Camera Angle Of Attack

[SkriK]

Let's say i have a camera at 500 Z-offset that i want it's angle of attack to change according to a single unit's location.

As shown in this image, when the unit is far away, the angle of attack is less, but when closer it points more downward. How can i trigger this?

*Thumbs up for imba freehand drawing :>*

 

[Marcelo Hossomi]

You might want to use trigonometrical functions.

Pay attention to the right triangle formed by the camera (C), the unit (U) and the point right below the camera (where there's a 90º angle). Let's call this point (P). You'll work basically with two sides of it: CP and UP, which are the two catheti. So, the tangent of the angle UCP is UP/CP.

Using the Arctangent function, you can calculate this angle:
atan(UP/CP) = UCP

Now I don't remember which direction is the 0-degree for cameras...

 

[SkriK]

Ok thanks, gonna try it. (If i figure out what you mean )

Angles go like this:

 

[Yixx]

yeah, i had some problems with it though,, he is right about the Tangent, though i think he means angle PUC/CUP (the AoA is angle between ground and camera-eye with camera-target as mid right?).

I fixed my AoA problems by doing this:

set AoA = AoA + 1.5*bj_PI

Where the AoA is in radians. Dunno if it is the right thing to do, but it worked! =D

 

[Marcelo Hossomi]

I'll try to explain it better...

@Yixx: yes, thanks xD

Look at the attached triangle.

U = Unit
C = Camera
P = Point

UP = Distance from the unit to the camera position (x/y position only, not z)
CP = Camera Z offset/height (500, right?)

As the camera AoA is determined by the angle formet between the camera and the ground, as Yixx stated, you can use the Tangent relationship:

tan(PUC) = CP/UP

Which you can calculate, as you can have CP and UP
So if you use the inverse function atan, you'll get the angle:

atan(CP/UP) = PUC

However this will return in radians. To convert to degrees, multiply it by 180/pi.

 

[Yixx]

But this will return a value like this: (dunno right english word)
0<= angle < 90 (there can be NO 90 degrees (1/2*PI) outcome from Atan, if you wanna know ill explain later)
But AoA has a whole different system of angles. On the ground is 0/360, and it will count UP when going LOWER into the ground, and it will count DOWN (from 360) when going Higher from the ground. Meaning that you will have to add 270 degrees (1.5*PI) to get the value for a good AoA.

"Meaning that you will have to add 270 degrees (1.5*PI)". The statement in my first post must be adjusted, not substract but indeed ADD.

 

[Marcelo Hossomi]

That's because there will be a division by 0 when the unit is right below the camera. An if-statement should be made to prevent this from happening then ^^

I suspected of the direction problem you said... I was trying to find out why the hell you subtracted/added 1.5*pi xD

 

[Yixx]

division by 0 crashes thread so,,

But i hope you now understand the 1.5*PI Otherwise, try yourself to set the AoA to an angle that comes freshly out of the Atan lol. It will fuck up,, so i started experimenting with adding values. And when i came to 1.5*PI, i was like "WTF that is SO logical xD"