sticker-sheet.glsl

float PI = 3.14;

vec3 hsv2rgb(vec3 c)
{
    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
}
float smin( float a, float b, float k )
{
    float h = clamp( 0.5+0.5*(b-a)/k, 0.0, 1.0 );
    return mix( b, a, h ) - k*h*(1.0-h);
}


// The following are from http://iquilezles.org/www/articles/distfunctions2d/distfunctions2d.htm:

float sdCircle( vec2 p, float r )
{
  return length(p) - r;
}

float sdBox( in vec2 p, in vec2 b )
{
    vec2 d = abs(p)-b;
    return length(max(d,vec2(0))) + min(max(d.x,d.y),0.0);
}

float sdEquilateralTriangle( in vec2 p )
{
    const float k = sqrt(3.0);
    
    p.x = abs(p.x) - 1.0;
    p.y = p.y + 1.0/k;
    if( p.x + k*p.y > 0.0 ) p = vec2( p.x - k*p.y, -k*p.x - p.y )/2.0;
    p.x -= clamp( p.x, -2.0, 0.0 );
    return -length(p)*sign(p.y);
}

float sdPentagon( in vec2 p, in float r )
{
    const vec3 k = vec3(0.809016994,0.587785252,0.726542528);
    p.x = abs(p.x);
    p -= 2.0*min(dot(vec2(-k.x,k.y),p),0.0)*vec2(-k.x,k.y);
    p -= 2.0*min(dot(vec2( k.x,k.y),p),0.0)*vec2( k.x,k.y);
    return length(p-vec2(clamp(p.x,-r*k.z,r*k.z),r))*sign(p.y-r);
}

float sdCross( in vec2 p, in vec2 b, float r ) 
{
    p = abs(p); p = (p.y>p.x) ? p.yx : p.xy;
    
    vec2  q = p - b;
    float k = max(q.y,q.x);
    vec2  w = (k>0.0) ? q : vec2(b.y-p.x,-k);
    return sign(k)*length(max(w,0.0)) + r;
}
// http://www.iquilezles.org/www/articles/palettes/palettes.htm
// As t runs from 0 to 1 (our normalized palette index or domain), 
//the cosine oscilates c times with a phase of d. 
//The result is scaled and biased by a and b to meet the desired constrast and brightness.
vec3 cosPalette( float t, vec3 a, vec3 b, vec3 c, vec3 d )
{
    return a + b*cos( 6.28318*(c*t+d) );
}

// The following are from http://mercury.sexy/hg_sdf/

// Rotate around a coordinate axis (i.e. in a plane perpendicular to that axis) by angle <a>.
// Read like this: R(p.xz, a) rotates "x towards z".
// This is fast if <a> is a compile-time constant and slower (but still practical) if not.
void pR(inout vec2 p, float a) {
    p = cos(a)*p + sin(a)*vec2(p.y, -p.x);
}

// Shortcut for 45-degrees rotation
void pR45(inout vec2 p) {
    p = (p + vec2(p.y, -p.x))*sqrt(0.5);
}

// Repeat space along one axis. Use like this to repeat along the x axis:
// <float cell = pMod1(p.x,5);> - using the return value is optional.
float pMod1(inout float p, float size) {
    float halfsize = size*0.5;
    float c = floor((p + halfsize)/size);
    p = mod(p + halfsize, size) - halfsize;
    return c;
}

// Same, but mirror every second cell so they match at the boundaries
float pModMirror1(inout float p, float size) {
    float halfsize = size*0.5;
    float c = floor((p + halfsize)/size);
    p = mod(p + halfsize,size) - halfsize;
    p *= mod(c, 2.0)*2 - 1;
    return c;
}

// Repeat the domain only in positive direction. Everything in the negative half-space is unchanged.
float pModSingle1(inout float p, float size) {
    float halfsize = size*0.5;
    float c = floor((p + halfsize)/size);
    if (p >= 0)
        p = mod(p + halfsize, size) - halfsize;
    return c;
}

// Repeat around the origin by a fixed angle.
// For easier use, num of repetitions is use to specify the angle.
float pModPolar(inout vec2 p, float repetitions) {
    float angle = 2*PI/repetitions;
    float a = atan(p.y, p.x) + angle/2.;
    float r = length(p);
    float c = floor(a/angle);
    a = mod(a,angle) - angle/2.;
    p = vec2(cos(a), sin(a))*r;
    // For an odd number of repetitions, fix cell index of the cell in -x direction
    // (cell index would be e.g. -5 and 5 in the two halves of the cell):
    if (abs(c) >= (repetitions/2)) c = abs(c);
    return c;
}

// Repeat in two dimensions
vec2 pMod2(inout vec2 p, vec2 size) {
    vec2 c = floor((p + size*0.5)/size);
    p = mod(p + size*0.5,size) - size*0.5;
    return c;
}


//// the following are from the book of shaders
///

float random (in vec2 _st) {
    return fract(sin(dot(_st.xy,
                         vec2(12.9898,78.233)))*
        43758.5453123);
}