Rotation based on Mouse-Position

nor0x

Hello Community ;)

I am working on a little game (similar to frozen bubble), and I have a problem with the rotation of the Arrow, which shows the direction to shoot.
The arrow on the bottom of the image, should alwas point to the current position of the mouse-cursor.

!http://www.abload.de/img/box2d_rotationinuli.png(rotation)!

I already search in this forum, right now I have this code to rotate the arrow, but the rotation-behavior is quite strange.

@var a1 = mouseX - arrowBody.x;
var b1 = mousey - arrowBody.y;
var angle = Math.atan2(a1,b1);
// var angle = angle / (Math.PI / 180);
arrow.rotation = angle;@

As you can see in the code, I also tried to work with degrees, but nothing worked for me.

I hope you can help me!
Thank you,
nor0x

steno

If you are using qt 4.8.4 or older, you might be experiencing this bug.

"qAtan2 bug":https://bugreports.qt-project.org/browse/QTBUG-27090

nor0x

Thank you very much,

I am using V-Play-Engine with QT 4.7.4 - i will update my Installation, and post if it helped

steno

I think just reversing your parameters and converting to degres should be enough.

nor0x

bq. I think just reversing your parameters and converting to degres should be enough.

Thanks for the reply, i changed my code to:

@var angle = Math.atan2(b1,a1)
arrowBody.rotation = angle * 180 / Math.PI@

The rotation works better than before but it starts at a wrong point.

The picture shows the behavior of my arrow, when I click near the orange-point the arrow changes from straight vertical to an incorrect angle!
!http://www.abload.de/img/rotation2bguhu.png(Rotation)!

Thank you

vishu

hi,,,
i am beginner to QML i too have same problem i am creating small applications in that whenever i change the cursor position all my fishes has to come to eat the cursor point.. i am able to move it with cursor position but unable to move with direction.

kindly help me

Thanku