perf(terrain): Hoist global light ray computation out of per-vertex loop

In HeightMapRenderObjClass::updateVB, the light ray directions were
recomputed from TheGlobalData->m_terrainLightPos for every terrain
quad in the nested i,j loops. These values are constant for the
entire update region, so move the computation before the loops.

Eliminates (width * height - 1) redundant recomputations per update
tile (typically 255 iterations saved for a 16x16 tile).

Author: Cellcote

Core/GameEngineDevice/Source/W3DDevice/GameClient/HeightMap.cpp

@@ -327,6 +327,12 @@ Int HeightMapRenderObjClass::updateVB(DX8VertexBufferClass	*pVB, VERTEX_FORMAT *
 		// At the bottom, we will copy the final vertex data for one cell into the
 		// hardware vertex buffer.
 
+		for (Int lightIndex=0; lightIndex < TheGlobalData->m_numGlobalLights; lightIndex++)
+		{
+			lightPos=&TheGlobalData->m_terrainLightPos[lightIndex];
+			lightRay[lightIndex].Set(-lightPos->x,-lightPos->y,	-lightPos->z);
+		}
+
 		for (j=y0; j<y1; j++)
 		{
 			VERTEX_FORMAT *vb = vBase;
@@ -362,12 +368,6 @@ Int HeightMapRenderObjClass::updateVB(DX8VertexBufferClass	*pVB, VERTEX_FORMAT *
 				pMap->getUVData(mapX, mapY, U, V);
 				pMap->getAlphaUVData(mapX, mapY, UA, VA, alpha, &flipForBlend);
 
-				for (Int lightIndex=0; lightIndex < TheGlobalData->m_numGlobalLights; lightIndex++)
-				{
-					lightPos=&TheGlobalData->m_terrainLightPos[lightIndex];
-					lightRay[lightIndex].Set(-lightPos->x,-lightPos->y,	-lightPos->z);
-				}
-
 				//top-left sample
 				l2r.Set(2*MAP_XY_FACTOR,0,MAP_HEIGHT_SCALE*(pMap->getDisplayHeight(mapX+cellOffset, mapY) - pMap->getDisplayHeight(un0, mapY)));
 				n2f.Set(0,2*MAP_XY_FACTOR,MAP_HEIGHT_SCALE*(pMap->getDisplayHeight(mapX, (mapY+cellOffset)) - pMap->getDisplayHeight(mapX, vn0)));