Particle system improvements:

- particles can collide with the outer walls of the sub
- drag + waterdrag parameters
- fixed particles "twitching" when the submarine is moving fast
- submarine velocity only affects the initial velocity of the particles (i.e. accelerating the sub doesn't automatically accelerate them)

Subsurface/Barotrauma.csproj

@@ -817,6 +817,9 @@
     <Content Include="Content\Particles\flames.png">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
+    <Content Include="Content\Particles\shrapnel.png">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </Content>
     <Content Include="Content\UI\damageOverlay.png">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>

Subsurface/Content/Particles/ParticlePrefabs.xml

@@ -234,4 +234,68 @@
     velocitychange="0.0, 1.0">
     <sprite texture="Content/Particles/spatter.png" sourcerect="128,128,128,128"/>
   </flare>
+  
+  <shrapnel
+    startsizemin="0.1,0.1" startsizemax="1.0,1.0"
+    startrotationmin ="0.0" startrotationmax="360"
+    startcolor="1.0, 1.0, 1.0" startalpha="1.0"
+    colorchange="0.0, 0.0, 0.0, -0.3"
+    lifetime="10.0"
+    drawtarget="both"    
+    collideswithwalls="true"
+    collisionradius="10.0"    
+    restitution="0.2"
+    waterdrag="0.1"
+    growtime ="0.0"
+    velocitychange="0.0, -5.0">
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="0,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="32,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="64,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="96,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="128,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="160,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="192,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="224,0,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="0,32,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="32,32,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="64,32,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="96,32,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="128,32,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="160,32,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="192,32,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="224,32,32,32"/>
+  </shrapnel>
+  
+  <iceshards
+    startsizemin="0.1,0.1" startsizemax="1.0,1.0"
+    startrotationmin ="0.0" startrotationmax="360"
+    startcolor="1.0, 1.0, 1.0" startalpha="1.0"
+    colorchange="0.0, 0.0, 0.0, -0.3"
+    lifetime="10.0"
+    drawtarget="both"
+    collideswithwalls="true"
+    collisionradius="10.0"
+    restitution="0.2"
+    waterdrag="0.3"
+    growtime ="0.0"
+    velocitychange="0.0, -5.0">
+    
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="0,64,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="32,64,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="64,64,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="96,64,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="128,64,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="160,64,48,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="208,64,48,32"/>
+    
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="0,96,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="32,96,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="64,96,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="96,96,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="128,96,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="160,96,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="192,96,32,32"/>
+    <sprite texture="Content/Particles/shrapnel.png" sourcerect="224,96,32,32"/>
+  </iceshards>  
+  
 </prefabs>

Subsurface/Source/Map/Gap.cs

@@ -163,6 +163,8 @@ namespace Barotrauma
                 hulls[1] = temp;
             }
 
+            flowTargetHull = hulls[0];
+
             for (int i = 0 ; i <2; i++)
             {
                 if (hulls[i]==null) continue;

Subsurface/Source/Map/Structure.cs

@@ -537,8 +537,22 @@ namespace Barotrauma
 
             if (sectionIndex < 0 || sectionIndex > sections.Length - 1) return;
 
-            if (GameMain.Client == null) SetDamage(sectionIndex, sections[sectionIndex].damage + damage);
+            var section = sections[sectionIndex];
 
+            int particleAmount = (int)(Math.Min(Health - section.damage, damage) * Rand.Range(0.1f, 1.0f));
+            for (int i = 0; i < particleAmount; i++)
+            {
+                Vector2 particlePos = new Vector2(
+                    Rand.Range(section.rect.X, section.rect.Right),
+                    Rand.Range(section.rect.Y - section.rect.Height, section.rect.Y));
+
+                if (Submarine != null) particlePos += Submarine.DrawPosition;
+
+                var particle = GameMain.ParticleManager.CreateParticle("shrapnel", particlePos, Rand.Vector(Rand.Range(1.0f, 50.0f)));
+                if (particle == null) break;
+            }
+
+            if (GameMain.Client == null) SetDamage(sectionIndex, section.damage + damage);
         }
 
         public int FindSectionIndex(Vector2 displayPos)

Subsurface/Source/Map/SubmarineBody.cs

@@ -445,6 +445,18 @@ namespace Barotrauma
 
                 ApplyImpact(wallImpact, -collisionNormal, contact);
 
+                Vector2 n;
+                FixedArray2<Vector2> particlePos;
+                contact.GetWorldManifold(out n, out particlePos);
+                
+                int particleAmount = (int)(wallImpact*10.0f);
+                for (int i = 0; i < particleAmount; i++)
+                {
+                    var particle = GameMain.ParticleManager.CreateParticle("iceshards",
+                        ConvertUnits.ToDisplayUnits(particlePos[0]) + Rand.Vector(Rand.Range(1.0f, 50.0f)), 
+                        Rand.Vector(Rand.Range(50.0f,500.0f)) + Velocity);
+                }
+            
                 return true;
             }
 

Subsurface/Source/Particles/Particle.cs

@@ -37,6 +37,7 @@ namespace Barotrauma.Particles
         private Vector2 velocityChange;
 
         private Vector2 drawPosition;
+        private float drawRotation;
 
         //private float checkCollisionTimer;
 
@@ -66,6 +67,12 @@ namespace Barotrauma.Particles
             set { velocityChange = value; }
         }
 
+        public Vector2 Velocity
+        {
+            get { return velocity; }
+            set { velocity = value; }
+        }
+        
         public void Init(ParticlePrefab prefab, Vector2 position, Vector2 speed, float rotation, Hull hullGuess = null)
         {
 
@@ -74,26 +81,19 @@ namespace Barotrauma.Particles
             spriteIndex = Rand.Int(prefab.Sprites.Count);
 
             currentHull = Hull.FindHull(position, hullGuess);
-            //if (currentHull != null && currentHull.Submarine != null)
-            //{
-            //    Vector2 subVel = ConvertUnits.ToDisplayUnits(currentHull.Submarine.Velocity);
-            //    //subVel.Y = -subVel.Y;
-            //    speed += subVel;
-            //}
-            //else
-            //{
-            //    int a = 1;
-            //}
-            //if (currentHull == null) position = Submarine.Loaded == null ? position : position + Submarine.Loaded.Position;
 
             this.position = position;
             prevPosition = position;
             
             drawPosition = position;
             
-            
             velocity = MathUtils.IsValid(speed) ? speed : Vector2.Zero;
 
+            if (currentHull != null && currentHull.Submarine != null)
+            {
+                velocity += ConvertUnits.ToDisplayUnits(currentHull.Submarine.Velocity);
+            }
+
             this.rotation = rotation + Rand.Range(prefab.StartRotationMin, prefab.StartRotationMax);    
             prevRotation = rotation;
 
@@ -142,12 +142,12 @@ namespace Barotrauma.Particles
 
         public bool Update(float deltaTime)
         {
-
+            prevPosition = position;
-            Vector2 subVel = currentHull ==null || currentHull.Submarine==null ? Vector2.Zero : ConvertUnits.ToDisplayUnits(currentHull.Submarine.Velocity);
+            prevRotation = rotation;
 
             //over 3 times faster than position += velocity * deltatime
-            position.X += (velocity.X+subVel.X) * deltaTime;
+            position.X += velocity.X * deltaTime;
-            position.Y += (velocity.Y+subVel.Y) * deltaTime;
+            position.Y += velocity.Y * deltaTime;
 
             if (prefab.RotateToDirection)
             {
@@ -161,6 +161,16 @@ namespace Barotrauma.Particles
                 rotation += angularVelocity * deltaTime;
             }
 
+            if (prefab.WaterDrag > 0.0f && 
+                (currentHull == null || (currentHull.Submarine != null && position.Y - currentHull.Submarine.DrawPosition.Y < currentHull.Surface)))
+            {
+                ApplyDrag(prefab.WaterDrag, deltaTime);
+            }
+            else if (prefab.Drag > 0.0f)
+            {
+                ApplyDrag(prefab.Drag, deltaTime);
+            }
+
             velocity.X += velocityChange.X * deltaTime;
             velocity.Y += velocityChange.Y * deltaTime; 
 
@@ -174,11 +184,20 @@ namespace Barotrauma.Particles
                 color.G / 255.0f + prefab.ColorChange.Y * deltaTime,
                 color.B / 255.0f + prefab.ColorChange.Z * deltaTime);
             
-            if ((prefab.DeleteOnCollision || prefab.CollidesWithWalls) && currentHull!=null)
+            if (prefab.DeleteOnCollision || prefab.CollidesWithWalls)
             {
                 Vector2 edgePos =  position + prefab.CollisionRadius * Vector2.Normalize(velocity) * size.X;
 
-                if (!Submarine.RectContains(currentHull.WorldRect, edgePos))
+                if (currentHull == null)
+                {
+                    var collidedHull = Hull.FindHullOld(edgePos);
+                    if (collidedHull != null)
+                    {
+                        if (prefab.DeleteOnCollision) return false;
+                        OnWallCollisionOutside(collidedHull);
+                    }
+                }
+                else if (!Submarine.RectContains(currentHull.WorldRect, edgePos))
                 {
                     if (prefab.DeleteOnCollision) return false;
 
@@ -196,15 +215,13 @@ namespace Barotrauma.Particles
                             if (Math.Sign(velocity.X) != Math.Sign(gap.WorldRect.Center.X - currentHull.WorldRect.Center.X)) continue;
                         }
 
-                        //Rectangle enlargedRect = new Rectangle(gap.Rect.X - 10, gap.Rect.Y + 10, gap.Rect.Width + 20, gap.Rect.Height + 20);
-                        //if (!Submarine.RectContains(enlargedRect, position)) continue;
                         gapFound = true;
                     }
 
                     if (!gapFound)
                     {
 
-                        OnWallCollision(currentHull, edgePos);
+                        OnWallCollisionInside(currentHull, edgePos);
                     }
                     else
                     {
@@ -212,21 +229,9 @@ namespace Barotrauma.Particles
                         hullGaps = currentHull == null ? new List<Gap>() : currentHull.ConnectedGaps;
 
                         if (OnChangeHull != null) OnChangeHull(edgePos, currentHull);
-
                     }                    
-
-                    //Hull prevHull = Hull.FindHull(prevPosition, hullLimits, currentHull);
-
-                    //if (prevHull == null) return false;
-
                 }
               
-                //if (position.Y < currentHull.Rect.Y-currentHull.Rect.Height)
-                //{
-                //    position.Y = currentHull.Rect.Y - currentHull.Rect.Height;
-                //    velocity.Y *= -0.2f;
-                //}
-                //if (!Submarine.RectContains(currentHull.Rect, position)) return false;
             }
 
             lifeTime -= deltaTime;
@@ -236,10 +241,22 @@ namespace Barotrauma.Particles
             return true;
         }
 
-        private void OnWallCollision(Hull prevHull, Vector2 position)
+        private void ApplyDrag(float dragCoefficient, float deltaTime)
+        {
+            if (velocity == Vector2.Zero) return;
+
+            float speed = velocity.Length();
+            velocity -= (velocity / speed) * Math.Min(speed * speed * prefab.WaterDrag * deltaTime, 1.0f);
+        }
+
+        private void OnWallCollisionInside(Hull prevHull, Vector2 position)
         {
             Rectangle prevHullRect = prevHull.WorldRect;
 
+            Vector2 subVel = ConvertUnits.ToDisplayUnits(prevHull.Submarine.Velocity);
+
+            velocity -= subVel;
+
             if (position.Y < prevHullRect.Y - prevHullRect.Height)
             {
                 position.Y = prevHullRect.Y - prevHullRect.Height + 1.0f;
@@ -264,30 +281,64 @@ namespace Barotrauma.Particles
             }
 
             velocity *= prefab.Restitution;
+
+            velocity += subVel;
+        }
+
+
+        private void OnWallCollisionOutside(Hull collisionHull)
+        {
+            Rectangle hullRect = collisionHull.WorldRect;
+            
+            if (position.Y < hullRect.Y - hullRect.Height)
+            {
+                position.Y = hullRect.Y - hullRect.Height - 1.0f;
+                velocity.Y = -velocity.Y;
+            }
+            else if (position.Y > hullRect.Y)
+            {
+                position.Y = hullRect.Y + 1.0f;
+                velocity.X = Math.Abs(velocity.Y) * Math.Sign(velocity.X);
+                velocity.Y = -velocity.Y;
+            }
+
+            if (position.X < hullRect.X)
+            {
+                position.X = hullRect.X - 1.0f;
+                velocity.X = -velocity.X;
+            }
+            else if (position.X > hullRect.X + hullRect.Width)
+            {
+                position.X = hullRect.X + hullRect.Width + 1.0f;
+                velocity.X = -velocity.X;
+            }
+
+            velocity *= prefab.Restitution;
+        }
+
+        public void UpdateDrawPos()
+        {
+            drawPosition = Physics.Interpolate(prevPosition, position);
+            drawRotation = Physics.Interpolate(prevRotation, rotation);
+
+            prevPosition = position;
+            prevRotation = rotation;
         }
         
         public void Draw(SpriteBatch spriteBatch)
         {
-            drawPosition = Physics.Interpolate(prevPosition, position);
-            float drawRotation = Physics.Interpolate(prevRotation, rotation);
-
-            //drawPosition = ConvertUnits.ToDisplayUnits(drawPosition);
-
             Vector2 drawSize = size;
 
-            if (prefab.GrowTime>0.0f && totalLifeTime-lifeTime < prefab.GrowTime)
+            if (prefab.GrowTime > 0.0f && totalLifeTime - lifeTime < prefab.GrowTime)
             {
                 drawSize *= ((totalLifeTime - lifeTime) / prefab.GrowTime);
             }
 
             prefab.Sprites[spriteIndex].Draw(spriteBatch,
-                new Vector2(drawPosition.X,  -drawPosition.Y), 
+                new Vector2(drawPosition.X, -drawPosition.Y),
                 color * alpha,
                 prefab.Sprites[spriteIndex].Origin, drawRotation,
                 drawSize, SpriteEffects.None, prefab.Sprites[spriteIndex].Depth);
-
-            prevPosition = position;
-            prevRotation = rotation;
         }
     }
 }

Subsurface/Source/Particles/ParticleManager.cs

@@ -113,6 +113,14 @@ namespace Barotrauma.Particles
             }
         }
 
+        public void UpdateTransforms()
+        {
+            for (int i = 0; i < particleCount; i++)
+            {
+                particles[i].UpdateDrawPos();
+            }
+        }
+
         public void Draw(SpriteBatch spriteBatch, bool inWater, ParticleBlendState blendState)
         {
             ParticlePrefab.DrawTargetType drawTarget = inWater ? ParticlePrefab.DrawTargetType.Water : ParticlePrefab.DrawTargetType.Air;

Subsurface/Source/Particles/ParticlePrefab.cs

@@ -20,6 +20,8 @@ namespace Barotrauma.Particles
         public readonly Vector2 StartSizeMin, StartSizeMax;
         public readonly Vector2 SizeChangeMin, SizeChangeMax;
 
+        public readonly float Drag, WaterDrag;
+
         public readonly Color StartColor;
         public readonly float StartAlpha;
 
@@ -89,6 +91,9 @@ namespace Barotrauma.Particles
                 SizeChangeMax = SizeChangeMin;
             }
 
+            Drag = ToolBox.GetAttributeFloat(element, "drag", 0.0f);
+            WaterDrag = ToolBox.GetAttributeFloat(element, "waterdrag", 0.0f);
+            
             Restitution = ToolBox.GetAttributeFloat(element, "restitution", 0.5f);
 
             switch (ToolBox.GetAttributeString(element, "blendstate", "alphablend"))

Subsurface/Source/Screens/GameScreen.cs

@@ -109,23 +109,24 @@ namespace Barotrauma
             }
 #endif
 
-            if (GameMain.GameSession!=null) GameMain.GameSession.Update((float)deltaTime);
-            //EventManager.Update(gameTime);
-
-            if (Level.Loaded != null) Level.Loaded.Update((float)deltaTime);
-
-            Character.UpdateAll(cam, (float)deltaTime);
-
-            BackgroundCreatureManager.Update(cam, (float)deltaTime);
-
-            GameMain.ParticleManager.Update((float)deltaTime);
-
-            StatusEffect.UpdateAll((float)deltaTime);
-
             Physics.accumulator = Math.Min(Physics.accumulator, Physics.step * 6);
             //Physics.accumulator = Physics.step;
             while (Physics.accumulator >= Physics.step)
             {
+
+                if (GameMain.GameSession != null) GameMain.GameSession.Update((float)Physics.step);
+                //EventManager.Update(gameTime);
+
+                if (Level.Loaded != null) Level.Loaded.Update((float)Physics.step);
+
+                Character.UpdateAll(cam, (float)Physics.step);
+
+                BackgroundCreatureManager.Update(cam, (float)Physics.step);
+
+                GameMain.ParticleManager.Update((float)Physics.step);
+
+                StatusEffect.UpdateAll((float)Physics.step);
+
                 if (Character.Controlled != null && Lights.LightManager.ViewTarget != null)
                 {
                     cam.TargetPos = Lights.LightManager.ViewTarget.WorldPosition;
@@ -210,6 +211,8 @@ namespace Barotrauma
                 sub.UpdateTransform();
             }
 
+            GameMain.ParticleManager.UpdateTransforms();
+
             GameMain.LightManager.ObstructVision = Character.Controlled != null && Character.Controlled.ObstructVision;
 
             GameMain.LightManager.UpdateLightMap(graphics, spriteBatch, cam);