318 lines
12 KiB
C#
318 lines
12 KiB
C#
using SpaceGame.Simulation.Api.Data;
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namespace SpaceGame.Simulation.Api.Simulation;
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public sealed partial class SimulationEngine
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{
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private static Vector3 ComputePlanetPosition(PlanetDefinition planet, float timeSeconds)
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{
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var eccentricity = Math.Clamp(planet.OrbitEccentricity, 0f, 0.85f);
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var meanAnomaly = DegreesToRadians(planet.OrbitPhaseAtEpoch) + (timeSeconds * planet.OrbitSpeed);
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var eccentricAnomaly = meanAnomaly
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+ (eccentricity * MathF.Sin(meanAnomaly))
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+ (0.5f * eccentricity * eccentricity * MathF.Sin(2f * meanAnomaly));
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var semiMajorAxis = SimulationUnits.AuToKilometers(planet.OrbitRadius);
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var semiMinorAxis = semiMajorAxis * MathF.Sqrt(MathF.Max(1f - (eccentricity * eccentricity), 0.05f));
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var local = new Vector3(
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semiMajorAxis * (MathF.Cos(eccentricAnomaly) - eccentricity),
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0f,
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semiMinorAxis * MathF.Sin(eccentricAnomaly));
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local = RotateAroundY(local, DegreesToRadians(planet.OrbitArgumentOfPeriapsis));
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local = RotateAroundX(local, DegreesToRadians(planet.OrbitInclination));
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local = RotateAroundY(local, DegreesToRadians(planet.OrbitLongitudeOfAscendingNode));
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return local;
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}
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private static Vector3 ComputeMoonOffset(PlanetDefinition planet, int moonIndex, float timeSeconds)
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{
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var orbitRadius = ComputeMoonOrbitRadius(planet, moonIndex);
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var speed = ComputeMoonOrbitSpeed(planet, moonIndex);
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var phase = HashUnit($"{planet.Label}:{moonIndex}:phase") * MathF.PI * 2f;
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var inclination = DegreesToRadians((HashUnit($"{planet.Label}:{moonIndex}:inclination") - 0.5f) * 28f);
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var ascendingNode = DegreesToRadians(HashUnit($"{planet.Label}:{moonIndex}:node") * 360f);
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var angle = phase + (timeSeconds * speed);
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var local = new Vector3(
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MathF.Cos(angle) * orbitRadius,
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0f,
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MathF.Sin(angle) * orbitRadius);
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local = RotateAroundX(local, inclination);
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local = RotateAroundY(local, ascendingNode);
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return local;
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}
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private static float ComputeMoonOrbitRadius(PlanetDefinition planet, int moonIndex)
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{
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var spacing = planet.Size * 1.4f;
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var variance = HashUnit($"{planet.Label}:{moonIndex}:radius") * planet.Size * 0.9f;
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return (planet.Size * 1.8f) + (moonIndex * spacing) + variance;
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}
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private static float ComputeMoonOrbitSpeed(PlanetDefinition planet, int moonIndex)
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{
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var radius = ComputeMoonOrbitRadius(planet, moonIndex);
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return 0.9f / MathF.Sqrt(MathF.Max(radius, 1f)) + (moonIndex * 0.003f);
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}
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private static float ComputeResourceNodeOrbitSpeed(ResourceNodeRuntime node)
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{
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var baseSpeed = 0.24f;
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return baseSpeed / MathF.Sqrt(MathF.Max(node.OrbitRadius / 180000f, 0.45f));
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}
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private static Vector3 ComputeResourceNodeOffset(ResourceNodeRuntime node, float timeSeconds)
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{
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var angle = node.OrbitPhase + (timeSeconds * ComputeResourceNodeOrbitSpeed(node));
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var orbit = new Vector3(
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MathF.Cos(angle) * node.OrbitRadius,
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0f,
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MathF.Sin(angle) * node.OrbitRadius);
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return RotateAroundX(orbit, node.OrbitInclination);
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}
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private static IEnumerable<LagrangePointPlacement> EnumeratePlanetLagrangePoints(
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Vector3 planetPosition,
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PlanetDefinition planet)
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{
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var radial = NormalizeOrFallback(planetPosition, new Vector3(1f, 0f, 0f));
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var tangential = new Vector3(-radial.Z, 0f, radial.X);
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var orbitRadiusKm = MathF.Sqrt(planetPosition.X * planetPosition.X + planetPosition.Z * planetPosition.Z);
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var offset = ComputePlanetLocalLagrangeOffset(orbitRadiusKm, planet);
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var triangularAngle = MathF.PI / 3f;
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yield return new LagrangePointPlacement("L1", Add(planetPosition, Scale(radial, -offset)));
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yield return new LagrangePointPlacement("L2", Add(planetPosition, Scale(radial, offset)));
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yield return new LagrangePointPlacement("L3", Scale(radial, -orbitRadiusKm));
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yield return new LagrangePointPlacement(
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"L4",
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Add(
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Scale(radial, orbitRadiusKm * MathF.Cos(triangularAngle)),
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Scale(tangential, orbitRadiusKm * MathF.Sin(triangularAngle))));
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yield return new LagrangePointPlacement(
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"L5",
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Add(
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Scale(radial, orbitRadiusKm * MathF.Cos(triangularAngle)),
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Scale(tangential, -orbitRadiusKm * MathF.Sin(triangularAngle))));
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}
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private static float ComputePlanetLocalLagrangeOffset(float orbitRadiusKm, PlanetDefinition planet)
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{
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var planetMassProxy = EstimatePlanetMassRatio(planet);
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var hillLikeOffset = orbitRadiusKm * MathF.Cbrt(MathF.Max(planetMassProxy / 3f, 1e-9f));
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var minimumOffset = MathF.Max(planet.Size * 4f, 25000f);
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return MathF.Max(minimumOffset, hillLikeOffset);
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}
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private static float EstimatePlanetMassRatio(PlanetDefinition planet)
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{
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var earthRadiusRatio = MathF.Max(planet.Size / 6371f, 0.05f);
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var densityFactor = planet.PlanetType switch
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{
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"gas-giant" => 0.24f,
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"ice-giant" => 0.18f,
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"oceanic" => 0.95f,
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"ice" => 0.7f,
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_ => 1f,
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};
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var earthMasses = MathF.Pow(earthRadiusRatio, 3f) * densityFactor;
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return earthMasses / 332_946f;
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}
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private static Vector3 NormalizeOrFallback(Vector3 value, Vector3 fallback)
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{
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var length = MathF.Sqrt(value.LengthSquared());
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if (length <= 0.0001f)
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{
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return fallback;
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}
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return value.Divide(length);
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}
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private static Vector3 RotateAroundX(Vector3 value, float angle)
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{
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var cos = MathF.Cos(angle);
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var sin = MathF.Sin(angle);
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return new Vector3(
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value.X,
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(value.Y * cos) - (value.Z * sin),
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(value.Y * sin) + (value.Z * cos));
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}
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private static Vector3 RotateAroundY(Vector3 value, float angle)
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{
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var cos = MathF.Cos(angle);
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var sin = MathF.Sin(angle);
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return new Vector3(
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(value.X * cos) + (value.Z * sin),
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value.Y,
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(-value.X * sin) + (value.Z * cos));
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}
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private static Vector3 Add(Vector3 left, Vector3 right) => new(left.X + right.X, left.Y + right.Y, left.Z + right.Z);
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private static Vector3 Scale(Vector3 value, float scalar) => new(value.X * scalar, value.Y * scalar, value.Z * scalar);
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private static float DegreesToRadians(float degrees) => degrees * (MathF.PI / 180f);
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private static float HashUnit(string input)
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{
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unchecked
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{
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var hash = 2166136261u;
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foreach (var character in input)
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{
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hash ^= character;
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hash *= 16777619u;
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}
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return (hash & 0x00FFFFFF) / (float)0x01000000;
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}
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}
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private void UpdateOrbitalState(SimulationWorld world)
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{
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var worldTimeSeconds = (float)world.OrbitalTimeSeconds;
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var spatialNodesById = world.SpatialNodes.ToDictionary(node => node.Id, StringComparer.Ordinal);
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foreach (var system in world.Systems)
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{
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var starNodeId = $"node-{system.Definition.Id}-star";
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if (spatialNodesById.TryGetValue(starNodeId, out var starNode))
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{
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starNode.Position = Vector3.Zero;
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}
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for (var planetIndex = 0; planetIndex < system.Definition.Planets.Count; planetIndex += 1)
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{
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var planet = system.Definition.Planets[planetIndex];
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var planetNodeId = $"node-{system.Definition.Id}-planet-{planetIndex + 1}";
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if (!spatialNodesById.TryGetValue(planetNodeId, out var planetNode))
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{
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continue;
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}
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var planetPosition = ComputePlanetPosition(planet, worldTimeSeconds);
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planetNode.Position = planetPosition;
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foreach (var lagrange in EnumeratePlanetLagrangePoints(planetPosition, planet))
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{
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var lagrangeId = $"node-{system.Definition.Id}-planet-{planetIndex + 1}-{lagrange.Designation.ToLowerInvariant()}";
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if (spatialNodesById.TryGetValue(lagrangeId, out var lagrangeNode))
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{
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lagrangeNode.Position = lagrange.Position;
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}
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}
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for (var moonIndex = 0; moonIndex < planet.MoonCount; moonIndex += 1)
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{
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var moonId = $"node-{system.Definition.Id}-planet-{planetIndex + 1}-moon-{moonIndex + 1}";
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if (!spatialNodesById.TryGetValue(moonId, out var moonNode))
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{
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continue;
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}
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moonNode.Position = Add(planetPosition, ComputeMoonOffset(planet, moonIndex, worldTimeSeconds));
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}
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}
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}
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foreach (var station in world.Stations)
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{
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if (station.AnchorNodeId is null || !spatialNodesById.TryGetValue(station.AnchorNodeId, out var anchorNode))
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{
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continue;
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}
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station.Position = anchorNode.Position;
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if (station.NodeId is not null && spatialNodesById.TryGetValue(station.NodeId, out var stationNode))
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{
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stationNode.Position = station.Position;
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}
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}
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foreach (var node in world.Nodes)
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{
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if (node.AnchorNodeId is null || !spatialNodesById.TryGetValue(node.AnchorNodeId, out var anchorNode))
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{
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continue;
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}
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node.Position = Add(anchorNode.Position, ComputeResourceNodeOffset(node, worldTimeSeconds));
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if (spatialNodesById.TryGetValue(node.Id, out var resourceNode))
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{
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resourceNode.Position = node.Position;
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}
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}
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foreach (var ship in world.Ships.Where(ship => ship.DockedStationId is not null))
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{
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var station = world.Stations.FirstOrDefault(candidate => candidate.Id == ship.DockedStationId);
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if (station is null)
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{
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continue;
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}
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var dockedPosition = GetShipDockedPosition(ship, station);
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ship.Position = dockedPosition;
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ship.TargetPosition = dockedPosition;
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}
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}
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private static void SyncSpatialState(SimulationWorld world)
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{
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foreach (var bubble in world.LocalBubbles)
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{
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bubble.OccupantShipIds.Clear();
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}
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foreach (var ship in world.Ships)
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{
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ship.SpatialState.CurrentSystemId = ship.SystemId;
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ship.SpatialState.LocalPosition = ship.Position;
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ship.SpatialState.SystemPosition = ship.Position;
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if (ship.SpatialState.Transit is not null)
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{
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ship.SpatialState.CurrentNodeId = null;
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ship.SpatialState.CurrentBubbleId = null;
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continue;
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}
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ship.SpatialState.SpaceLayer = SpaceLayerKinds.LocalSpace;
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ship.SpatialState.MovementRegime = MovementRegimeKinds.LocalFlight;
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var nearestNode = world.SpatialNodes
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.Where(candidate => candidate.SystemId == ship.SystemId)
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.OrderBy(candidate => candidate.Position.DistanceTo(ship.Position))
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.FirstOrDefault();
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ship.SpatialState.CurrentNodeId = nearestNode?.Id;
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ship.SpatialState.CurrentBubbleId = nearestNode?.BubbleId;
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if (nearestNode is not null)
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{
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var nearestBubble = world.LocalBubbles.FirstOrDefault(candidate => candidate.Id == nearestNode.BubbleId);
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nearestBubble?.OccupantShipIds.Add(ship.Id);
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}
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if (ship.DockedStationId is null)
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{
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continue;
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}
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var station = world.Stations.FirstOrDefault(candidate => candidate.Id == ship.DockedStationId);
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if (station?.BubbleId is null)
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{
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continue;
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}
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ship.SpatialState.CurrentNodeId = station.NodeId;
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ship.SpatialState.CurrentBubbleId = station.BubbleId;
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var bubble = world.LocalBubbles.FirstOrDefault(candidate => candidate.Id == station.BubbleId);
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bubble?.OccupantShipIds.Add(ship.Id);
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}
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}
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private readonly record struct LagrangePointPlacement(string Designation, Vector3 Position);
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}
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