Better physics system

build.gradle

@@ -200,7 +200,6 @@ project(":desktop"){
 
     dependencies{
         implementation project(":core")
-        implementation arcModule("natives:natives-box2d-desktop")
         implementation arcModule("natives:natives-desktop")
         implementation arcModule("natives:natives-freetype-desktop")
         implementation 'com.github.MinnDevelopment:java-discord-rpc:v2.0.1'
@@ -239,7 +238,6 @@ project(":ios"){
 
         implementation arcModule("natives:natives-ios")
         implementation arcModule("natives:natives-freetype-ios")
-        implementation arcModule("natives:natives-box2d-ios")
         implementation arcModule("backends:backend-robovm")
 
         compileOnly project(":annotations")
@@ -282,7 +280,6 @@ project(":core"){
         api "org.lz4:lz4-java:1.4.1"
         api arcModule("arc-core")
         api arcModule("extensions:freetype")
-        api arcModule("extensions:box2d")
         api arcModule("extensions:g3d")
         api arcModule("extensions:fx")
         api arcModule("extensions:arcnet")
@@ -299,7 +296,6 @@ project(":server"){
 
     dependencies{
         implementation project(":core")
-        implementation arcModule("natives:natives-box2d-desktop")
         implementation arcModule("backends:backend-headless")
     }
 }
@@ -312,7 +308,6 @@ project(":tests"){
         testImplementation "org.junit.jupiter:junit-jupiter-params:5.3.1"
         testImplementation "org.junit.jupiter:junit-jupiter-api:5.3.1"
         testImplementation arcModule("backends:backend-headless")
-        testImplementation arcModule("natives:natives-box2d-desktop")
         testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine:5.3.1"
     }
 
@@ -334,7 +329,6 @@ project(":tools"){
 
         implementation arcModule("natives:natives-desktop")
         implementation arcModule("natives:natives-freetype-desktop")
-        implementation arcModule("natives:natives-box2d-desktop")
         implementation arcModule("backends:backend-headless")
     }
 }

core/src/mindustry/ai/types/FormationAI.java

@@ -73,7 +73,7 @@ public class FormationAI extends AIController implements FormationMember{
             //TODO return formation size
             //eturn ((Commanderc)unit).formation().
         }
-        return unit.hitSize * 1f;
+        return unit.hitSize * 0.65f;
     }
 
     @Override

core/src/mindustry/async/PhysicsProcess.java

@@ -1,31 +1,19 @@
 package mindustry.async;
 
-import arc.box2d.*;
+import arc.math.*;
-import arc.box2d.BodyDef.*;
 import arc.math.geom.*;
+import arc.math.geom.QuadTree.*;
 import arc.struct.*;
+import mindustry.*;
 import mindustry.entities.*;
+import mindustry.async.PhysicsProcess.PhysicsWorld.*;
 import mindustry.gen.*;
 
 public class PhysicsProcess implements AsyncProcess{
-    private Physics physics;
+    private PhysicsWorld physics;
     private Seq<PhysicRef> refs = new Seq<>(false);
-    private BodyDef def;
+    //currently only enabled for units
-
+    private EntityGroup<? extends Physicsc> group = Groups.unit;
-    private EntityGroup<? extends Physicsc> group;
-    private Filter flying = new Filter(){{
-        maskBits = categoryBits = 2;
-    }}, ground = new Filter(){{
-        maskBits = categoryBits = 1;
-    }};
-
-    public PhysicsProcess(){
-        def = new BodyDef();
-        def.type = BodyType.dynamicBody;
-
-        //currently only enabled for units
-        group = Groups.unit;
-    }
 
     @Override
     public void begin(){
@@ -34,7 +22,7 @@ public class PhysicsProcess implements AsyncProcess{
         //remove stale entities
         refs.removeAll(ref -> {
             if(!ref.entity.isAdded()){
-                physics.destroyBody(ref.body);
+                physics.remove(ref.body);
                 ref.entity.physref(null);
                 return true;
             }
@@ -44,37 +32,29 @@ public class PhysicsProcess implements AsyncProcess{
         //find entities without bodies and assign them
         for(Physicsc entity : group){
             boolean grounded = entity.isGrounded();
-            int bits = grounded ? ground.maskBits : flying.maskBits;
 
             if(entity.physref() == null){
-                //add bodies to entities that have none
+                PhysicsBody body = new PhysicsBody();
-                FixtureDef fd = new FixtureDef();
+                body.x = entity.x();
-                fd.shape = new CircleShape(entity.hitSize() / 2f);
+                body.y = entity.y();
-                fd.density = 5f;
+                body.mass = entity.mass();
-                fd.restitution = 0.0f;
+                body.radius = entity.hitSize() / 2f;
-                fd.filter.maskBits = fd.filter.categoryBits = (grounded ? ground : flying).maskBits;
+                body.flag = grounded ? 1 : 0;
-
-                def.position.set(entity);
-
-                Body body = physics.createBody(def);
-                body.createFixture(fd);
 
                 PhysicRef ref = new PhysicRef(entity, body);
                 refs.add(ref);
 
                 entity.physref(ref);
+
+                physics.add(body);
             }
 
             //save last position
             PhysicRef ref = entity.physref();
 
-            if(ref.body.getFixtureList().any() && ref.body.getFixtureList().first().getFilterData().categoryBits != bits){
+            ref.body.flag = grounded ? 1 : 0;
-                //set correct filter
+            ref.x = entity.x();
-                ref.body.getFixtureList().first().setFilterData(grounded ? ground : flying);
+            ref.y = entity.y();
-            }
-
-            ref.velocity.set(entity.deltaX(), entity.deltaY());
-            ref.position.set(entity);
         }
     }
 
@@ -85,26 +65,11 @@ public class PhysicsProcess implements AsyncProcess{
         //get last position vectors before step
         for(PhysicRef ref : refs){
             //force set target position
-            ref.body.setPosition(ref.position.x, ref.position.y);
+            ref.body.x = ref.x;
-
+            ref.body.y = ref.y;
-            //save last position for delta
-            ref.lastPosition.set(ref.body.getPosition());
-
-            //write velocity
-            ref.body.setLinearVelocity(ref.velocity);
-
-            ref.lastVelocity.set(ref.velocity);
         }
 
-        physics.step(1f/45f, 5, 8);
+        physics.update();
-
-        //get delta vectors
-        for(PhysicRef ref : refs){
-            //get delta vector
-            ref.delta.set(ref.body.getPosition()).sub(ref.lastPosition);
-
-            ref.velocity.set(ref.body.getLinearVelocity());
-        }
     }
 
     @Override
@@ -115,13 +80,8 @@ public class PhysicsProcess implements AsyncProcess{
         for(PhysicRef ref : refs){
             Physicsc entity = ref.entity;
 
-            entity.move(ref.delta.x, ref.delta.y);
+            //move by delta
-
+            entity.move(ref.body.x - ref.x, ref.body.y - ref.y);
-            //save last position
-            ref.position.set(entity);
-
-            //add delta velocity - this doesn't work very well yet
-            //entity.vel().add(ref.velocity).sub(ref.lastVelocity);
         }
     }
 
@@ -129,7 +89,6 @@ public class PhysicsProcess implements AsyncProcess{
     public void reset(){
         if(physics != null){
             refs.clear();
-            physics.dispose();
             physics = null;
         }
     }
@@ -138,17 +97,83 @@ public class PhysicsProcess implements AsyncProcess{
     public void init(){
         reset();
 
-        physics = new Physics(new Vec2(), true);
+        physics = new PhysicsWorld(Vars.world.getQuadBounds(new Rect()));
     }
 
     public static class PhysicRef{
         public Physicsc entity;
-        public Body body;
+        public PhysicsBody body;
-        public Vec2 lastPosition = new Vec2(), delta = new Vec2(), velocity = new Vec2(), lastVelocity = new Vec2(), position = new Vec2();
+        public float x, y;
 
-        public PhysicRef(Physicsc entity, Body body){
+        public PhysicRef(Physicsc entity, PhysicsBody body){
             this.entity = entity;
             this.body = body;
         }
     }
+
+    //world for simulating physics in a different thread
+    public static class PhysicsWorld{
+        //how much to soften movement by
+        private static final float scl = 1.25f;
+
+        private final QuadTree<PhysicsBody> tree;
+        private final Seq<PhysicsBody> bodies = new Seq<>(false, 16, PhysicsBody.class);
+        private final Rect rect = new Rect();
+        private final Vec2 vec = new Vec2();
+
+        public PhysicsWorld(Rect bounds){
+            tree = new QuadTree<>(new Rect(bounds));
+        }
+
+        public void add(PhysicsBody body){
+            bodies.add(body);
+        }
+
+        public void remove(PhysicsBody body){
+            bodies.remove(body);
+        }
+
+        public void update(){
+            tree.clear();
+            for(int i = 0; i < bodies.size; i++){
+                PhysicsBody body = bodies.items[i];
+                body.collided = false;
+                tree.insert(body);
+            }
+
+            for(int i = 0; i < bodies.size; i++){
+                PhysicsBody body = bodies.items[i];
+                body.hitbox(rect);
+                tree.intersect(rect, other -> {
+                    if(other.flag != body.flag || other == body || other.collided) return;
+
+                    float rs = body.radius + other.radius;
+                    float dst = Mathf.dst(body.x, body.y, other.x, other.y);
+
+                    if(dst < rs){
+                        vec.set(body.x - other.x, body.y - other.y).setLength(rs - dst);
+                        float ms = body.mass + other.mass;
+                        float m1 = other.mass / ms, m2 = body.mass / ms;
+
+                        body.x += vec.x * m1 / scl;
+                        body.y += vec.y * m1 / scl;
+                        other.x -= vec.x * m2 / scl;
+                        other.y -= vec.y * m2 / scl;
+                    }
+                });
+                body.collided = true;
+            }
+        }
+
+        public static class PhysicsBody implements QuadTreeObject{
+            public float x, y, radius, mass;
+            public int flag = 0;
+            public boolean collided = false;
+
+            @Override
+            public void hitbox(Rect out){
+                out.setCentered(x, y, radius * 2, radius * 2);
+            }
+        }
+    }
 }

core/src/mindustry/content/UnitTypes.java

@@ -304,7 +304,7 @@ public class UnitTypes implements ContentList{
 
             mineTier = 2;
             mineSpeed = 5f;
-            commandLimit = 15;
+            commandLimit = 8;
 
             abilities.add(new ShieldFieldAbility(20f, 40f, 60f * 5, 60f));
             ammoType = AmmoTypes.power;
@@ -347,7 +347,7 @@ public class UnitTypes implements ContentList{
             armor = 9f;
             landShake = 2f;
 
-            commandLimit = 18;
+            commandLimit = 10;
             mechFrontSway = 0.55f;
             ammoType = AmmoTypes.power;
 
@@ -402,7 +402,7 @@ public class UnitTypes implements ContentList{
             canBoost = true;
             landShake = 4f;
 
-            commandLimit = 20;
+            commandLimit = 8;
 
             weapons.add(new Weapon("vela-weapon"){{
                 mirror = false;
@@ -452,7 +452,7 @@ public class UnitTypes implements ContentList{
             landShake = 1.5f;
             rotateSpeed = 1.5f;
 
-            commandLimit = 20;
+            commandLimit = 8;
 
             legCount = 4;
             legLength = 14f;
@@ -1312,7 +1312,7 @@ public class UnitTypes implements ContentList{
             payloadCapacity = (5.3f * 5.3f) * tilePayload;
             buildSpeed = 4f;
             drawShields = false;
-            commandLimit = 25;
+            commandLimit = 6;
 
             abilities.add(new ForceFieldAbility(140f, 4f, 7000f, 60f * 8), new HealFieldAbility(130f, 60f * 2, 140f));
         }};

core/src/mindustry/entities/PhysicsWorld.java

@@ -1,48 +0,0 @@
-package mindustry.entities;
-
-import arc.math.geom.*;
-import arc.math.geom.QuadTree.*;
-import arc.struct.*;
-
-public class PhysicsWorld{
-    private QuadTree<PhysicsBody> tree;
-    private Seq<PhysicsBody> bodies = new Seq<>(false, 16, PhysicsBody.class);
-    private Rect rect = new Rect();
-
-    public PhysicsWorld(Rect bounds){
-        tree = new QuadTree<>(new Rect(bounds));
-    }
-
-    public void add(PhysicsBody body){
-        bodies.add(body);
-    }
-
-    public void remove(PhysicsBody body){
-        bodies.remove(body);
-    }
-
-    public void update(){
-        tree.clear();
-        for(int i = 0; i < bodies.size; i++){
-            tree.insert(bodies.items[i]);
-        }
-
-        for(int i = 0; i < bodies.size; i++){
-            PhysicsBody body = bodies.items[i];
-            body.hitbox(rect);
-            tree.intersect(rect, other -> {
-
-            });
-        }
-    }
-
-    public static class PhysicsBody implements QuadTreeObject{
-        public float x, y, xv, yv, radius, mass;
-        public int flag = 0;
-
-        @Override
-        public void hitbox(Rect out){
-            out.setCentered(x, y, radius * 2, radius * 2);
-        }
-    }
-}

core/src/mindustry/entities/comp/CommanderComp.java

@@ -73,7 +73,7 @@ abstract class CommanderComp implements Unitc{
     void command(Formation formation, Seq<Unit> units){
         clearCommand();
 
-        float spacing = hitSize() * 1f;
+        float spacing = hitSize() * 0.65f;
         minFormationSpeed = type().speed;
 
         controlling.addAll(units);

core/src/mindustry/type/UnitType.java

@@ -317,7 +317,7 @@ public class UnitType extends UnlockableContent{
 
     public void draw(Unit unit){
         Mechc mech = unit instanceof Mechc ? (Mechc)unit : null;
-        float z = unit.elevation > 0.5f ? (lowAltitude ? Layer.flyingUnitLow : Layer.flyingUnit) : groundLayer + Mathf.clamp(hitSize /4000f, 0, 0.01f);
+        float z = unit.elevation > 0.5f ? (lowAltitude ? Layer.flyingUnitLow : Layer.flyingUnit) : groundLayer + Mathf.clamp(hitSize / 4000f, 0, 0.01f);
 
         if(unit.controller().isBeingControlled(player.unit())){
             drawControl(unit);

settings.gradle

@@ -33,7 +33,6 @@ if(!hasProperty("release")){
         ':Arc:extensions:recorder',
         ':Arc:extensions:arcnet',
         ':Arc:extensions:packer',
-        ':Arc:extensions:box2d',
         ':Arc:extensions:g3d',
         ':Arc:extensions:fx',
         ':Arc:natives',
@@ -43,9 +42,6 @@ if(!hasProperty("release")){
         ':Arc:natives:natives-freetype-desktop',
         ':Arc:natives:natives-freetype-android',
         ':Arc:natives:natives-freetype-ios',
-        ':Arc:natives:natives-box2d-desktop',
-        ':Arc:natives:natives-box2d-android',
-        ':Arc:natives:natives-box2d-ios',
         ':Arc:backends',
         ':Arc:backends:backend-sdl',
         ':Arc:backends:backend-android',