moved the particle system and the entity component system into their own nuget packages

2026-07-24 12:06:37 +00:00 · 2017-03-07 22:08:31 +10:00
parent 1b6df14681
commit c236e6dfd5
71 changed files with 422 additions and 83 deletions
@@ -0,0 +1,52 @@
+using System;
+using Microsoft.Xna.Framework;
+
+namespace MonoGame.Extended.Particles.Modifiers.Containers
+{
+    public class CircleContainerModifier : IModifier
+    {
+        public float Radius { get; set; }
+        public bool Inside { get; set; } = true;
+        public float RestitutionCoefficient { get; set; } = 1;
+
+        public unsafe void Update(float elapsedSeconds, ParticleBuffer.ParticleIterator iterator)
+        {
+            var radiusSq = Radius*Radius;
+            while (iterator.HasNext)
+            {
+                var particle = iterator.Next();
+                var localPos = particle->Position - particle->TriggerPos;
+
+                var distSq = localPos.LengthSquared();
+                var normal = localPos;
+                normal.Normalize();
+
+                if (Inside)
+                {
+                    if (distSq < radiusSq) continue;
+
+                    SetReflected(distSq, particle, normal);
+                }
+                else
+                {
+                    if (distSq > radiusSq) continue;
+
+                    SetReflected(distSq, particle, -normal);
+                }
+            }
+        }
+
+        private unsafe void SetReflected(float distSq, Particle* particle, Vector2 normal)
+        {
+            var dist = (float) Math.Sqrt(distSq);
+            var d = dist - Radius; // how far outside the circle is the particle
+
+            var twoRestDot = 2*RestitutionCoefficient*
+                             Vector2.Dot(particle->Velocity, normal);
+            particle->Velocity -= twoRestDot*normal;
+
+            // exact computation requires sqrt or goniometrics
+            particle->Position -= normal*d;
+        }
+    }
+}