C/C++ How do I rotate a 2D shape in C++?

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To rotate a shape in a 2D space around a center point, a specific formula is used. For a point (x, y) rotated by an angle θ around the origin (0,0), the new coordinates (x', y') can be calculated using the formulas: x' = x * cos(θ) - y * sin(θ) and y' = x * sin(θ) + y * cos(θ). In the example provided, rotating the line defined by points P1(-1,-1) and P2(1,1) by 45 degrees results in new coordinates P1(1,-1) and P2(-1,1), maintaining the center at C(0,0). The discussion highlights the importance of understanding these rotation formulas for effective 2D programming in C++.
sarah22
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I'm creating a C++ 2D program to practice my 2D skills. I'm almost done with everything but I'm stuck on this crap. Is there any formula on how to rotate a shape?

Example:

I have a line P1(-1,-1) P2(1,1)

If I rotate it by 45 degrees, I'll get a P1(1,-1) P2(-1,1). By the way, it should not leave its center which is C(0,0).
 
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http://www.cgafaq.info/wiki/2D_Point_Rotation
 
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Ok thanks I got it.
 

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