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Graphics / Strange behaviour of sf::Shape::SetRotation?

« on: February 09, 2009, 07:17:39 am »

I was writing some code yesterday which was just displaying a white rectangle following the mouse cursor with its orientation. This rectangle was a sf::Sprite, and therefore I set the Center to the middle of the Sprite. Then I then tried to do the same thing with a sf::Shape and created just the same rectangle again. But when I tried to apply the code for the rotation to it, the rectangle was behaving quite strange.
I really have no idea why this is not working, maybe I misunderstood some of the methods the class is offering. So here's the relevant code:

Code: [Select]

sf::Shape shape;
shape.AddPoint(300, 300); //I am aware of sf::Shape::rectangle, but I  think it should work like that anyway.
shape.AddPoint(500, 300);
shape.AddPoint(500, 500);
shape.AddPoint(300, 500);
shape.SetCenter(100,100); //Shouldn't this set the center exactly to the rectangle's middle?

//Event handling etc. is not mentioned here, please don't mention the code indent, it was kind of messed up by copy'n paste from the sourcefile.

if (input.GetMouseX() <= shape.GetPosition().x) {
shape.SetRotation  (-1 * 180 / 3.1415926535 * (atan( static_cast<double> (shape.GetPosition().y - input.GetMouseY()) / static_cast<double> (shape.GetPosition().x - input.GetMouseX()))));
} else {
shape.SetRotation  (-1 * 180 / 3.1415926535 *(atan( static_cast<double> (shape.GetPosition().y - input.GetMouseY()) / static_cast<double> (shape.GetPosition().x - input.GetMouseX()))));
}


This rotation code (any suggestions to improve it?) works just fine for sf::Sprite. But like I said, here it's messing up the whole thing.
When experimenting a bit with the values I passed to SetCenter() I noticed that the shape was seemingly displaced just about the parameters I passed to SetCenter().
What am I doing wrong?

Another little question:
When I am rotating the Shape, are the positions of the points added with AddPoint() influenced? Checking the points' coordinates made me think it wouldn't.