I'm trying to calculate the ending x,y of my object. I have the starting x,y and the angle in radians and the speed

this is what I'm trying:


the result is almost as if everything is wildly exagerated.

does anyone know how to calculate this correctly?

Seems like you'd want to add deltaX/Y to startingX/Y instead of multiplying them together.

Also, why multiply the *speed* by cos and sin of the angle? What are you trying to do there? Should the translation be affected by rotation?

I usually express this kind of things by matrix multiplication. It scales better to more complex situations.

I have a facing vector instead of a facing angle. The plus side is you don't need to cos and sin constantly, only when they turn. Then when you want to move somebody you just do
movement=[facing scale:speed];
[position add:movement];

I just made up arbitrary function names but you can probably get the point.
When you want to turn all you need to do is rotate the facing vector by X radians negative for a left turn, positive for a right turn. You can rotate a vector using CGAffineTransform functions.

Kazooless Wrote:I'm trying to calculate the ending x,y of my object. I have the starting x,y and the angle in radians and the speed

this is what I'm trying:

Code:

deltaX = cos( rotation ) * speed;
deltaX = startingX * deltaX;
deltaY = sin( rotation ) * speed;
deltaX = startingY * deltaY;

the result is almost as if everything is wildly exagerated.

does anyone know how to calculate this correctly?

I assume this is so that you can move an object on an angle? if so you can use the following code

It's basic trigonometry where the speed is the hypoteneuse and the y is "Opposite" and x is "Adjacent".
looking at a clock 3 o'clock would be 0 (or 360) degree, 12 - 90 (or -270) degrees, 9 - 180 (or -180) degrees, 6 - 270 (or -90) degrees.
speed * cos (rotation)

masdest Wrote:I assume this is so that you can move an object on an angle? if so you can use the following code

Code:

deltaY = sin (rotation) * speed; //this finds the y travel distance
finalY = startingY + deltaY; // this is the location of object on the y plane
deltaX = cos (rotation)  * speed; //this finds the x travel distance
finalX = startingY + deltaY;

It's basic trigonometry where the speed is the hypoteneuse and the y is "Opposite" and x is "Adjacent".
looking at a clock 3 o'clock would be 0 (or 360) degree, 12 - 90 (or -270) degrees, 9 - 180 (or -180) degrees, 6 - 270 (or -90) degrees.
speed * cos (rotation)

That last line should read: