The effects of the forces applied with this function are accumulated at the time of the call. Specifying the ForceMode mode allows the type of force to be changed to an Acceleration, Impulse or Velocity Change. The equation we used to calculate the angle is not working if we add drag and wind.Force is applied continuously along the direction of the force vector. If you press play you will notice that the bullets are no longer hitting the target. That's all of the external factors we are going to add for now. Vector3 dragVec = aDrag * velocityVec.normalized * -1f Has to be in a direction opposite of the bullet's velocity vector Public static Vector3 CalculateDrag(Vector3 velocityVec)įloat A = Mathf.PI * 0.05f * 0.05f // m^2 Calculate the bullet's drag's acceleration

Public class BulletPhysics : MonoBehaviour You should change these parameters, like mass and area, to fit your bullet. You should also create a new script called BulletPhysics where you can collect all methods that affect the bullets, and add a method that calculates drag. So we have to calculate the acceleration from drag 2 times.ĪcceleartionFactorEuler += BulletPhysics.CalculateDrag(currentVelocity) ĪcceleartionFactorHeun += BulletPhysics.CalculateDrag(vel_E) Vector3 vel_H = currentVelocity + h * 0.5f * (acceleartionFactorEuler + acceleartionFactorHeun) ĭrag force is more complicated to add compared with the wind, because the drag is dependent of the bullet's velocity. acceleartionFactorHeun += BulletPhysics.CalculateDrag(vel_E) Vector3 pos_H = currentPosition + h * 0.5f * (velocityFactor + vel_E) Vector3 vel_E = currentVelocity + h * acceleartionFactorEuler acceleartionFactorEuler += BulletPhysics.CalculateDrag(currentVelocity) Vector3 pos_E = currentPosition + h * velocityFactor VelocityFactor += new Vector3(2f, 0f, 3f) Vector3 velocityFactor = currentVelocity so the bullets also have to use Heuns method

Will give a better result than Euler forward, but will not match Unity's physics engine So just uncomment the line 'velocityFactor += new Vector3(2f, 0f, 3f) ' where the vector is whatever wind you want. If the wind is constant, we can just add it in the same way as we added gravity. Gravity was a constant acceleration and isn't dependent on velocity or position, so we didn't need to care about it when we added gravity. What you need to know if you are going to add realism to the bullet in Heun's method is to calculate the acceleration or velocity with the correct time. In this section we will add factors that will affect the bullet, such as wind and drag.

Bullet force unity