		}
 		else
 		{

src/common/textures/texturemanager.h

@@ -11,7 +11,6 @@ class FxAddSub;
 struct BuildInfo;
 class FMultipatchTextureBuilder;
 class FScanner;
-int PalCheck(int tex);
 
 // Texture manager
 class FTextureManager