i dont see what the bug report has to do with your arc problem.
and what exactly is the problem with your arc again? dont see any. can you post a screenshot of what it looks like for you and describe where the problem occures cause when i run your code it looks like expected.

This is what i'm talking about:

can you add the whole code for that... would like to replicate it.

thx

2. void setup()
3. {
4.   size(640,480,P3D);
5.   
6. }
7. 
   
8. void draw()
9. {
10.   background(0);
11.   stroke(255,0,0);
12.   noFill();  
13. strokeWeight(28);  
14.   arc(200,200,100,100,0,PI);
15. }

ah alright i see.
Its due to the renderer, i dont think there is an easy way to solve it. if you really need a 3d renderer and cant switch to P2D or JAVA2D. maybe creating your own segment function based on shapes solves your problem.

something like that :



void setup()
{
  size(640,480,P3D);
 
}

void draw()
{
  background(0);
  stroke(255,0,0);
 fill(255,0,0);
 translate(width/2,height/2);
  segment(100,0,180,150);
}


void segment(int resolution,float start, float end, float radius){
  beginShape(QUAD_STRIP);
  for(int i=0;i<resolution;i++){
    float d=radians(map(i,0,resolution-1,start,end));

    vertex(sin(d)*radius,cos(d)*radius);
    vertex(sin(d)*radius*1.15,cos(d)*radius*1.15);
  }
  endShape();
}