// Lissajous — four curves x = sin(a s + phi), y = sin(b s) traced like a phosphor
// scope: 48 samples trail behind a moving head, the distance to each segment adds
// glow, and the weight fades toward the tail so the trace has persistence.
float segmentDist(vec2 p, vec2 a, vec2 b) {
vec2 pa = p - a;
vec2 ba = b - a;
float h = clamp(dot(pa, ba) / max(dot(ba, ba), 1e-6), 0.0, 1.0);
return length(pa - ba * h);
}
// k = (a, b, phi, amplitude)
vec2 curvePoint(float s, vec4 k) {
return k.w * vec2(1.45 * sin(k.x * s + k.z), 0.85 * sin(k.y * s));
}
float trace(vec2 p, vec4 k, float head, float span, float pixel) {
float glow = 0.0;
vec2 prev = curvePoint(head, k);
for (int i = 1; i <= 48; i++) {
float f = float(i) / 48.0;
vec2 next = curvePoint(head - f * span, k);
float d = segmentDist(p, prev, next);
float weight = (1.0 - f) * (1.0 - f);
glow += weight * (smoothstep(pixel * 2.0, 0.0, d) + 0.5 * 0.0015 / (d * d + 0.0015));
prev = next;
}
vec2 headPoint = curvePoint(head, k);
glow += 0.004 / (dot(p - headPoint, p - headPoint) + 0.004);
return glow;
}
void mainImage(out vec4 fragColor, in vec2 fragCoord) {
vec2 p = (fragCoord - 0.5 * iResolution.xy) / iResolution.y * 2.2;
float pixel = 2.2 / iResolution.y;
float t = iTime * 0.45;
float traceA = trace(p, vec4(3.0, 2.0, 1.5708, 1.0), t, 1.3, pixel);
float traceB = trace(p, vec4(1.0, 3.0, 0.7854, 0.8), t * 0.85 + 2.0, 2.2, pixel);
float traceC = trace(p, vec4(5.0, 4.0, 0.0, 0.92), t * 0.6 + 4.0, 0.8, pixel);
float traceD = trace(p, vec4(2.0, 3.0, 0.5, 0.6), t * 0.7 + 1.0, 3.0, pixel);
vec3 col = vec3(0.03, 0.015, 0.02);
col += vec3(0.70, 0.15, 0.12) * traceA * 0.9;
col += vec3(0.94, 0.41, 0.36) * traceB * 0.8;
col += vec3(0.94, 0.41, 0.36) * traceC * 0.45;
col += vec3(0.70, 0.15, 0.12) * traceD * 0.7;
col += vec3(1.0, 0.9, 0.85) * (traceA + traceB + traceC + traceD) * 0.12;
col = col / (1.0 + col);
fragColor = vec4(pow(col, vec3(0.9)), 1.0);
}
A tracker module is the score, not the recording: a handful of short samples and a grid of notes, small enough for a floppy disk, performed live by the machine. The Amiga and PC demoscenes shipped music this way for a decade before MP3. These 40 pieces run from 1987 to 2025 and play here the same way: libopenmpt, compiled to WebAssembly, performs every row in your browser while the pattern scrolls past.
Drag or scroll the reel to travel through the years and pick a frame to load it. Random shader opens one of the shaders fullscreen while the music keeps playing. Each piece is the work of its composer; the files stream from The Mod Archive when you press play, and none are hosted here.
1993 · The PC catches up
Purple Motion (Jonne Valtonen) · Future Crew
Purple Motion’s part of the Second Reality soundtrack (1st place, PC demo competition, Assembly 1993)
Purple Motion’s part of the soundtrack to Future Crew’s Second Reality, which won the PC demo competition at Assembly 1993. It is first on all three Mod Archive charts, most downloaded, most revered, and most favourited, which is why the reel opens here.
S3M
This module on The Mod Archive
Exhibit 17 of 40
0:00 / 0:00
Nothing downloads until you press play.
Song order
The scrolling pattern and level meters are off because your system asks for reduced motion.