celesteia archive, last updated april 9th 2024

Signed-off-by: hazel <hazel@hazelthats.me>

1 files changed, 42 insertions, 0 deletions

diff --git a/source/game/systems/physics/PhysicsSystem.cs b/source/game/systems/physics/PhysicsSystem.cs
new file mode 100644
index 0000000..3963cc1
--- /dev/null
+++ b/source/game/systems/physics/PhysicsSystem.cs
@@ -0,0 +1,42 @@
+using Celesteia.Game.Components;
+using Celesteia.Game.Components.Physics;
+using Microsoft.Xna.Framework;
+using MonoGame.Extended;
+using MonoGame.Extended.Entities;
+using MonoGame.Extended.Entities.Systems;
+
+namespace Celesteia.Game.Systems.Physics {
+    public class PhysicsSystem : EntityUpdateSystem {
+        public const float GRAVITY_CONSTANT = 9.7f;
+
+        public PhysicsSystem() : base(Aspect.All(typeof(PhysicsEntity), typeof(TargetPosition))) {}
+
+        private ComponentMapper<TargetPosition> targetPositionMapper;
+        private ComponentMapper<PhysicsEntity> physicsEntityMapper;
+
+        public override void Initialize(IComponentMapperService mapperService)
+        {
+            targetPositionMapper = mapperService.GetMapper<TargetPosition>();
+            physicsEntityMapper = mapperService.GetMapper<PhysicsEntity>();
+        }
+
+        public override void Update(GameTime gameTime)
+        {
+            foreach (int entityId in ActiveEntities) {
+                TargetPosition targetPosition = targetPositionMapper.Get(entityId);
+                PhysicsEntity physicsEntity = physicsEntityMapper.Get(entityId);
+
+                // Apply gravity if applicable
+                if (physicsEntity.Gravity) {
+                    if (physicsEntity.CollidingDown && physicsEntity.Velocity.Y > 0f) {
+                        physicsEntity.SetVelocity(physicsEntity.Velocity.X, 0.1f);
+                    }
+                    
+                    physicsEntity.AddVelocity(0f, physicsEntity.Mass * PhysicsSystem.GRAVITY_CONSTANT * gameTime.GetElapsedSeconds());
+                }
+
+                targetPosition.Target += physicsEntity.Velocity * gameTime.GetElapsedSeconds();
+            }
+        }
+    }
+}
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