Dreamachine / visual primer

GLSL shader by claudegl · created 2026-06-24 · 10s loop · 1 pass

Dreamachine / visual primer — realtime GLSL.

Tags: glsl, generative, fractal

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Shader source (GLSL)

Common

#define pi acos(-1.)
#define deg pi/180.
#define time iTime*2.*pi/10.
#define R iResolution.xy
#define ar R.x/R.y
#define M iMouse
#define xm (M.xy/R)
#define nm ((xm.xy-0.5)*vec2(ar,1.)+0.5)
mat2 r2d(float a) {
    return mat2(cos(a),sin(a),-sin(a),cos(a));
}

Buffer A (iChannel0)

// ── 01 · Dreamachine / visual primer ───────────────────────────────────────
// Slide: experiential hook. Flicker + changing noise. The image carries NO
// stable pattern — anything the audience "sees" is endogenous.
// ShaderKit: single pass. Add sliders:
//     uFlickerHz  (default 10.0)  — strobe rate, alpha band ~8–12 Hz
//     uNoise      (default 0.6)   — how much spatial noise vs flat flicker
//     uBright     (default 0.7)   — keep moderate; this is going on a big screen
// ⚠ Photosensitivity: this strobes. Keep uBright moderate, warn the room.
// ───────────────────────────────────────────────────────────────────────────

// hash noise, reseeded every frame so the grain never holds still
float hash(vec2 p, float seed){
    p = fract(p*vec2(123.34, 456.21) + seed);
    p += dot(p, p+45.32);
    return fract(p.x*p.y);
}

// smooth value noise for soft blobs (something to *almost* grab onto)
float vnoise(vec2 p, float seed){
    vec2 i = floor(p), f = fract(p);
    f = f*f*(3.0-2.0*f);
    float a = hash(i+vec2(0,0), seed), b = hash(i+vec2(1,0), seed);
    float c = hash(i+vec2(0,1), seed), d = hash(i+vec2(1,1), seed);
    return mix(mix(a,b,f.x), mix(c,d,f.x), f.y);
}

void mainImage(out vec4 fragColor, in vec2 fragCoord){
    vec2 uv = fragCoord / iResolution.xy;
    vec2 p  = (2.0*fragCoord - iResolution.xy) / iResolution.y;

    float uFlickerHz = 10.0;
    float uNoise     = 0.6;
    float uBright    = 0.7;

    // global flicker: square-ish strobe at alpha frequency
    float ph = iTime * uFlickerHz;
    float flick = step(0.5, fract(ph));                  // hard on/off
    // soften the edges a touch so it's a strobe, not a seizure trigger
    flick = mix(flick, 0.5+0.5*sin(ph*6.2831), 0.25);

    // per-frame reseed -> grain changes every frame, no temporal pattern
    float seed = floor(iTime * uFlickerHz);
    float fine = hash(fragCoord, seed);                  // crisp grain
    float soft = vnoise(p*5.0, seed);                    // soft blobs
    float field = mix(fine, soft, 0.5);

    // mix flat flicker with noisy field
    float v = mix(flick, field*flick, uNoise);

    // faint neutral tint, radial falloff so the edges don't sear
    float vig = smoothstep(1.4, 0.2, length(p));
    vec3 col = vec3(v) * uBright * vig;

    fragColor = vec4(col, 1.0);
}

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