// Author: Sol Sarratea @solquemal

// Title: Curva de Koch - 0

// Repaso sobre clase anterior

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#ifdef GL_ES

  precision mediump float;

#endif

​

uniform float u_time;

uniform vec2  u_resolution;

#define PI 3.1415926538

​

vec2 uv(){

   /* Devuelve las posiciones del canvas en rango [-1.,1.]x[-1.,1.] */

   vec2 pos = gl_FragCoord.xy/u_resolution; 

   pos = pos *2.-1.;

   return pos;

}

​

float sdBox( in vec2 p, in vec2 b ){

    vec2 d = abs(p)-b;

    return length(max(d,0.0)) + min(max(d.x,d.y),0.0);

}

​

vec2 rotate(vec2 pos,float a){

    return pos * mat2(cos(a),sin(a),-sin(a),cos(a));

}

​

​

void main () {

    vec2 pos = uv(); vec3 color;

​

    /////////////////////////////////////

    //Aplicamos transformaciones lineales

​

    pos.x = abs(pos.x);

    pos -= vec2(0.5,0.);

    pos *= 1.008;

​

    color.r = (1.-step(0.009,distance(pos.x,0.)))

        *float(pos.y > 0. && pos.y<0.53);

    color.b = (1.-step(0.009,distance(pos.y,0.)))

        *float(pos.x > 0. && pos.x<0.53);

    float box =  smoothstep(.0,.01,sdBox(pos, vec2(.3)));

    color += box;

    gl_FragColor = vec4(color,1.);

}

​

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​