plot.shadron

#define PLOT_SAMPLES 3

template <FN, XMIN, XMAX, YMIN, YMAX, XGRID, YGRID>
glsl vec4 plot(vec2 pos) {
    vec2 tPos = vec2(
        mix(float(XMIN), float(XMAX), pos.x),
        mix(float(YMIN), float(YMAX), pos.y)
    );
    vec2 pxSize = vec2((XMAX)-(XMIN), (YMAX)-(YMIN))*shadron_PixelSize;

    float opacity = 0.0;
    for (int ys = 0; ys < PLOT_SAMPLES; ++ys)
        for (int xs = 0; xs < PLOT_SAMPLES; ++xs) {
            vec2 stPos = tPos+pxSize*vec2(float(2*xs-(PLOT_SAMPLES-1)), float(2*ys-(PLOT_SAMPLES-1)))*(1.0/float(2*PLOT_SAMPLES));
            float y = FN(stPos.x);
            float high = y;
            float low = y;
            for (int i = 1; i <= 4; ++i) {
                float ny = FN(stPos.x+0.25*pxSize.x*float(i));
                low = min(low, ny);
                high = max(high, ny);
                ny = FN(stPos.x-0.25*pxSize.x*float(i));
                low = min(low, ny);
                high = max(high, ny);
            }
            opacity += float(stPos.y >= low-pxSize.y && stPos.y <= high+pxSize.y);
        }
    
    opacity *= 1.0/float(PLOT_SAMPLES*PLOT_SAMPLES);

    vec2 grid = 0.5-abs(0.5-mod(tPos/vec2(XGRID, YGRID), vec2(1.0)));
    if (abs(tPos.x) < pxSize.x || abs(tPos.y) < pxSize.y)
        opacity += 0.5;
    else if (grid.x*(XGRID) <= 0.5*pxSize.x || grid.y*(YGRID) <= 0.5*pxSize.y)
        opacity += 0.25;
    return vec4(0.0, 0.0, 0.0, opacity);
}