Move ProcessDeterministicSpriteGroupRanges into newgrf.cpp

src/newgrf.cpp

@@ -5604,6 +5604,46 @@ static const SpriteGroup *CreateGroupFromGroupID(byte feature, byte setid, byte
 	return new ResultSpriteGroup(spriteset_start, num_sprites);
 }
 
+static void ProcessDeterministicSpriteGroupRanges(const std::vector<DeterministicSpriteGroupRange> &ranges, std::vector<DeterministicSpriteGroupRange> &ranges_out, const SpriteGroup *default_group)
+{
+	/* Sort ranges ascending. When ranges overlap, this may required clamping or splitting them */
+	std::vector<uint32> bounds;
+	for (uint i = 0; i < ranges.size(); i++) {
+		bounds.push_back(ranges[i].low);
+		if (ranges[i].high != UINT32_MAX) bounds.push_back(ranges[i].high + 1);
+	}
+	std::sort(bounds.begin(), bounds.end());
+	bounds.erase(std::unique(bounds.begin(), bounds.end()), bounds.end());
+
+	std::vector<const SpriteGroup *> target;
+	for (uint j = 0; j < bounds.size(); ++j) {
+		uint32 v = bounds[j];
+		const SpriteGroup *t = default_group;
+		for (uint i = 0; i < ranges.size(); i++) {
+			if (ranges[i].low <= v && v <= ranges[i].high) {
+				t = ranges[i].group;
+				break;
+			}
+		}
+		target.push_back(t);
+	}
+	assert(target.size() == bounds.size());
+
+	for (uint j = 0; j < bounds.size(); ) {
+		if (target[j] != default_group) {
+			DeterministicSpriteGroupRange &r = ranges_out.emplace_back();
+			r.group = target[j];
+			r.low = bounds[j];
+			while (j < bounds.size() && target[j] == r.group) {
+				j++;
+			}
+			r.high = j < bounds.size() ? bounds[j] - 1 : UINT32_MAX;
+		} else {
+			j++;
+		}
+	}
+}
+
 /* Action 0x02 */
 static void NewSpriteGroup(ByteReader *buf)
 {