117 lines
3.5 KiB
C#
117 lines
3.5 KiB
C#
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using System;
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using System.Collections.Generic;
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using FarseerPhysics.Dynamics;
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using Microsoft.Xna.Framework;
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namespace FarseerPhysics.Controllers
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{
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public enum GravityType
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{
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Linear,
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DistanceSquared
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}
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public class GravityController : Controller
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{
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public List<Body> Bodies = new List<Body>();
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public List<Vector2> Points = new List<Vector2>();
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public GravityController(float strength)
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: base(ControllerType.GravityController)
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{
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Strength = strength;
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MaxRadius = float.MaxValue;
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}
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public GravityController(float strength, float maxRadius, float minRadius)
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: base(ControllerType.GravityController)
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{
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MinRadius = minRadius;
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MaxRadius = maxRadius;
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Strength = strength;
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}
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public float MinRadius { get; set; }
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public float MaxRadius { get; set; }
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public float Strength { get; set; }
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public GravityType GravityType { get; set; }
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public override void Update(float dt)
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{
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Vector2 f = Vector2.Zero;
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foreach (Body body1 in World.BodyList)
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{
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if (!IsActiveOn(body1))
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continue;
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foreach (Body body2 in Bodies)
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{
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if (body1 == body2 || (body1.IsStatic && body2.IsStatic) || !body2.Enabled)
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continue;
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Vector2 d = body2.WorldCenter - body1.WorldCenter;
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float r2 = d.LengthSquared();
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if (r2 < Settings.Epsilon)
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continue;
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float r = d.Length();
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if (r >= MaxRadius || r <= MinRadius)
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continue;
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switch (GravityType)
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{
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case GravityType.DistanceSquared:
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f = Strength / r2 / (float)Math.Sqrt(r2) * body1.Mass * body2.Mass * d;
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break;
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case GravityType.Linear:
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f = Strength / r2 * body1.Mass * body2.Mass * d;
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break;
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}
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body1.ApplyForce(ref f);
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Vector2.Negate(ref f, out f);
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body2.ApplyForce(ref f);
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}
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foreach (Vector2 point in Points)
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{
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Vector2 d = point - body1.Position;
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float r2 = d.LengthSquared();
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if (r2 < Settings.Epsilon)
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continue;
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float r = d.Length();
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if (r >= MaxRadius || r <= MinRadius)
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continue;
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switch (GravityType)
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{
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case GravityType.DistanceSquared:
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f = Strength / r2 / (float)Math.Sqrt(r2) * body1.Mass * d;
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break;
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case GravityType.Linear:
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f = Strength / r2 * body1.Mass * d;
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break;
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}
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body1.ApplyForce(ref f);
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}
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}
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}
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public void AddBody(Body body)
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{
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Bodies.Add(body);
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}
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public void AddPoint(Vector2 point)
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{
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Points.Add(point);
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}
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}
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}
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