How do you create Z-Axis Projectile Movement?

[Kid_Roleplay]

So not long ago, I inquired on how to make a custom 8 directional movement for a project I'm working on, and a scholarly gentleman helped me out on some pointers! Only, now I'm needing to figure out how to incorporate a custom projectile movement which will raise and fall based on altitudes of what's firing versus what's being fired at (said altitudes stored in an Alterable Value of course).

You have to store your Xpos and Ypos as alt. values and operate sin-cos calculations on that,
X and Y object's positions are pixel integers and won't work well with decimal operators (sin_cos)


start of frame >>
set Xpos_Val to X position
set Ypos_Val to Y position

on movement >>
set Xpos_Val to Xpos_Val + (speed*Cos(angle))
set Ypos_Val to Ypos_Val - (speed*Sin(angle))
set X position to Xpos_Val
set Yposition to Ypos_Val

So now I need to have an altitude check that will also affect projectile speed (like, if something's shooting straight up, then there should be no X or Y speed for example) and be able to calculate how much to gradually lift or drop said projectile in order to hit whatever's being aimed at.

[schrodinger]

Thanks for the gentleman

This may be not so straightforward,
or completely straightforward, depending mainly on this:

you want a straight-line between projectile and target,
or a "parabolic" kinda "esteem" from starting to end position based on projectile speed, starting angle, gravity...?

(Please tell "straight-line" )

[Kid_Roleplay]

=P

Straight line is what I'm going for at the moment. Bullet's for now. Point A to point B. Although I may eventually add in something like guided missiles, especially for a particular weapon I'm going to be adding down the line.

Although I also plan on having said bullets be... quite fast, but if it can work for any given speed, that would be dandy!

[schrodinger]

Since you also want high speed,
I would suggest looking at this example:
http://community.clickteam.com/threads/93553-The-exact-coordinates-of-the-collision-bullets

Having higher speeds without fastloops may easily end up in wrong collision detection.

As long as your code won't include hundreds of bullet at the same time, this should be fine.

[Kid_Roleplay]

Ahh. Well I'm less needing to know about the speed and collisions and more about just getting the Z-axis to work. Namely, how much to raise or lower a projectile sent towards objects with altitudes based on an Alterable Value, and slowing down X/Y speed accordingly, while also limiting how much the Z-axis would raise and lower based on the same maximum speed (for instance, raising and lowering as fast as, and up into, the max speed of a projectile if all objects were at the same altitude).

This is of course for something isometric in the works, using the invisible layer method.

[schrodinger]

Oh, wait... you're talking about isometric trajectories?
That's a completely different situation then

So you have already calculated X-Y axis trajectories, to make bullet follow straight isometric directions,
and you want to alter this trajectory with an additional "Z" axis perpendicular to the ground,
so to make them resemble going vertically up/down?

Could you provide a little sketch or something to clarify?
May be a challenging task, however, don't know if I would be up to it

[Kid_Roleplay]

It's actually easier than it sounds since I'm working with the invisible layer. I have objects that use a custom 8-direction movement on the invisible layer, and on visible layers, there are objects that correspond with their invisible counterparts to mimic the 2:1 ratio of isometric perspective. Altitude is currently handled by an Alterable Value.

Set X position to X( "Invisible Object" )
Set Y position to ( Y( "Invisible Object" ) / 2 ) - Altitude( "Invisible Object" )

That's been working swell so far. What I need now is something that can adjust the Altitude and X/Y speed of a traveling bullet object when being shot from one Invisible Object at another, which have differing Altitude values.

[schrodinger]

I guess some trigonomerty should do the job then,
but since I'm not comfortable with this invisible layer setup (seems a clever idea!)
I can't delve too deeply in the argument.

I *think*
you should basically replicate what you already do with X,Y positions,
and substitute in your calculations "X with Y" and "Y with Z"
(think of looking at the scene from a side: Z axis is vertical position (screen Y), Y axis is horizontal position (screen X ))

[Kid_Roleplay]

Sadly, when it comes to looking at it like that, that's when I just plain don't get it. But I'll attach what I mean when I'm referring to the invisible layer.

MessingAround.mfa

[schrodinger]

Very nice!
Here's a quick code for a projectile (press spacebar):

MessingAround_1.mfa

If you clarify how you would like to make it change its height we could try something
(you basically just should alter projectile "height" value anyway...)


EDIT: now I remember you were asking to adjust trajectory between two objects at different heights
here's what you could try:
-calculate the angular difference between the two objects (ATan2 (Z2-Z1,Y1-Y2))
-move the bullet with the code you're already using (or the one I wrote in the example) and
instead of altering X-Y coordinates, you should alter only height value by sin(angular_difference) * bullet speed

Just as an untested idea, unfortunately I don't have the time to test right now