Directions

[git]

Hiyas,

I have a tile-based game, and I'm trying to make the player look in a certain direction (N, NE, E, SE, S, SW, W, NW) according to a mouse click.

I figured out how to do part of it (break up the degrees into 8 directions...and the rest), but how am I supposed to calculate the degrees of the click from the player's position? I have the X/Y point of the person, and X/Y point of the click.

Thanks,

-Git

[kedaman]

depends how you want the player to walk:

  /----->B
 /
A

to get from A to B, in NE and then E, or just straight to B, that may look stupid unless you have 16 or preferably 32 directions. For 8 directions you can simply use > = < comparation between the coordinate components. For more free movement you can use arctangent for offsety/offsetx , it all depends how you want.

[git]

It's only a simple 2D grid game. I've figured out how most of the sight code will work, but the only problem is I can't figure out how to mathematically calculate the amount of degrees the click X/Y is from the source X/Y (eg. if the click is above and to the left, the click X will be bigger, click Y smaller, and it'll be north-east).

How do I do that?

-Git

[kedaman]

as said, you can do it with arctangent, take a look at
http://forums.vb-world.net/showthrea...=anglebyoffset

[Jotaf98]

I'd do it another way:

'How to store the direction:

Dim PlayerDirX As Long, PlayerDirY As Long

...

'To calculate the direction:

'This will return the sign of the mouse's position relative to the center of the screen
PlayerDirX = Sgn(ScreenWidth / 2 - MouseX)
PlayerDirY = Sgn(ScreenHeight / 2 - MouseY)

...

'To move the player:

'PlayerSpeed is the speed of the player, in pixels
PlayerX = PlayerX + PlayerDirX * PlayerSpeed
PlayerY = PlayerY + PlayerDirY * PlayerSpeed

Hope that works. It's the more efficient way to store it in my opinion, the computer doesn't need to know if it's left or right, just to make it work

[git]

Alrighty, I finally figured this out. Basically I needed to find the radians using Atn((X1 - X2) / (Y1 - Y2), and then convert it to degrees...

I ending up figuring out most of the rest...except for one thing. How do I convert a specific angle (preferably in degrees, but also maybe in radians), to X/Y vectors?

Thanks,

-Git

[kedaman]

As a side issue, unless you want the user to directly interact using degrees as angle unit, i'd suggest you use radians only. This is because the trigonometry units in vb are in radians.
To go back to vector components from angle:
X = cos(angle)
Y = sin(angle)

[git]

Thanks. =)

I will still need degrees to sort the angle into one of the 8 directions. There's probably a quicker way to do it, but then it just gets too hard (and I really hate trig... ).

I'll just put the degrees/radians angles into two different variables.

Thanks again for your help.

-Git

[kedaman]

if you want to directly convert to 8'direction variable (from radians) the formula is:
d8=8*rad/(2*pi)

simplified:
d8=1.27323954473516*rad
if you need a phase offset so that you can adjust the direction to not switch when perpendicular to screen, you add a sixteenth revolution
d8=1.27323954473516*rad + 0.392699081698724

[git]

Interesting... I'll have a play with that code in a sec. =)

Btw, with the vector code you supplied (which uses Sin/Cos), is the velocity equal to 1? (the distance from origin points to the origin points + vectors) I'm assuming it is, but I'm not sure, because I don't know very much about this kind of math...

Thanks,

-Git

[kedaman]

yes, i forgot to mention that you will get the unit vector with that formula, By multiplying both components with the original magnitude you get the original vector. The magnitude of a vector is
sqr(x*x+y*y)
In other words, a vector can be interpreted as a direction and a magnitude (angle, length) AKA polar coordinate, as well as dimension components (x,y) AKA cartesian coordinate.

[Jotaf98]

Well, the way you're saying is good only if you want more than 8 directions... but that doesn't seem to be the case, my way handles 8 directions very well and trig is slooow in VB if you use it too much, you know? (I'm not saying your way doesn't work, but since I haven't learned trig in school I had to find another way using simple math )

[kedaman]

Comparatively yes, but there's no extensive use of it anyway so doesn't matter, anyways seems like he wants to work with vectors and only convert to 8 direction for the image sequences.

[Jotaf98]

Ok, no problem

Hey Kedaman, why do you have "4569030913323659107" instead of your member "place" (sorry but I can't find the word right now)? It doesn't seem to happen with anyone else

[kedaman]

if you can find out, you'll get the cool prize http://www.vbforums.com/showthread.p...threadid=76526