/// <summary>
/// Calculates the length of the road for the given atom, taking its position and environment into account. This
/// method is invoked by each <see cref="RoadAtom"/> during its production, in order to find out its length.
/// </summary>
/// <returns>The road length.</returns>
/// <param name="currentAtom">Current atom.</param>
/// <param name="gen">City generator.</param>
public virtual float CalculateRoadLength(RoadAtom currentAtom, CityGenerator gen)
{
// Calculate how much the population density influences road length (the less population, the longer the road)
float populationLengthFactor = 1f - gen.DensityAt(currentAtom.Node.position);
// Calculate how much the slope of the road influences its length (the steeper, the shorter)
float elevationLengthFactor = Mathf.Abs(gen.ElevationAt(currentAtom.Node.position) -
gen.ElevationAt(currentAtom.Node.position + currentAtom.Forward));
elevationLengthFactor = 1f - Mathf.Clamp01(gen.slopeExaggeration * elevationLengthFactor);
// Multiply them to get the final length factor. Basically the elevation factor should only influence the
// population factor when the road is very steep, in other cases it should be close to 1.
float lengthFactor = populationLengthFactor * elevationLengthFactor;
// Calculate the road length
return gen.minimumRoadLength + lengthFactor * (gen.maximumRoadLength - gen.minimumRoadLength);
}
public override List<RoadAtom> SpawnRoads(BranchAtom currentAtom, CityGenerator gen)
{
List<RoadAtom> production = new List<RoadAtom>();
if (currentAtom.Creator != null) {
// Get the orientation of the "parent" road (the one we're continuing in this production)
MapNode toNode = currentAtom.Node;
MapNode fromNode = currentAtom.Node.edges[0].FromNode;
Vector3 parentDirection = (toNode.position - fromNode.position).normalized;
// Get the elevation at the current point
float currentElevation = gen.ElevationAt(currentAtom.Node.position);
// Create three roads: left, right and straight with regard to the "parent" road's direction
float[] angles = new float[] { -90f, 0f, 90f };
foreach (float angle in angles) {
// Rotate the direction vector to get the direction we'll probe in
Vector3 roadDirection = Quaternion.Euler(0f, angle, 0f) * parentDirection;
// Probe elevations around the given direction and get the direction of the road which is least steep
roadDirection = LeastSteepDirection(currentAtom.Node.position, roadDirection, currentElevation, gen);
// Create a new RoadAtom with the given road direction
RoadAtom roadAtom = new RoadAtom(roadDirection, currentAtom.Node, Rule.Type.Rectangular);
// Add it to the production
production.Add(roadAtom);
}
} else {
// This is the axiom, just spawn roads in all directions
production.Add(new RoadAtom(Vector3.forward, currentAtom.Node, Rule.Type.Rectangular));
production.Add(new RoadAtom(Vector3.back, currentAtom.Node, Rule.Type.Rectangular));
production.Add(new RoadAtom(Vector3.left, currentAtom.Node, Rule.Type.Rectangular));
production.Add(new RoadAtom(Vector3.right, currentAtom.Node, Rule.Type.Rectangular));
}
return production;
}
