Book of Shaders

mondrian.c

// Author @patriciogv - 2015
// http://patriciogonzalezvivo.com

#ifdef GL_ES
precision mediump float;
#endif

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

/* -- */
float gap(float left,  float right, float v){
    return step(0.0, v) - step(left, v) + step(right, v);
}

float gap(vec2 left, vec2 right, vec2 v){
    vec2 res = step(vec2(0.0), v) - step(left, v) + step(right, v);
    return res.x + res.y;
}

void main(){
    vec2 st = gl_FragCoord.xy/u_resolution.xy;
    vec3 color = vec3(0.0);

    float pct   = 0.0;
    // full horiontal lines
    pct = gap(0.8,0.84, st.y);
    pct *= gap(0.6,0.64, st.y);
    // full vertical lines
    pct *= gap(0.2,0.24, st.x);
    pct *= gap(0.66,0.7, st.x);
    pct *= gap(0.9,0.94, st.x);
    
    // partial lines
    pct *= gap(vec2(0.1, 0.6), vec2(0.14,1.0), st);
    pct *= gap(vec2(0.2, 0.2), vec2(1.0,0.24), st);
    color = vec3(pct);

    gl_FragColor = vec4(color,1.0);
}

pow.c

// Author: Inigo Quiles
// Title: Expo
// Modified: Serser

#ifdef GL_ES
precision mediump float;
#endif

#define PI 3.14159265359

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

float pow5(float y) {
    return pow(y, 5.0);
}
float plot(vec2 st, float pct, float barrier){
  return  smoothstep( pct-barrier, pct, st.y) - 
          smoothstep(pct, pct+barrier, st.y);
}

void main() {
    vec2 st = gl_FragCoord.xy/u_resolution;

    float y = pow(st.x,5.0);
    float bar = pow(st.x, 4.0) * 5.0; // tan theta
    bar = sqrt(1.0/(bar*bar +1.0));  //cos theta
    bar = 0.01/bar;
	//float y = st.x;
    vec3 color = vec3(y); 
   // bar = 0.02;
    float pct = plot(st,y, bar);
    color =(1.0-pct)*color+pct*vec3(0.0,1.0,0.0);
    
    gl_FragColor = vec4(color,1.0);
}

smoothstep.c

// https://thebookofshaders.com/glossary/?search=smoothstep

#ifdef GL_ES
precision mediump float;
#endif

#define PI 3.14159265359

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

float plot(vec2 st, float pct, float barrier){
  return  smoothstep( pct-barrier, pct, st.y) - 
          smoothstep( pct, pct+barrier, st.y);
}

float smoothstepderivative(float low, float high, float x){
    if (x>high || x <low) {
        return 0.;
    } 
    return 1.0/(high-low);
}

void main() {
    vec2 st = gl_FragCoord.xy/u_resolution;

    // Smooth interpolation between 0.1 and 0.9
    float y = smoothstep(0.1, 0.9, st.x);

    vec3 color = vec3(y);
    float bar = smoothstepderivative(0.1, 0.9, y);
    bar = 0.01/sqrt(1.0/(bar*bar +1.0)); //cos
    float pct = plot(st,y,bar);
    color = (1.0-pct)*color+pct*vec3(0.0,1.0,0.0);

    gl_FragColor = vec4(color,1.0);
}