Posted 09 February 2010 - 12:55 PM
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
Posted 09 February 2010 - 01:40 PM
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.
Posted 10 February 2010 - 11:41 AM
I tried it but i don't know how to solve the equation with unknown variable theta.Any help guys
Posted 10 February 2010 - 11:56 PM
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:
Vector2 move; 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:
int degrees; 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 ;)
Posted 11 February 2010 - 12:10 AM
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 page useful, particularly the last section "Angle of Launch".
Posted 11 February 2010 - 04:55 AM
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 speed.
Help me guys.Thanks in advance.
Posted 11 February 2010 - 01:09 PM
Posted 11 February 2010 - 01:41 PM
Posted 12 February 2010 - 01:02 PM
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 lot.
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