ARC_P() Unexpected results. - Printable Version

ARC_P() Unexpected results. - Printable Version

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ARC_P() Unexpected results. - matalog - 03-21-2022 10:57 PM

The following is drawing arcs using ARC_P(), and it works as expected most of the way, but at these values it displays an unexpected ARC. The same code works fine on ARCs over radius 15, but at a radius of 10, it jumps to this semicircle. You can see it in the video.

[Image: ARCw1.jpg?raw=1]

https://www.dropbox.com/s/s2moqdne4nryjlx/clip0227.avi?dl=0

Code:

EXPORT ANIM()

BEGIN

DIMGROB_P(G1,320,240);

 RECT_P();

 LOCAL A:=60;

LOCAL B:=2*π/A;

  WHILE ISKEYDOWN(4)=0 DO

LOCAL COL:=RANDINT(16777216);

LOCAL SIZE:=RANDINT(100);

  FOR N FROM 1 TO 60 DO

RECT_P(G1);

 ARC_P(G1,160,120,10,B*N/2-0.0001,2*π-B*N/2,{#000000h,COL}); 

  BLIT_P(G0,0,0,320,240,G1,0,0,320,240); 

  TEXTOUT_P(STRING(B*N/2-0.0001)+"  ,  "+STRING(2*π-B*N/2),100,20);

   WAIT(.1)

END;

    WAIT(.2) ;

FOR N FROM 1 TO 60 DO

RECT_P(G1);

 ARC_P(G1,160,120,10,B*(30-N/2),2*π-B*(30-N/2),{#000000h,COL}); 

  BLIT_P(G0,0,0,320,240,G1,0,0,320,240); 

  TEXTOUT_P(STRING(B*(30-N/2))+"  ,  "+STRING(2*π-B*(30-N/2)),100,20);

    WAIT(.1)

END;

    WAIT(.2)

END;

END;

Is it a problem with ARC_P? Or is it a problem with the approximation of the equations involving PI?

If I did not add the: -0.0001 in the first ARC_P() command, then the ARCs would also show similar problems with bigger radiuses.

waka waka.

RE: ARC_P() Unexpected results. - tgallo - 03-23-2022 10:48 AM

Does it behave the same way in both the virtual and actual calculators?

RE: ARC_P() Unexpected results. - matalog - 03-23-2022 11:21 AM

(03-23-2022 10:48 AM)tgallo Wrote: Does it behave the same way in both the virtual and actual calculators?

Yeah, it happens on both.