# Les shader's de Lulu

Aspirage de boules fantomatique

float length2( vec2 p )
{
	return sqrt( p.x*p.x + p.y*p.y );
}

float length4( vec2 p )
{
	p = p*p; p = p*p;
	return pow( p.x + p.y, 1.0/4.0 );
}

float length6( vec2 p )
{
	p = p*p*p; p = p*p;
	return pow( p.x + p.y, 1.0/6.0 );
}

float length8( vec2 p )
{
	p = p*p; p = p*p; p = p*p;
	return pow( p.x + p.y, 1.0/0.4 );
}

float length8( vec3 p )
{
	p = p*p; p = p*p; p = p*p;
	return pow( p.x + p.y + p.z, 1.0/8.0 );
}




//-------------------------------------------------

float sdCappedCylinder( vec3 p, vec2 h )
{
  vec2 d = abs(vec2(length(p.xz),p.y)) - h;
  return min(max(d.x,d.y),0.0) + length(max(d,0.0));
}

float sdCappedCylinder4( vec3 p, vec2 h )
{
  vec2 d = abs(vec2(length4(p.xz),p.y)) - h;
  return min(max(d.x,d.y),0.0) + length4(max(d,0.0));
}


float sdTorus( vec3 p, vec2 t )
{
  vec2 q = vec2(length(p.xz)-t.x,p.y);
  return length(q)-t.y;
}

float sdTorus82( vec3 p, vec2 t )
{
  vec2 q = vec2(length8(p.xz)-t.x,p.y);
  return length2(q)-t.y;
}


float sdSphere( in vec3 p, in float r )
{
    return length(p)-r;
}

float sdSphere8( in vec3 p, in float r )
{
    return length8(p)-r;
}

//---------------------------------

float map(in vec3 pos)
{
    float d = 1e10;
    float popox = (iMouse.x / iResolution.x * 2.) - 1.5;
    float popoy = (iMouse.y / iResolution.y * 2.) - 0.5;
    

    // double onion sphere
    {
    vec3 q = pos - vec3(popox,popoy,tan(popox * popoy));
    d = min( d, sdSphere8( q, 0.4 ) );
    }

     
    // single onion cylinder
    {
    vec3 q = pos - vec3(popox,popoy,tan(popox * popoy));
    d = min( d, sdCappedCylinder4( q, vec2(4.4,0.2) ) );
    }

   
    
    // single onion torus
    {
    vec3 q = pos - vec3(popox,popoy,tan(popox * popoy));
    d = min( d, sdTorus82( q, vec2(0.4,4.1) ) );
    }

    // torus
    {
    vec3 q = pos - vec3(popox,popoy,tan(popox * popoy));
    d = min( d, sdTorus( q.xzy, vec2(0.5,0.2) ) );
    }
 
    return d;
}

// http://iquilezles.org/www/articles/normalsSDF/normalsSDF.htm
vec3 calcNormal( in vec3 pos )
{
    const float ep = 0.0001;
    vec2 e = vec2(1.0,-1.0)*0.5773;
    return normalize( e.xyy*map( pos + e.xyy*ep ) + 
					  e.yyx*map( pos + e.yyx*ep ) -
					  e.yxy*map( pos + e.yxy*ep ) +
					  e.xxx*map( pos + e.xxx*ep ) );
}

#define AA 3

void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
   vec3 tot = vec3(0.0);
    
    #if AA>1
    for( int m=0; m<AA; m++ )
    for( int n=0; n<AA; n++ )
    {
        // pixel coordinates
        vec2 o = vec2(float(m),float(n)) / float(AA) - 0.5;
        vec2 p = (-iResolution.xy + 2.0*(fragCoord+o))/iResolution.y;
        #else    
        vec2 p = (-iResolution.xy + 2.0*fragCoord)/iResolution.y;
        #endif
 
        vec3 ro = vec3(0.0,3.0,6.0);
        vec3 rd = normalize(vec3(p-vec2(0.0,1.0),-2.0));

        float t = 5.0;
        for( int i=0; i<80; i++ )
        {
            vec3 p = ro + t*rd;
            float h = map(p);
            if( abs(h)<0.001 || t>10.0 ) break;
            t += h;
        }

        vec3 col = vec3(0.0);

        if( t<10.0 )
        {
            vec3 pos = ro + t*rd;
            vec3 nor = calcNormal(pos);
            vec3  lig = normalize(vec3(1.0,0.8,-0.2));
            float dif = clamp(dot(nor,lig),0.0,1.0);
            float amb = 0.5 + 0.5*nor.y;
            col = vec3(0.05,0.1,0.15)*amb + 
                  vec3(1.00,0.9,0.80)*dif;
        }

        col = sqrt( col );
	    tot += col;
    #if AA>1
    }
    tot /= float(AA*AA);
    #endif

	fragColor = vec4( tot, 1.0 );
}