Remove duplicate code in DoLighting

Source/engine/displacement.hpp

@@ -125,6 +125,18 @@ struct Displacement {
 		return { (deltaY - deltaX) * 32, (deltaY + deltaX) * -16 };
 	}
 
+	constexpr Displacement Rotate(int quadrants)
+	{
+		constexpr int Sines[] = { 0, 1, 0, -1 };
+
+		quadrants = (quadrants % 4 + 4) % 4;
+
+		int sine = Sines[quadrants];
+		int cosine = Sines[(quadrants + 1) % 4];
+
+		return Displacement { deltaX * cosine - deltaY * sine, deltaX * sine + deltaY * cosine };
+	}
+
 private:
 	static constexpr Displacement fromDirection(Direction direction)
 	{

Source/lighting.cpp

@@ -571,60 +571,24 @@ void DoLighting(Point position, int nRadius, int lnum)
 		}
 	}
 
-	int mult = xoff + 8 * yoff;
-	for (int y = 0; y < minY; y++) {
-		for (int x = 1; x < maxX; x++) {
-			int radiusBlock = lightblock[mult][y][x];
-			if (radiusBlock < 128) {
-				Point temp = position + Displacement { x, y };
-				int8_t v = lightradius[nRadius][radiusBlock];
-				if (InDungeonBounds(temp))
-					if (v < GetLight(temp))
-						SetLight(temp, v);
-			}
-		}
-	}
-	RotateRadius(&xoff, &yoff, &distX, &distY, &lightX, &lightY, &blockX, &blockY);
-	mult = xoff + 8 * yoff;
-	for (int y = 0; y < maxY; y++) {
-		for (int x = 1; x < maxX; x++) {
-			int radiusBlock = lightblock[mult][y + blockY][x + blockX];
-			if (radiusBlock < 128) {
-				Point temp = position + Displacement { y, -x };
-				int8_t v = lightradius[nRadius][radiusBlock];
-				if (InDungeonBounds(temp))
-					if (v < GetLight(temp))
-						SetLight(temp, v);
-			}
-		}
-	}
-	RotateRadius(&xoff, &yoff, &distX, &distY, &lightX, &lightY, &blockX, &blockY);
-	mult = xoff + 8 * yoff;
-	for (int y = 0; y < maxY; y++) {
-		for (int x = 1; x < minX; x++) {
-			int radiusBlock = lightblock[mult][y + blockY][x + blockX];
-			if (radiusBlock < 128) {
-				Point temp = position - Displacement { x, y };
-				int8_t v = lightradius[nRadius][radiusBlock];
-				if (InDungeonBounds(temp))
-					if (v < GetLight(temp))
-						SetLight(temp, v);
-			}
-		}
-	}
-	RotateRadius(&xoff, &yoff, &distX, &distY, &lightX, &lightY, &blockX, &blockY);
-	mult = xoff + 8 * yoff;
-	for (int y = 0; y < minY; y++) {
-		for (int x = 1; x < minX; x++) {
-			int radiusBlock = lightblock[mult][y + blockY][x + blockX];
-			if (radiusBlock < 128) {
-				Point temp = position + Displacement { -y, x };
+	for (int i = 0; i < 4; i++) {
+		int mult = xoff + 8 * yoff;
+		int yBound = i > 0 && i < 3 ? maxY : minY;
+		int xBound = i < 2 ? maxX : minX;
+		for (int y = 0; y < yBound; y++) {
+			for (int x = 1; x < xBound; x++) {
+				int radiusBlock = lightblock[mult][y + blockY][x + blockX];
+				if (radiusBlock >= 128)
+					continue;
+				Point temp = position + (Displacement { x, y }).Rotate(-i);
 				int8_t v = lightradius[nRadius][radiusBlock];
-				if (InDungeonBounds(temp))
-					if (v < GetLight(temp))
-						SetLight(temp, v);
+				if (!InDungeonBounds(temp))
+					continue;
+				if (v < GetLight(temp))
+					SetLight(temp, v);
 			}
 		}
+		RotateRadius(&xoff, &yoff, &distX, &distY, &lightX, &lightY, &blockX, &blockY);
 	}
 }