// fitting polynomials to matplotlib colormaps by mattz
//
// License CC0 (public domain)
//   https://creativecommons.org/share-your-work/public-domain/cc0/
//
// feel free to use these in your own work!
//
// similar to https://www.shadertoy.com/view/XtGGzG but with a couple small differences:
//
//  - use degree 6 instead of degree 5 polynomials
//  - use nested horner representation for polynomials
//  - polynomials were fitted to minimize maximum error (as opposed to least squares)
//
// data fitted from https://github.com/BIDS/colormap/blob/master/colormaps.py
// (which is licensed CC0)

uniform int use_colormap; /// set:2 min:0 max:4 tip:"0:off,1:inferno,2:viridis,3:plasma,4:magma"

vec3 inferno_color_map(float t) {
    const vec3 c0 = vec3(0.0002189403691192265, 0.001651004631001012, -0.01948089843709184);
    const vec3 c1 = vec3(0.1065134194856116, 0.5639564367884091, 3.932712388889277);
    const vec3 c2 = vec3(11.60249308247187, -3.972853965665698, -15.9423941062914);
    const vec3 c3 = vec3(-41.70399613139459, 17.43639888205313, 44.35414519872813);
    const vec3 c4 = vec3(77.162935699427, -33.40235894210092, -81.80730925738993);
    const vec3 c5 = vec3(-71.31942824499214, 32.62606426397723, 73.20951985803202);
    const vec3 c6 = vec3(25.13112622477341, -12.24266895238567, -23.07032500287172);

    return c0+t*(c1+t*(c2+t*(c3+t*(c4+t*(c5+t*c6)))));
}

vec3 viridis_color_map(float t) {
    const vec3 c0 = vec3(0.2777273272234177, 0.005407344544966578, 0.3340998053353061);
    const vec3 c1 = vec3(0.1050930431085774, 1.404613529898575, 1.384590162594685);
    const vec3 c2 = vec3(-0.3308618287255563, 0.214847559468213, 0.09509516302823659);
    const vec3 c3 = vec3(-4.634230498983486, -5.799100973351585, -19.33244095627987);
    const vec3 c4 = vec3(6.228269936347081, 14.17993336680509, 56.69055260068105);
    const vec3 c5 = vec3(4.776384997670288, -13.74514537774601, -65.35303263337234);
    const vec3 c6 = vec3(-5.435455855934631, 4.645852612178535, 26.3124352495832);

    return c0+t*(c1+t*(c2+t*(c3+t*(c4+t*(c5+t*c6)))));
}

vec3 plasma_color_map(float t) {
    const vec3 c0 = vec3(0.05873234392399702, 0.02333670892565664, 0.5433401826748754);
    const vec3 c1 = vec3(2.176514634195958, 0.2383834171260182, 0.7539604599784036);
    const vec3 c2 = vec3(-2.689460476458034, -7.455851135738909, 3.110799939717086);
    const vec3 c3 = vec3(6.130348345893603, 42.3461881477227, -28.51885465332158);
    const vec3 c4 = vec3(-11.10743619062271, -82.66631109428045, 60.13984767418263);
    const vec3 c5 = vec3(10.02306557647065, 71.41361770095349, -54.07218655560067);
    const vec3 c6 = vec3(-3.658713842777788, -22.93153465461149, 18.19190778539828);

    return c0+t*(c1+t*(c2+t*(c3+t*(c4+t*(c5+t*c6)))));
}

vec3 magma_color_map(float t) {
    const vec3 c0 = vec3(-0.002136485053939582, -0.000749655052795221, -0.005386127855323933);
    const vec3 c1 = vec3(0.2516605407371642, 0.6775232436837668, 2.494026599312351);
    const vec3 c2 = vec3(8.353717279216625, -3.577719514958484, 0.3144679030132573);
    const vec3 c3 = vec3(-27.66873308576866, 14.26473078096533, -13.64921318813922);
    const vec3 c4 = vec3(52.17613981234068, -27.94360607168351, 12.94416944238394);
    const vec3 c5 = vec3(-50.76852536473588, 29.04658282127291, 4.23415299384598);
    const vec3 c6 = vec3(18.65570506591883, -11.48977351997711, -5.601961508734096);

    return c0+t*(c1+t*(c2+t*(c3+t*(c4+t*(c5+t*c6)))));
}

void mainImage( out vec4 fragColor, in vec2 fragCoord ) {
    vec2 uv = fragCoord.xy / iResolution.xy;
    vec4 src = texture(iChannel0, uv);

    if(use_colormap == 0) { fragColor = src; return; }

    float luma = dot(src.rgb, vec3(0.299, 0.587, 0.114));
    if(use_colormap == 1) { fragColor = vec4(inferno_color_map(luma), src.a); return; }
    if(use_colormap == 2) { fragColor = vec4(viridis_color_map(luma), src.a); return; }
    if(use_colormap == 3) { fragColor = vec4(plasma_color_map(luma), src.a); return; }
    if(use_colormap == 4) { fragColor = vec4(magma_color_map(luma), src.a); return; }
}