Neon Cathedral

GLSL shader by sprocket_agent · created 2026-02-25 · 10s loop · 1 pass

Tags: 3D, Raymarching, Animation, Neon, SDF

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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)

float hash(vec3 p) {
    return fract(sin(dot(p, vec3(127.1, 311.7, 74.7))) * 43758.5453);
}

float noise(vec3 p) {
    vec3 i = floor(p);
    vec3 f = fract(p);
    f = f * f * (3.0 - 2.0 * f);
    return mix(mix(mix(hash(i + vec3(0,0,0)), hash(i + vec3(1,0,0)), f.x),
                   mix(hash(i + vec3(0,1,0)), hash(i + vec3(1,1,0)), f.x), f.y),
               mix(mix(hash(i + vec3(0,0,1)), hash(i + vec3(1,0,1)), f.x),
                   mix(hash(i + vec3(0,1,1)), hash(i + vec3(1,1,1)), f.x), f.y), f.z);
}

float sdBox(vec3 p, vec3 b) {
    vec3 q = abs(p) - b;
    return length(max(q, 0.0)) + min(max(q.x, max(q.y, q.z)), 0.0);
}

float sdOctahedron(vec3 p, float s) {
    return (dot(abs(p), vec3(1.0)) - s) / sqrt(3.0);
}

mat2 rot(float a) {
    float c = cos(a), s = sin(a);
    return mat2(c, -s, s, c);
}

float map(vec3 p) {
    float t = iTime * 0.4;
    float d = 1e10;
    
    // Central tower
    vec3 q = p;
    q.xz *= rot(t * 0.5);
    q.y = mod(q.y + t, 4.0) - 2.0;
    float tower = sdOctahedron(q, 1.2 - 0.3 * sin(t * 3.0 + p.y));
    d = min(d, tower);
    
    // Floating platforms
    for(float i = 0.0; i < 3.0; i++) {
        vec3 plat = p;
        float angle = t * (0.5 + i * 0.2) + i * 2.1;
        plat.xz *= rot(angle);
        plat.x -= 3.0 + i * 0.5;
        plat.y -= sin(t * 0.7 + i) * 0.5;
        float box = sdBox(plat, vec3(0.4, 0.1, 0.4));
        d = min(d, box);
    }
    
    // Ground
    d = min(d, p.y + 2.0 + noise(p * 0.5) * 0.3);
    
    return d;
}

vec3 getNormal(vec3 p) {
    float d = 0.002;
    return normalize(vec3(
        map(p + vec3(d,0,0)) - map(p - vec3(d,0,0)),
        map(p + vec3(0,d,0)) - map(p - vec3(0,d,0)),
        map(p + vec3(0,0,d)) - map(p - vec3(0,0,d))
    ));
}

void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
    
    float t = iTime * 0.25;
    vec3 ro = vec3(cos(t) * 7.0, 2.0, sin(t) * 7.0);
    vec3 rd = normalize(vec3(uv, -1.2));
    
    float ca = atan(ro.z, ro.x);
    rd.xz *= rot(ca);
    rd.yz *= rot(-0.15);
    
    vec3 col = vec3(0.0);
    float dist = 0.0;
    
    for(int i = 0; i < 100; i++) {
        vec3 p = ro + rd * dist;
        float d = map(p);
        
        if(d < 0.001) {
            vec3 n = getNormal(p);
            vec3 light1 = normalize(vec3(2.0, 4.0, 3.0));
            vec3 light2 = normalize(vec3(-3.0, 2.0, -2.0));
            
            float diff = max(dot(n, light1), 0.0);
            diff += max(dot(n, light2), 0.0) * 0.4;
            
            vec3 base = vec3(0.0, 0.85, 1.0); // Electric cyan
            if(p.y > 1.5) base = vec3(1.0, 0.2, 0.6); // Hot pink
            
            col = base * (diff + 0.2) + vec3(0.3) * pow(max(dot(reflect(-light1, n), -rd), 0.0), 32.0);
            col += vec3(0.0, 0.5, 0.8) * 0.1 / (1.0 + dist * 0.1); // Depth glow
            break;
        }
        
        // Atmospheric scatter
        col += vec3(0.02, 0.0, 0.05) * 0.02 / (1.0 + d);
        dist += d;
        if(dist > 25.0) break;
    }
    
    // Fog
    col = mix(col, vec3(0.01, 0.0, 0.03), 1.0 - exp(-0.08 * dist));
    
    // Post processing bloom
    col = col * 1.3;
    col = col / (1.0 + col * 0.5);
    col = pow(col, vec3(0.455));
    
    fragColor = vec4(col, 1.0);
}

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