Crash in W3DShroud::getShroudLevel on map load

[xezon]

Happened once when loading into a level.

y can be negative.

 	generalszh.exe!W3DShroud::getShroudLevel(int x, int y) Line 269	C++	Symbols loaded.
>	generalszh.exe!getRiverVertexDiffuse(W3DShroud * shroud, float x, float y, float shadeR, float shadeG, float shadeB, int diffuse) Line 176	C++	Symbols loaded.
 	generalszh.exe!WaterRenderObjClass::drawRiverWater(PolygonTrigger * pTrig) Line 2861	C++	Symbols loaded.
 	generalszh.exe!WaterRenderObjClass::renderWater() Line 2014	C++	Symbols loaded.
 	generalszh.exe!WaterRenderObjClass::Render(RenderInfoClass & rinfo) Line 1566	C++	Symbols loaded.
 	generalszh.exe!DefaultStaticSortListClass::Render_And_Clear(RenderInfoClass & rinfo) Line 90	C++	Symbols loaded.
 	generalszh.exe!WW3D::Render_And_Clear_Static_Sort_Lists(RenderInfoClass & rinfo) Line 2090	C++	Symbols loaded.
 	generalszh.exe!RTS3DScene::Flush(RenderInfoClass & rinfo) Line 876	C++	Symbols loaded.
 	generalszh.exe!RTS3DScene::Render(RenderInfoClass & rinfo) Line 988	C++	Symbols loaded.
 	generalszh.exe!WW3D::Render(SceneClass * scene, CameraClass * cam, bool clear, bool clearz, const Vector3 & color) Line 988	C++	Symbols loaded.
 	generalszh.exe!RTS3DScene::draw() Line 1763	C++	Symbols loaded.
 	generalszh.exe!SubsystemInterface::DRAW() Line 99	C++	Symbols loaded.
 	generalszh.exe!RTS3DScene::doRender(CameraClass * cam) Line 1748	C++	Symbols loaded.
 	generalszh.exe!W3DView::draw() Line 1872	C++	Symbols loaded.
 	generalszh.exe!SubsystemInterface::DRAW() Line 99	C++	Symbols loaded.
 	generalszh.exe!W3DView::drawView() Line 1836	C++	Symbols loaded.
 	generalszh.exe!Display::drawViews() Line 111	C++	Symbols loaded.
 	generalszh.exe!W3DDisplay::draw() Line 1998	C++	Symbols loaded.
 	generalszh.exe!SubsystemInterface::DRAW() Line 99	C++	Symbols loaded.
 	generalszh.exe!GameClient::update() Line 719	C++	Symbols loaded.
 	generalszh.exe!W3DGameClient::update() Line 94	C++	Symbols loaded.
 	generalszh.exe!SubsystemInterface::UPDATE() Line 73	C++	Symbols loaded.
 	generalszh.exe!GameEngine::update() Line 910	C++	Symbols loaded.
 	generalszh.exe!Win32GameEngine::update() Line 91	C++	Symbols loaded.
 	generalszh.exe!GameEngine::execute() Line 983	C++	Symbols loaded.
 	generalszh.exe!GameMain() Line 55	C++	Symbols loaded.
 	generalszh.exe!WinMain(HINSTANCE__ * hInstance, HINSTANCE__ * hPrevInstance, char * lpCmdLine, int nCmdShow) Line 929	C++	Symbols loaded.
 	generalszh.exe!invoke_main() Line 107	C++	Non-user code. Symbols loaded.
 	generalszh.exe!__scrt_common_main_seh() Line 288	C++	Non-user code. Symbols loaded.
 	generalszh.exe!__scrt_common_main() Line 331	C++	Non-user code. Symbols loaded.
 	generalszh.exe!WinMainCRTStartup(void * __formal) Line 17	C++	Non-user code. Symbols loaded.
 	kernel32.dll!75885d49()	Unknown	Non-user code. Cannot find or open the PDB file.
 	[Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll]		Annotated Frame
 	ntdll.dll!776ee00b()	Unknown	Non-user code. Cannot find or open the PDB file.
 	ntdll.dll!776edf91()	Unknown	Non-user code. Cannot find or open the PDB file.