29/03/17 (2 Hour Spent)
The first order of today after housework and a coffee, is getting my mouse input to try and get the firing direction and have the arrow point to where the mouse is at.
I could try and raycast to the parts of the course, but, there may be times where I donât want to apply a direction at an angle other than on the horizontal. It would also cause issues if the mouse pointer wasnât always over a part of the course. So ill remove that out of the equation and just use a ground plane.
The only other thing that I might have to think about later on is if the ball is at the bottom of a slope.
do I apply the force in the B, direction or just stick to A to make things simpler and use the same throughout.
If it causes any issues once I get a prototype done, then Iâll have to look over it again and rethink, but for now, ill stick with the horizontal as the force direction.
Ive done something similar in the past with raycasting where a plane is drawn through the player and I get the hitpoint of the ray, like below.
Where I want to find a point on the same Y plane as the ball, and then have whatever im using as a visual pointer look towards it.
Now what I want is this plane to always be straight through the centre of the ball and the plane always horizontal.
Before I go finding out how to rotate anywhere, I need something to rotate.
So heres what im using, and ill explain why and what I was thinking about.
So
GolfBall is the main ball and thatâs going to do all the rolling about etc.
Ive added a child empty,
AimPointer, this is the one that im going to rotate around, so it doesnât affect how the ball behaves. Not much good in having an empty with nowt in it.
So ive made a little arrow in Paint, and imported and set to a sprite, and added this sprite as a child to AimPointer. Now ive orientated the arrow sprite to point in the same direction as the Z axis of the AimPointer.
Reason? Well, once I find the direction with raycasting, I can use Transform.LookAt() to rotate the AimPointer. And using that lookat(), it always points the forward Z axis to the target, hence the reason the arrow sprite is rotated to point down the Z axis of the AimPointer object. And it wont affect how the ball rotates in case of dodgy physics behaviour.
And to answer another question I had, surely as the ball rolls it will affect the rotation of the arrow?
But, no, not really⌠because A: the ball will not be rolling when the arrow is visible. And B: the arrow will always be facing towards the mouse pointers raycasted point on the plane so it will always have the normal facing upwards, and the Z axis pointing towards the mouse each frame.
The raycasting bit was ok, the problem I had was how to get the plane to be at the same Y height as the ball and what size to make it, and generally how to draw it.
Well looking at the docs for Plane and how to create one programmatically
Scripting Reference for Plane
Its as clear as mud on first read, with the constructors
Plane(Vector3 inNormal, Vector3 inPoint)
Plane(Vector3 inNormal, float d)
Plane(Vector3 a, Vector3 b, Vector3 c)
I didnât have a clue what the first lot were the first time, so I went with the the 3 vector points, and created points around the golfball, to what I thought was creating a plane at that size with the corners I specified for the 3 vectors. But testing it it seemed to work no matter how far away I put the mouse.
So I started with this
Plane groundPlane = new Plane(
// just need to declare 3 corner points to create the plane, as it iterpolates the 4th corner.
// doing it this way, creates the plane dead centre of the ball, JUST REMEMBER CW winding for normal.
new Vector3(transform.position.x + 1f, transform.position.y, transform.position.z-1f),
new Vector3(transform.position.x - 1f, transform.position.y, transform.position.z-1f),
new Vector3(transform.position.x + 1f, transform.position.y, transform.position.z+1f));
But after more readingup, I read the part again at the top of the scripting ref, where it said that the plane was infinite size, so the 3 point method I used just basically declared its position and normal direction size was arbitrary.
Back to the scripting reference page for another read once I understood it a bit more and ended up realising I could use this instead
Plane groundPlane = new Plane(Vector3.up, transform.position);
Big difference, a lot more readable and a lot more compacted.
But all that messing about and reading took about an hour to suss out.
The rest of the code was fairly straight forward (grabbed a reference to the AimArrowSprite to use for lookat ) so used the following
(excerpt, full code in repo)
// used for raycasting out, logs hit distance
float rayDistance;
if(groundPlane.Raycast(ray, out rayDistance))
{
Vector3 point = ray.GetPoint(rayDistance);
// so i can see the ray
Debug.DrawLine(ray.origin, point,Color.red);
// since the plane is at same Y level as ball, set the aim arrow to look at the hit point.
// (always uses the transforms local forward vector, this way the arrow is always flat)
transform.LookAt(point);
}
Works well, so tomorrows job, get the ball to move, and switch on and off the targeting arrow when (if) the ball moves and comes to rest
Good luck with it.
