full Circle with cos sin and set(x,y,c)

Programming Questions

stanlepunk

full Circle with cos sin and set(x,y,c)

in Programming Questions • 7 months ago

Hello all,

I want draw a circle with this method, but I've a lot of hole in my disc, if anybody have an idea to make a real full disc, I take it.

color c = color(255) ;
//diameter of circle
int diam = 200 ;

void setup()
{
background(0) ;
size( 300,300 ) ;
   colorMode(HSB, 360, 100, 100 ) ;
fill(255) ;
}

void draw()
{
background(0) ;
PVector pos = new PVector( mouseX, mouseY ) ;
//make cirlce
//circle(pos, diam) ;
//make a disc

   disc(pos, diam) ;
//chromaticCircle(pos, diam) ;
//chromaticDisc(pos, diam) ;
}

//DISC
void disc( PVector pos, int diam )
{
for ( int i = 1 ; i < diam +1 ; i++) {
    circle(pos, i) ;
}
}
//CIRCLE
//classic
void circle(PVector pos, int d)
{
int surface = d*d ; // surface is equale of square surface where is the circle.

int radius = ceil(radiusSurface(surface)) ;
int numPoints = ceil(perimeterCircle( radius)) ;
for(int i=0; i < numPoints; i++) {
      float stepAngle = map(i, 0, numPoints, 0, 2*PI) ;
      float angle = 2*PI - stepAngle;
      set(int(pointOnCirlcle(pos, radius, angle).x + pos.x) , int(pointOnCirlcle(pos, radius, angle).y + pos.y), c);
}
}

//POINT
PVector pointOnCirlcle(PVector pos, int r, float angle)
{
PVector posPix = new PVector () ;
posPix.x = cos(angle) *r ;
posPix.y = sin(angle) *r ;

return posPix ;
}
//EQUATION
float perimeterCircle ( int r )
{
//calcul du perimetre
float p = 2*r*PI ;
return p ;

}

//EQUATION
float radiusSurface(int s)
{
// calcul du rayon par rapport au nombre de point
float r = sqrt(s/PI) ;
return r ;
}

Replies(3)

asimes

Re: full Circle with cos sin and set(x,y,c)

7 months ago

This gets rid of most of them, but there still must be rounding errors somewhere. I got rid of most of the holes just by using floats instead of ints. You can experiment and see which need to be floats and which you can get away with leaving as ints:

float diam = 200.0;
void setup() {
size(600, 600);
}
void draw() {
background(0);
PVector pos = new PVector(mouseX, mouseY);
for (int i = 1; i < diam+1; i++) circle(pos, i);
}
void circle(PVector pos, float d) {
float surface = d*d;
float radius = radiusSurface(surface);
float numPoints = perimeterCircle(radius);
for (int i = 0; i < numPoints; i++) {
float stepAngle = map(i, 0.0, numPoints, 0.0, TWO_PI);
float angle = TWO_PI-stepAngle;
set(int(pointOnCircle(pos, radius, angle).x+pos.x),
int(pointOnCircle(pos, radius, angle).y+pos.y), 0xffffffff);
}
}
PVector pointOnCircle(PVector pos, float r, float angle) {
PVector posPix = new PVector();
posPix.x = cos(angle)*r;
posPix.y = sin(angle)*r;
return posPix;
}
float perimeterCircle(float r) {
float p = TWO_PI*r;
return p;
}
float radiusSurface(float s) {
float r = sqrt(s/PI);
return r;
}

amnon.owed

Re: full Circle with cos sin and set(x,y,c)

7 months ago

I realise I'm not answering the question here, but in case the underlying reason for it was because you wanted to color pixels within a circle individually then check out the code below.

Code Example

color black = color(0);
int d = 50, diam = 100;
void setup() {
size(300, 300);
colorMode(HSB, 360, 100, 100);
}
void draw() {
background(black);
if (mousePressed) { d++; } else if (d>1) { d--; }
loadPixels();
for (int y=0; y<height; y+=d) {
for (int x=0; x<width; x+=d) {
if (dist(x, y, mouseX, mouseY) < diam) {
pixels[x+y*width] = color((x+y+frameCount)%360,100, 100);
} else {
pixels[x+y*width] = black;
}
}
}
updatePixels();
}

stanlepunk

Re: full Circle with cos sin and set(x,y,c)

7 months ago

Thx Asimes for your answer, like you say it's very close of the perfect disc, I try now to work on this way to remove the last holes.
Thx Amno for your moving circle Specter, I search on this way too, to make a perfect disc, and your code give few ideas. Your code is very light for the CPU, with mine the ressources of processor is 90-99% and your just 15%.

I post the final work here if I found the perfect code !

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