protected override void Execute(int execID, EntityID entity, ref VelocityComponent velo, ref TransformComponent trans)
{
if (velo.Velocity == Vector3.zero)
{
return;
}
Vector3 newPos = trans.Matrix.Position + velo.Velocity * deltaTime.Value;
Vector3 dir = FastNormalize(velo.Velocity);
trans.Matrix = Float3x4.FromPositionAndForward(newPos, dir);
}
private void FireProjectile(ref ProjectileSpawnerComponent spawner, ref TransformComponent turretTrans)
{
const float INVERSE_PROJECTILE_SPEED = 1f / 100f;
Vector3 turretPos = turretTrans.Matrix.Position;
Vector3 targetPos = context.GetComponent <TransformComponent>(spawner.Target.Value).Matrix.Position;
Vector3 targetVelo = context.GetComponent <VelocityComponent>(spawner.Target.Value).Velocity;
float distanceEst = ManhattanDistance(targetPos - turretPos);
float flightTime = distanceEst * INVERSE_PROJECTILE_SPEED;
if (flightTime <= 0f)
{
return;
}
//Aim ahead of the target to compensation for its movement
Vector3 aimTarget = targetPos + targetVelo * flightTime;
//Gather info about the trajectory from the turret to the aim-target
Vector3 toAimTarget = aimTarget - turretPos;
float toAimTargetSqrDist = toAimTarget.sqrMagnitude;
float toAimTargetDist = Mathf.Sqrt(toAimTargetSqrDist); //TODO: See if we can get rid of the SquareRoot usage here
Vector3 toAimTargetDir = toAimTarget * FastInvSqrRoot(toAimTargetSqrDist); //Create normalized vector aiming to toward the aim target
//Speed that the projectile will be traveling at. (NOTE: Its not the same as the configured projectile speed we used
//to estimate the flighttime, thats because the estimate did not compensate for the target velocity yet)
float trajectorySpeed = toAimTargetDist / flightTime;
//Calculate how much gravity we will encounter in the journey
float gravity = ApplyGravitySystem.GRAVITY * flightTime;
//Calculate the 'final' projectileVelocity and include the gravity compensation
Vector3 projectileVelocity = toAimTargetDir * trajectorySpeed + Vector3.down * (gravity * .5f);
//This is used to 'point' the turret, if we want to be cheap we could use the 'toAimTargetDir' but thats not
//really accurate because it doesn't include the gravity compensation yet
Vector3 velocityDir = FastNormalize(projectileVelocity);
//Spawn the projectile entity
var entity = context.CreateEntity();
context.SetComponent(entity, new TransformComponent(Float3x4.FromPosition(turretPos)));
context.SetComponent(entity, new VelocityComponent(velocity: projectileVelocity));
context.SetComponent(entity, new GraphicComponent(graphicID: 2));
context.SetComponent(entity, new AgeComponent());
context.SetComponent(entity, new LifetimeComponent(totalLifetime: 3f));
context.SetTag <ProjectileTag>(entity);
context.SetTag <ApplyGravityTag>(entity);
//Update the turret to face the target
turretTrans.Matrix = Float3x4.FromPositionAndForward(turretTrans.Matrix.Position, velocityDir);
}