Trajectory aim, how do i do it?

Questions & Answers
1

Hi, Im using a script I found somewhere in this forum, Its good enought to get my object (cannon) to follow the mouse direction, but I also need a trejetory line that stop at colision (the walls around the level). I can’t find the answer anywhere, alread tryed messing around with raycast and lineRenderer, but I lack the knowledge on scripting. Anybody have a solution, or at least point me out on the right direction???

here’s the script Im using:

// LookAtMouse will cause an object to rotate toward the cursor, along the y axis.
//
// To use, drop on an object that should always look toward the mouse cursor.
// Change the speed value to alter how quickly the object rotates toward the mouse.

// speed is the rate at which the object will rotate
var speed = 4.0;

function Update () {
    // Generate a plane that intersects the transform's position with an upwards normal.
    var playerPlane = new Plane(Vector3.up, transform.position);

    // Generate a ray from the cursor position
    var ray = Camera.main.ScreenPointToRay (Input.mousePosition);

    // Determine the point where the cursor ray intersects the plane.
    // This will be the point that the object must look towards to be looking at the mouse.
    // Raycasting to a Plane object only gives us a distance, so we'll have to take the distance,
    //   then find the point along that ray that meets that distance.  This will be the point
    //   to look at.
    var hitdist = 0.0;
    // If the ray is parallel to the plane, Raycast will return false.
    if (playerPlane.Raycast (ray, hitdist)) {
        // Get the point along the ray that hits the calculated distance.
        var targetPoint = ray.GetPoint(hitdist);

        // Determine the target rotation.  This is the rotation if the transform looks at the target point.
        var targetRotation = Quaternion.LookRotation(targetPoint - transform.position);

        // Smoothly rotate towards the target point.
        transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, speed * Time.deltaTime);
    }
}
2

I don’t know if this is exactly what you’re looking for, but you can use the LineRenderer component to add a ray from the object to the target. Add a LineRenderer (menu Component/Miscellaneous/Line Renderer) to your object and modify the script like below:

private var lineRenderer : LineRenderer;

function Start() {
     lineRenderer = GetComponent(LineRenderer);
     lineRenderer.SetColors(Color.red, Color.red);
     lineRenderer.SetWidth(0.1,0.1);
     lineRenderer.SetVertexCount(2);
}

// speed is the rate at which the object will rotate
var speed = 4.0;

function Update () {

    // Generate a plane that intersects the transform's position with an upwards normal.
    var playerPlane = new Plane(Vector3.up, transform.position);
    // Generate a ray from the cursor position
    var ray = Camera.main.ScreenPointToRay (Input.mousePosition);
    // Determine the point where the cursor ray intersects the plane.
    // This will be the point that the object must look towards to be looking at the mouse.
    // Raycasting to a Plane object only gives us a distance, so we'll have to take the distance,
    //   then find the point along that ray that meets that distance.  This will be the point
    //   to look at.
    var hitdist = 0.0;
    // If the ray is parallel to the plane, Raycast will return false.
    if (playerPlane.Raycast(ray, hitdist)) {
        // Get the point along the ray that hits the calculated distance.
        var targetPoint = ray.GetPoint(hitdist);
        // Determine the target rotation.  This is the rotation if the transform looks at the target point.
        var targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
        // Smoothly rotate towards the target point.
        transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, speed * Time.deltaTime);
    } else {
        targetPoint = transform.position;
    }
    lineRenderer.SetPosition(0, transform.position);
    lineRenderer.SetPosition(1, targetPoint);
}

EDITED: You can stop the ray at walls or other obstacles simply by doing a Linecast from transform.position to targetPoint, and replacing the later with the hit point (if any):

...
        transform.rotation = Quaternion.Slerp(transform.rotation, targetRotation, speed * Time.deltaTime);
        // shorten the ray if it's hitting some obstacle:
        var hit: RaycastHit;
        if (Physics.Linecast(transform.position, targetPoint, hit)){
            targetPoint = hit.point;
        }
    } else {
        targetPoint = transform.position;
    }
    lineRenderer.SetPosition(0, transform.position);
    lineRenderer.SetPosition(1, targetPoint);
}