Hi to all,
I tried to do cannon projectiles for a game.I know the destination
point where the cannon should land and also have a option of selecting
the speed it travels say from 80 Kph to 100 Kph.I need to know the
angle.How can i find the angle (theta) for the projectile .MY Launching
position is higher than the landing position.Please help me fix
this.Thanks in Advance
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article which explains inverse trajectory determination.
If you want to rotate the projectile sprite in the direction it is
traveling, then subtract your current position by your previous
position. This will give you your linear velocity at that current point.
With this you can calculate the direction of the projectile.
Direction in radians:
dirInRad = atan2(linearVelocity.y, linearVelocity.x);
Convert this value into degrees:
dirInDeg = 180 / pi * dirInRad;
Hope this is the answer you were looking for.
I would also suggest using a physics library if you don’t have the time
to learn the technical stuff. You can google physics library followed by
your language of choice.
I tried it but i don’t know how to solve the equation with unknown
variable theta.Any help guys
I think that we’ll need more information, I was working on this exact
thing today but I need more information to help you.
EDIT: I need information like if you have two points to work from (i.e.
are you using the mouse to control the cannon or what?)
If you have the angle in radians, the move vector is:
float rotation; //The rotation in radians
int speed; //The speed in pixels per frame
move.X = (float) Math.Cos(rotation) * speed;
move.Y = (float) Math.Sin(rotation) * speed;
(The code is in C# because I have been using XNA recently, so C# it is
And the way to get degrees to radians is:
float radians = degrees * PI / 180;
And if you want the angle between two points:
float dx, dy;
float rotation; //Angle in radians
dx = x2 - x1;
dy = y2 - y1;
rotation = (float)Math.Atan2(dy, dx);
I hope I helped some :D
P.S. I am not entirely sure how much of this will actually work, but you
can try it ;)
Nerd Skywalker: maybe it would be more helpful if you said what
additional information you want? ;)
reflex: I can’t seem to see the article you linked to (I “reached a page
that is unavailable for viewing or reached my viewing limit for this
book”). However, OP, you may find this
particularly the last section “Angle of Launch”.
Hi thank you for your reply guys,
I need the angle of elevation.I know the launch point its greater than
the target,I know the destination point where it should land,i know the
speed it travels(its option for users to select the speed between (60 -
100),I need the angle of elevation to reach the destination point.
Ex : Angle of elevation differs based on the value of the variable
Help me guys.Thanks in advance.
Learn some algebra. This is a pretty easy problem to solve yourself; you
already have all the equations. ;)
If I understand your problem correctly, you need to take the locations
of the cannon and where it will land, then plug it in to my first
equation up there. That should work (unless I completely don’t
understand the problem :))
@Reedbeta - The link I posted was a chapter from Game Programming Gems
2, maybe rajesh kumar can try getting hold of a copy. Judging by his
latest reply, the section “Angle of Launch”, or page 207 of Game
Programming Gems 2(if the link works), is exactly what he needs.
reflex thank you for your reply,
I am trying it but i am doing some mistake while solving equation.I
don’t know where i did wrong.Your link and reedbeta both helped me a