Made a composition that uses a cikernel to draw a stroked circle (torus) with aspect ratio control.
//gtoledo 2013
float torus( const in vec2 p, const in float r1, const in float r2 ){
vec2 q = vec2(length(p.xy)-r1);
return length(q)-r2;
}
kernel vec4 points(__color ringColor, vec2 resolution, float majRadius, float minRadius, float aspectRatio,vec2 shift, float ringSize, float steps){
float epsilon=000001;
vec2 p = ((destCoord()/resolution.xy)- vec2( 0.5, 0.5 ))*(1./ringSize);
p.y /= aspectRatio;
float x=p.x-shift.x;
float y=p.y-shift.y;
float a= 1.-torus(vec2(x,y),majRadius,minRadius);
vec3 d=(vec3(a)/abs(steps+1.+epsilon));//dim
return vec4(vec3(d)*ringColor.rgb,1.0);
}
