[SOLVED] Rotate Rectangle Corners Around Origin Help
lazarus / 39-Graphics

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JasonLugg · 2018-04-10 14:52

Hi All and once again Thx in advance!

I have a function (grabbed from Stack Exchange
here:https://gamedev.stackexchange.com/questions/86755/how-to-
calculate-corner-positions-marks-of-a-rotated-tilted-rectangle) which
does pretty much what I wish. It rotates a point around an origin.

This is the function:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i Function
TForm1.CalcRotatedPosition(Rx: single; Ry: single; Ox: single;       
               Oy: single; Angle: single): TPoint;var 
 cosine:single;   sine:single;   TmpPoint: TPoint;   NewPoint:
TPoint;begin   cosine:=cos(Angle);   sine:=sin(Angle);    //Translate
back from origin   TmpPoint.x:=Round(Rx-Ox);   TmpPoint.y:=Round(Ry-
Oy);    //Rotate Point   NewPoint.x:=Round(TmpPoint.x * cosine -
TmpPoint.y * sine);   NewPoint.y:=Round(TmpPoint.x * sine + TmpPoint.y
* cosine);    //Translate Back To origin 
 TmpPoint.x:=Round(NewPoint.x + Ox);   TmpPoint.y:=Round(NewPoint.y +
Oy);    Result:=TmpPoint; end; 
If I use an angle below 1.0 the corners oscillate slightly in and out
(not wanted!).

However, at angle:=1.0 it rotates too fast (Using BGRAVirtualScreen).
I would like to slow it down but maybe my math is not good enough to
work out how!

I have tried hard coding a delay but this does not work (movement too
jerky).

What can I do?


[SOLUTION]
Do not Round, use singles works smoothly with Angle=0.02!