First commit

Subsurface/Particles/Particle.cs

@@ -0,0 +1,159 @@
+using FarseerPhysics;
+using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework.Graphics;
+
+namespace Subsurface.Particles
+{
+    class Particle
+    {
+        private ParticlePrefab prefab;
+
+        private Vector2 position;
+        private Vector2 prevPosition;
+
+        private Vector2 velocity;
+
+        private float rotation;
+        private float prevRotation;
+
+        private float angularVelocity;
+
+        private Vector2 size;
+        private Vector2 sizeChange;
+
+        private Color color;
+        private float alpha;
+
+        private float lifeTime;
+
+        private Vector2 velocityChange;
+
+        private Vector2 drawPosition;
+
+        private float checkCollisionTimer;
+
+        public bool InWater
+        {
+            get { return prefab.inWater; }        
+        }
+
+        public Vector2 Size
+        {
+            get { return size; }
+            set { size = value; }
+        }
+
+        public Vector2 VelocityChange
+        {
+            get { return velocityChange; }
+            set { velocityChange = value; }
+        }
+        
+        public void Init(Vector2 position, float rotation, Vector2 speed, ParticlePrefab prefab)
+        {
+            this.prefab = prefab;
+
+            this.position = position;
+            prevPosition = position;
+
+            drawPosition = ConvertUnits.ToDisplayUnits(position);
+
+            velocity = speed;
+
+            this.rotation = rotation + ToolBox.RandomFloat(prefab.startRotationMin, prefab.startRotationMax);    
+            prevRotation = rotation;
+
+            float rand = (float)Game1.localRandom.NextDouble();
+            angularVelocity = prefab.angularVelocityMin + (prefab.angularVelocityMax - prefab.angularVelocityMin) * rand;
+
+            lifeTime = prefab.lifeTime;
+
+            rand = (float)Game1.localRandom.NextDouble();
+            size = prefab.startSizeMin + (prefab.startSizeMax - prefab.startSizeMin)*rand;
+
+            rand = (float)Game1.localRandom.NextDouble();
+            sizeChange = prefab.sizeChangeMin + (prefab.sizeChangeMax - prefab.sizeChangeMin) * rand;
+                               
+
+            color = prefab.startColor;
+            alpha = prefab.startAlpha;
+            
+            velocityChange = prefab.velocityChange;
+            
+        }
+
+        public bool Update(float deltaTime)
+        {
+            //over 3 times faster than position += velocity * deltatime
+            position.X += velocity.X * deltaTime;
+            position.Y += velocity.Y * deltaTime;
+
+            if (prefab.rotateToDirection)
+            {
+                rotation = ToolBox.VectorToAngle(velocity);
+            }
+            else
+            {
+                rotation += angularVelocity * deltaTime;
+            }
+
+            velocity.X += velocityChange.X * deltaTime;
+            velocity.Y += velocityChange.Y * deltaTime; 
+
+            size.X += sizeChange.X * deltaTime;
+            size.Y += sizeChange.Y * deltaTime;
+
+            alpha += prefab.colorChange.W * deltaTime;
+
+            color = new Color(
+                color.R / 255.0f + prefab.colorChange.X * deltaTime,
+                color.G / 255.0f + prefab.colorChange.Y * deltaTime,
+                color.B / 255.0f + prefab.colorChange.Z * deltaTime);
+
+            if (prefab.deleteOnHit)
+            {
+                if (checkCollisionTimer > 0.0f)
+                {
+                    checkCollisionTimer -= deltaTime;
+                }
+                else
+                {
+                    if (Map.InsideWall(new Vector2(drawPosition.X, -drawPosition.Y)))
+                    {
+                        return false;
+                    }
+                    checkCollisionTimer = 0.05f;
+                }
+            }
+
+            lifeTime -= deltaTime;
+
+            if (lifeTime <= 0.0f || alpha <= 0.0f || size.X <= 0.0f || size.Y <= 0.0f) return false;
+
+            return true;
+        }
+        
+        public void Draw(SpriteBatch spriteBatch)
+        {
+            drawPosition = Physics.Interpolate(prevPosition, position);
+            drawPosition.Y = -drawPosition.Y;
+            float drawRotation = Physics.Interpolate(prevRotation, rotation);
+
+            drawPosition = ConvertUnits.ToDisplayUnits(drawPosition);
+
+
+            spriteBatch.Draw(
+                prefab.sprite.Texture, 
+                drawPosition, 
+                null, 
+                color*alpha, 
+                drawRotation, 
+                prefab.sprite.origin, 
+                size,
+                SpriteEffects.None, prefab.sprite.Depth);
+
+            prevPosition = position;
+            prevRotation = rotation;
+        }
+    }
+}