2d folding

fold_2d.glsl

#version 150

in VertexData
{
    vec4 v_position;
    vec3 v_normal;
    vec2 v_texcoord;
} inData;

out vec4 fragColor;

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uniform vec2 iResolution;
uniform float iTime;
uniform float iTimeDelta;
uniform int iFrame;
uniform vec4 iMouse;
uniform sampler2D iChannel0;
uniform sampler2D iChannel1;
uniform sampler2D iChannel2;
uniform sampler2D iChannel3;
uniform vec4 iDate;
uniform float iSampleRate;

void mainImage(out vec4, in vec2);
void main(void) { mainImage(fragColor,inData.v_texcoord * iResolution.xy); }

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const float Size = 7;
const float Scale = 2;
const vec3 plnormal = normalize(vec3(1, 1, -1));

#define Phi (.5*(1.+sqrt(5.)))
const vec3 n1 = normalize(vec3(-Phi,Phi-1.0,1.0));
const vec3 n2 = normalize(vec3(1.0,-Phi,Phi+1.0));
const vec3 n3 = normalize(vec3(0.0,0.0,-1.0));

float de(in vec3 z)
{
        float t;
        // Folds.
        //Dodecahedral.. you can use other sets of foldings!
        z = abs(z);
        t=dot(z,n1); if (t>0.0) { z-=2.0*t*n1; }
        t=dot(z,n2); if (t>0.0) { z-=2.0*t*n2; }
        z = abs(z);
        t=dot(z,n1); if (t>0.0) { z-=2.0*t*n1; }
        t=dot(z,n2); if (t>0.0) { z-=2.0*t*n2; }
        z = abs(z);

        //combine DEs... explore different combinations ;)
        //the base DE is the distance to the plane going through vec3(Size,0.,0.) and which normal is plnormal
        float dmin=dot(z-vec3(Size,0.,0.),plnormal);
        
        // Rotate, scale, rotate (we need to cast to a 4-component vector).
    return (dmin);//you can take a look to the inside
}



void mainImage(out vec4 fragColor, in vec2 fragCoord)
{
    vec2 uv = fragCoord.xy / iResolution.xy;
    uv = 2.0*(uv - 0.5);
    uv.x *= iResolution.x/iResolution.y;
    
    float d = de(vec3(uv*7, 7.0*sin(0)));
    
    vec3 col = abs(d) < 0.01 ? vec3(1.0) : vec3(0.0);
    
    fragColor = vec4(col,1.0);
}