Calculate point in rotated rectangle

cocos2d-x C++
1

Hi, I need your help. How I can caculate red dot position in the layer. I know the rectangle position at (0,5, 0.5), it’s bounding box and rotation.

Any ideas ? Thanks.

2

There are a few different ways, but perhaps the most direct would be…

    auto v = Vec3(-.5f, 0, 0); // relocate so that 0,0 is the origin
    
    Mat4 m;
    Mat4::createRotationZ(angle, &m);
    
    auto result = m * v;

Note that the angle is in radians.

3

You could also use Vec2::rotateByAngle

    Vec2 oldPoint, center;
    Vec2 newPoint = oldPoint.rotateByAngle(center, angleInRadians);
2 Likes