Calculate and show the required speed at all points of the route

native/route_search.cpp

@@ -54,6 +54,7 @@ struct JSNodeInfo {
 	float positionZ;
 	float distanceFromStart;
 	float currentSpeed;
+	float requiredSpeed;
 };
 
 struct JSSearchResult {
@@ -459,7 +460,36 @@ JSSearchResult findAllPathsFromPointJS(int startingNode, float minimumSpeed, flo
 	return searchResult;
 }
 
-std::vector<JSNodeInfo> getPathJS(uint32_t startingNode, uint32_t endNode) {
+float calculateRequiredSpeed(float endSpeed, float horizontalDistance, float heightDifference, float dragCoefficient) {
+	// The bike will never reach faster speeds than terminal velocity in free fall
+	float maximumSpeed = sqrt(GRAVITY_ACCELERATION / dragCoefficient);
+
+	// First, check if we'll reach the required speed no matter what
+	if (calculate_speed(0.00001, horizontalDistance, heightDifference, 0.0, maximumSpeed, dragCoefficient) >= endSpeed) {
+		return 0.0;
+	}
+
+	// Divide and conquer
+	float numerator = 0;
+	float denominator = 0.5;
+	float foundEndSpeed = -100.0;
+	do {
+		numerator *= 2;
+		denominator *= 2;
+		if (foundEndSpeed > endSpeed) {
+			numerator -= 1;
+		} else {
+			numerator += 1;
+		}
+		foundEndSpeed = calculate_speed(maximumSpeed * numerator / denominator, horizontalDistance, heightDifference, 0.01, 100.0, dragCoefficient);
+	} while (fabs(foundEndSpeed - endSpeed) > 0.013);
+
+	float requiredSpeed = maximumSpeed * numerator / denominator;
+
+	return requiredSpeed;
+}
+
+std::vector<JSNodeInfo> getPathJS(uint32_t startingNode, uint32_t endNode, float dragCoefficient) {
 	std::vector<JSNodeInfo> path;
 
 	if (lastSearchResult.startingNode != startingNode) {
@@ -496,6 +526,34 @@ std::vector<JSNodeInfo> getPathJS(uint32_t startingNode, uint32_t endNode) {
 		path.push_back(nodeInfo);
 	}
 
+	float currentRequiredSpeed = -1.0;
+	for (auto it = path.rbegin(); it != path.rend(); it++) {
+		if (currentRequiredSpeed <= -1.0) {
+			it->requiredSpeed = 1.0;
+			currentRequiredSpeed = 1.0;
+		} else {
+			uint32_t currentNodeId = it->nodeId;
+			RoadNode currentNode = set.roadNodes[currentNodeId];
+			uint32_t nextNodeId = (it - 1)->nodeId;
+			RoadNode nextNode = set.roadNodes[nextNodeId];
+
+			float heightDifference = nextNode.position_z - currentNode.position_z;
+
+			Connection neighbours[10];
+			int numberOfNeighbours = 0;
+			getNeighbourConnections(currentNode, neighbours, numberOfNeighbours);
+			for (int i = 0; i < numberOfNeighbours; i++) {
+				Connection neighbour = neighbours[i];
+				if (neighbour.connected_point_number == nextNodeId) {
+					float horizontalDistance = neighbour.distance;
+					currentRequiredSpeed = calculateRequiredSpeed(currentRequiredSpeed, horizontalDistance, heightDifference, dragCoefficient);
+					it->requiredSpeed = currentRequiredSpeed;
+					break;
+				}
+			}
+		}
+	}
+
 	return path;
 }
 
@@ -761,6 +819,7 @@ EMSCRIPTEN_BINDINGS(my_module) {
 		.property("positionY", &JSNodeInfo::positionY)
 		.property("positionZ", &JSNodeInfo::positionZ)
 		.property("currentSpeed", &JSNodeInfo::currentSpeed)
+		.property("requiredSpeed", &JSNodeInfo::requiredSpeed)
 		.property("distanceFromStart", &JSNodeInfo::distanceFromStart);
 
 	emscripten::class_<JSSearchResult>("SearchResult")