Physics WIP + Documentation

GTA2.NET/GTA2.NET/GTA2.NET Core/Logic/Car.cs

@@ -28,17 +28,30 @@
 using FarseerPhysics.Collision.Shapes;
 using FarseerPhysics.Common;
 using FarseerPhysics.Dynamics;
+using FarseerPhysics.Dynamics.Contacts;
 using FarseerPhysics.Dynamics.Joints;
 using FarseerPhysics.Factories;
 using Hiale.GTA2NET.Core.Helper;
 using Microsoft.Xna.Framework;
 
 namespace Hiale.GTA2NET.Core.Logic
 {
+    /// <summary>
+    /// Represents a car.
+    /// See Car physics.png:
+    /// Steering mechanism joints - The front wheels rotate on these points. Angle is locked from -35 degrees to +35 degrees (subject to change).
+    /// Front wheels - Are needed to determine in which angle the car should drive; not displayed to the player, only exists as physics engine object
+    /// Sprite area (whole gray area) - Any sprite data is drawn on this layer. Usually bigger than the collsions box, because it can also contain door information for example.
+    /// Collision box - determines the area for collision detection. Usually smaller than the sprite area.
+    /// Rear wheels - Fixed angle wheels. Invisible. Force is applied to these wheels which moves the whole car as a consequence,
+    /// </summary>
     public class Car : Vehicle
     {
         public CarInfo CarInfo { get; private set; }
 
+        private const float angleLock = 35f;
+        private const float lockToLockTime = 500; //from lock to lock in 0.5 seconds
+
         private Body _body;
         private PolygonShape _shape;
         private PolygonShape _spriteShape;
@@ -65,6 +78,8 @@ public override float CollisionHeight
             get { return _collisionHeight; }
         }
 
+        public override event EventHandler Collided;
+
         public override Vector2 CollisionTopLeft
         {
             get { return _shape.Vertices[0].ToBlockUnits(); }
@@ -162,6 +177,7 @@ public override void CreateBody(World world, float width, float height)
             vertices.Add(new Vector2(-halfWidth, halfHeight)); //Bottom-Left
             _shape = new PolygonShape(vertices.ToMeters(), 0.1f);
             var fixture = _body.CreateFixture(_shape); //shape, density
+            fixture.OnCollision += OnCollision;
 
             //SpriteId Fixture
             //var spriteHalfWidth = (float) CarInfo.Sprite.Rectangle.CollisionWidth/2; //ToDo
@@ -213,6 +229,13 @@ public override void CreateBody(World world, float width, float height)
             _frontRightJoint = CreateJoint(_body, wheel.Body, wheelOffsetPosition, world);
         }
 
+        private bool OnCollision(Fixture fixtureA, Fixture fixtureB, Contact contact)
+        {
+            if (Collided != null)
+                Collided(this, EventArgs.Empty);
+            return true;
+        }
+
         private static RevoluteJoint CreateJoint(Body carBody, Body wheelBody, Vector2 anchor, World world)
         {
             var joint = JointFactory.CreateRevoluteJoint(carBody, wheelBody, Vector2.Zero);
@@ -232,14 +255,13 @@ public override void Update(ParticipantInput input, float elapsedTime)
             Position3 = new Vector3(position.X, position.Y, Position3.Z);
             foreach (var wheel in _wheels)
             {
-                wheel.UpdateFriction();
-                wheel.UpdateDrive(input.Forward);
+                wheel.Update(input.Forward, elapsedTime);
             }
 
             //control steering
-            var lockAngle = MathHelper.ToRadians(35);
-            var turnSpeedPerSec = MathHelper.ToRadians(320); //from lock to lock in 0.25s
-            var turnPerTimeSpep = turnSpeedPerSec / 60f;
+            var lockAngle = MathHelper.ToRadians(angleLock);
+            var turnSpeedPerSec = MathHelper.ToRadians((angleLock*2)/(lockToLockTime/1000));
+            var turnPerTimeSpep = turnSpeedPerSec*elapsedTime;
             var desiredAngle = 0f;
             if (input.Rotation < 0)
                 desiredAngle = lockAngle;

GTA2.NET/GTA2.NET/GTA2.NET Core/Logic/Vehicle.cs

@@ -49,6 +49,8 @@ protected Vehicle(Vector3 startUpPosition, float startUpRotation) : base(startUp
             set { throw new NotSupportedException("Set Position3 instead."); }
         }
 
+        public abstract event EventHandler Collided; //ToDo: change EventHandler to something more specific...
+
         public abstract Vector2 CollisionTopLeft { get; }
         public abstract Vector2 CollisionTopRight { get; }
         public abstract Vector2 CollisionBottomRight { get; }

GTA2.NET/GTA2.NET/GTA2.NET Core/Logic/Wheel.cs

@@ -111,23 +111,18 @@ public Vector2 GetForwardVelocity()
             return Vector2.Dot(currentForwardNormal, Body.LinearVelocity)*currentForwardNormal;
         }
 
-        public void UpdateFriction()
+        public void Update(float acceleration, float elapsedTime)
         {
             //angulat velocity
             Body.ApplyAngularImpulse(_mCurrentTraction * 0.1f * Body.Inertia * -Body.AngularVelocity);
-            
+
             //forward linear velocity
             var currentForwardNormal = GetForwardVelocity();
-            Geometry.SafeNormalize(ref currentForwardNormal);
             float currentForwardSpeed = Geometry.SafeNormalize(ref currentForwardNormal);
-            float dragForceMagnitude = -0.25f*currentForwardSpeed;
+            float dragForceMagnitude = -0.25f * currentForwardSpeed;
             dragForceMagnitude *= _mCurrentDrag;
             Body.ApplyForce(_mCurrentTraction * dragForceMagnitude * currentForwardNormal, Body.WorldCenter);
 
-        }
-
-        public void UpdateDrive(float acceleration)
-        {
             //find desired speed
             float desiredSpeed = 0;
             if (acceleration > 0)
@@ -136,8 +131,8 @@ public void UpdateDrive(float acceleration)
                 desiredSpeed = _mMaxBackwardSpeed;
 
             //find current speed in forward direction
-            var currentForwardNormal = Body.GetWorldVector(Vector2.UnitY);
-            float currentSpeed = Vector2.Dot(GetForwardVelocity(), currentForwardNormal);
+            var worldVector = Body.GetWorldVector(Vector2.UnitY);
+            float currentSpeed = Vector2.Dot(GetForwardVelocity(), worldVector);
 
             //apply necessary force
             float force = 0;
@@ -151,7 +146,7 @@ public void UpdateDrive(float acceleration)
 
             float speedFactor = currentSpeed/120;
 
-            var driveImpulse = (force/60f)*currentForwardNormal;
+            var driveImpulse = (force*elapsedTime)*worldVector;
             if (driveImpulse.Length() > _mMaxLateralImpulse)
                 driveImpulse *= _mMaxLateralImpulse/driveImpulse.Length();
 

GTA2.NET/GTA2.NET/GTA2.NET/MainGame.cs

@@ -242,7 +242,7 @@ protected override void Update(GameTime gameTime)
             var elapsedGameTime = (float)gameTime.ElapsedGameTime.TotalSeconds;
 
             var input = new PlayerInput();
-            HandleInput(ref input);
+            HandleInput(ref input, controller);
             ChasingObject.Update(input, elapsedGameTime);
 
 
@@ -286,25 +286,25 @@ private void UpdateObjects(float elapsedGameTime)
 
 
 
-        private void HandleInput(ref PlayerInput playerInput)
+        private void HandleInput(ref PlayerInput playerInput, XboxController controller)
         {
             //Vector3 cameraPos = BaseGame.CameraPos;
-            if (Input.KeyboardUpPressed)
+            if (Input.KeyboardUpPressed || controller.RightTrigger > 0)
             {
                 //_playerForwardDelta = ForwardScalar * _elapsedGameTime;
                 playerInput.Forward = 1;
             }
-            if (Input.KeyboardDownPressed)
+            else if (Input.KeyboardDownPressed || controller.LeftTrigger > 0)
             {
                 //_playerForwardDelta = -ForwardScalar * _elapsedGameTime;
                 playerInput.Forward = -1;
             }
-            if (Input.KeyboardLeftPressed)
+            if (Input.KeyboardLeftPressed || controller.IsDPadLeftPressed)
             {
                 //_playerRotationDelta = -RotationScalar * _elapsedGameTime;
                 playerInput.Rotation = 1;
             }
-            if (Input.KeyboardRightPressed)
+            else if (Input.KeyboardRightPressed || controller.IsDPadRightPressed)
             {
                 //_playerRotationDelta = RotationScalar * _elapsedGameTime;
                 playerInput.Rotation = -1;