coddding - 9 days ago 5
C++ Question

# c++ calculating 2 points based off 2 other points

Ok, so I'm making this fun little game in c++, unfortunately I'm stuck on making a "radar", I'm stuck on this part

`A`
&
`B`
, the only thing i do not have is
`C`
&
`D`
)

So what i need to do is calculate the two points (
`2d vector`
) of
`C`
&
`D`
, they need to be in the placement like in the lil pic i made shown above (sorry, i know it's bad).

`B`
will rotate around
`A`
so i need to calculate the position of
`C`
&
`D`
based on the rotation of
`B`
. I am going to create a triangle (e.g. draw a line from
`C`
to
`D`
,
`D`
to
`B`
&
`B`
to
`A`
)

`A`
could be thought of as the center of the bottom line of the triangle, this is like the base of everything, everything rotates around
`A`
, and the position of
`C`
&
`D`
need to be calculated according to how much
`B`
has rotated around
`A`
.

What would be like the best way to make a lil function for this calculation?
e.g.

``````inline float returnDPoint(float A, float B)
{
float dPoint;
//calculate point of D based off A & B
return dPoint;
}

inline float returnCPoint(float A, float B)
{
float cPoint;
//calculate point of C based off A & B
return cPoint;
}
``````

Hopefully i have worded my question well enough, thanks for the read!

Since you are looking for rotations by 90°, you don't need to use expensive functions such as `atan2`, `sqrt`, etc. A simple alternative would be:
``````diffx = bx - ax;