Trail experiment

annotations/src/main/resources/classids.properties

@@ -11,6 +11,7 @@ mindustry.entities.def.PuddleComp=7
 mindustry.entities.def.TileComp=8
 mindustry.type.Weather.WeatherComp=9
 phantom=10
+reaper=14
 titan=13
 vanguard=11
 wraith=12

annotations/src/main/resources/revisions/TrailUnitEntity/0.json

@@ -0,0 +1 @@
+{fields:[{name:elevation,type:float,size:4},{name:health,type:float,size:4},{name:rotation,type:float,size:4},{name:shield,type:float,size:4},{name:team,type:mindustry.game.Team,size:-1},{name:type,type:mindustry.type.UnitType,size:-1},{name:x,type:float,size:4},{name:y,type:float,size:4}]}

core/src/mindustry/async/PhysicsProcess.java

@@ -49,9 +49,8 @@ public class PhysicsProcess implements AsyncProcess{
                 //add bodies to entities that have none
                 FixtureDef fd = new FixtureDef();
                 fd.shape = new CircleShape(entity.hitSize() / 2f);
-                //TODO does this scale well?
-                fd.density = 5f; //5.0f * entity.mass();
-                fd.restitution = 0.05f;
+                fd.density = 5f;
+                fd.restitution = 0.0f;
                 fd.filter.maskBits = fd.filter.categoryBits = (grounded ? ground : flying).maskBits;
 
                 def.position.set(entity);
@@ -93,6 +92,8 @@ public class PhysicsProcess implements AsyncProcess{
 
             //write velocity
             ref.body.setLinearVelocity(ref.velocity);
+
+            ref.lastVelocity.set(ref.velocity);
         }
 
         physics.step(Core.graphics.getDeltaTime(), 8, 8);
@@ -101,6 +102,8 @@ public class PhysicsProcess implements AsyncProcess{
         for(PhysicRef ref : refs){
             //get delta vector
             ref.delta.set(ref.body.getPosition()).sub(ref.lastPosition);
+
+            ref.velocity.set(ref.body.getLinearVelocity());
         }
     }
 
@@ -116,6 +119,8 @@ public class PhysicsProcess implements AsyncProcess{
 
             //save last position
             ref.position.set(entity);
+
+            entity.vel().add(ref.velocity).sub(ref.lastVelocity);
         }
     }
 
@@ -139,7 +144,7 @@ public class PhysicsProcess implements AsyncProcess{
         Physicsc entity;
         Body body;
         boolean wasGround = true;
-        Vec2 lastPosition = new Vec2(), delta = new Vec2(), velocity = new Vec2(), position = new Vec2();
+        Vec2 lastPosition = new Vec2(), delta = new Vec2(), velocity = new Vec2(), lastVelocity = new Vec2(), position = new Vec2();
 
         public PhysicRef(Physicsc entity, Body body){
             this.entity = entity;

core/src/mindustry/content/UnitTypes.java

@@ -17,7 +17,7 @@ public class UnitTypes implements ContentList{
     public static @EntityDef({Unitc.class, Legsc.class}) UnitType dagger;
     public static @EntityDef({Unitc.class, WaterMovec.class}) UnitType vanguard;
     public static @EntityDef({Unitc.class, Minerc.class}) UnitType draug;
-    public static @EntityDef({Unitc.class}) UnitType wraith;
+    public static @EntityDef({Unitc.class, Trailc.class}) UnitType wraith;
     public static @EntityDef({Unitc.class}) UnitType reaper;
     public static @EntityDef({Unitc.class}) UnitType spirit;
     public static @EntityDef({Unitc.class, Builderc.class}) UnitType phantom;
@@ -86,9 +86,9 @@ public class UnitTypes implements ContentList{
         }};
 
         reaper = new UnitType("reaper"){{
-            speed = 1f;
+            speed = 1.1f;
             accel = 0.08f;
-            drag = 0f;
+            drag = 0.05f;
             mass = 30f;
             flying = true;
             health = 75000;

core/src/mindustry/entities/def/TrailComp.java

@@ -0,0 +1,9 @@
+package mindustry.entities.def;
+
+import mindustry.annotations.Annotations.*;
+import mindustry.graphics.*;
+
+@Component
+abstract class TrailComp{
+    transient Trail trail = new Trail();
+}

core/src/mindustry/graphics/Trail.java

@@ -0,0 +1,43 @@
+package mindustry.graphics;
+
+import arc.graphics.*;
+import arc.graphics.g2d.*;
+import arc.math.*;
+import arc.math.geom.*;
+import arc.struct.*;
+import arc.util.pooling.*;
+
+public class Trail{
+    private static final int length = 20;
+    private Array<Vec3> points = new Array<>();
+    private float lastX = -1, lastY = -1;
+
+    public void draw(Color color, float width){
+        Draw.color(color);
+
+        for(int i = 0; i < points.size - 1; i++){
+            Vec3 c = points.get(i);
+            Vec3 n = points.get(i + 1);
+            float size = width * 1f / length;
+
+            float cx = Mathf.sin(c.z) * i * size, cy = Mathf.cos(c.z) * i * size, nx = Mathf.sin(n.z) * (i + 1) * size, ny = Mathf.cos(n.z) * (i + 1) * size;
+            Fill.quad(c.x - cx, c.y - cy, c.x + cx, c.y + cy, n.x + nx, n.y + ny, n.x - nx, n.y - ny);
+        }
+
+        Draw.reset();
+    }
+
+    public void update(float x, float y){
+        if(points.size > length){
+            Pools.free(points.first());
+            points.remove(0);
+        }
+
+        float angle = -Angles.angle(x, y, lastX, lastY);
+
+        points.add(Pools.obtain(Vec3.class, Vec3::new).set(x, y, (angle) * Mathf.degRad));
+
+        lastX = x;
+        lastY = y;
+    }
+}

core/src/mindustry/input/DesktopInput.java

@@ -542,7 +542,11 @@ public class DesktopInput extends InputHandler{
             unit.lookAt(mouseAngle);
         }else{
             if(!unit.vel().isZero(0.01f)){
-                unit.lookAt(unit.vel().angle());
+                if(unit.type().flying){
+                    unit.rotation(unit.vel().angle());
+                }else{
+                    unit.lookAt(unit.vel().angle());
+                }
             }
         }
 

core/src/mindustry/type/UnitType.java

@@ -189,6 +189,15 @@ public class UnitType extends UnlockableContent{
     public void drawEngine(Unitc unit){
         if(!unit.isFlying()) return;
 
+        if(unit instanceof Trailc){
+            Trail trail = ((Trailc)unit).trail();
+
+            float cx = unit.x() + Angles.trnsx(unit.rotation() + 180, engineOffset),
+            cy = unit.y() + Angles.trnsy(unit.rotation() + 180, engineOffset);
+            trail.update(cx, cy);
+            trail.draw(unit.team().color, (engineSize + Mathf.absin(Time.time(), 2f, engineSize / 4f) * unit.elevation()));
+        }
+
         Draw.color(unit.team().color);
         Fill.circle(
             unit.x() + Angles.trnsx(unit.rotation() + 180, engineOffset),