Fractal_01.osl

// Based on a method found by Kali on fractal forums, adapted and modded in GLSL, ported to OSL
// OSL version by Mads Drøschler
// 5.6.2018
// License CC3.0 

float fract ( float x )
{
	return x - floor (x);
}

float field(vector p,float s, float Time)
{
	float strength = 7. + .03 * log(1.e-6 + fract(sin(Time) * 4373.11));
	float accum = s/4.;
	float prev = 0.;
	float tw = 0.;
	for (int i = 0; i < 26; ++i)
{
		float mag = dot(p, p);
		p = abs(p) / mag + vector(-.5, -.4, -1.5);
		float w = exp(-float(i) / 7.);
		accum += w * exp(-strength * pow(abs(mag - prev), 2.2));
		tw += w;
		prev = mag;
}
	return max(0., 5. * accum / tw - .7);
}

float map2( vector p, float Time )
{
    float t = field(p,.5, Time);
    
    return t;
}

vector raymarch(vector ro, vector rd, vector tminmax, float Time )
{
    float t = tminmax[0];
    float dt = .2 * sin(Time*.1);
    vector col= vector(0.);
    float c = 0.;
    for( int i=0; i<10; i++ )
{
        t+=dt*exp(-2.*c);
        if(t>tminmax[1])break;
        c = map2(ro+t*rd, Time);               
        col = .99*col+ .08*vector(c*c*c, c*c, c);
}    
    return col;
}

vector render( vector ro, vector rd, float Time )
{
	float mindist = 1.0;
	float maxdist = 4.0;
    return raymarch(ro, rd, vector(mindist, maxdist,0),Time);
}

shader Fractal_01
(

 	point Po = P,
 	float Time = 0,
    output  vector Out = 0,
)
{
	vector uv = Po;
	Out = vector(uv[0],uv[1],0.5+0.5*sin(Time)); 
    vector  p = (-Po);
    float an = 1.87 - 0.04*(1.0-cos(0.5*Time));
    vector  ro = vector(-0.4,0.2,0.0) + 2.2*vector(cos(an),0.0,sin(an));
    vector  ta = vector(-0.6,0.2,0.);
    vector  rd = normalize( vector(p[0],p[1],-2.8) );
    vector col = render( ro, rd, Time );
    Out = vector( col);
}