Project_2026-01-23_16-19-46

GLSL shader by scry · created 2026-01-24 · 10s loop · 2 passes

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Shader source (GLSL)

Common

#define pi acos(-1.)
#define deg pi/180.  //1 degree
#define time iTime*2.*pi/10. //sin(time) loops 10 seconds
#define R iResolution.xy //shorthand
#define ar R.x/R.y //aspect ratio
#define M iMouse //shorthand
#define xm (M.xy/R) //normalized mouse
#define nm ((xm.xy-0.5)*vec2(ar,1.)+0.5) //aspect ratio correction
vec3 cs = vec3(1.,2.,3.);
mat2 r2d(float a) {
    return mat2(cos(a),sin(a),-sin(a),cos(a));
}

Buffer A (iChannel0)

// Quality settings - adjust these to reduce artifacts
#define MARCH_STEPS 428
#define MARCH_PRECISION 0.0001
#define MARCH_STEP_SCALE 0.6
#define NORMAL_EPSILON 0.005
#define REFRACT_STEPS 64
#define REFRACT_PRECISION 0.0001

float sabs(float x, float k) {
    return sqrt(x*x + k);
}

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 map(vec3 p) {
    p.xz *= r2d(time * 0.3);
    p.xy *= r2d(time * 0.2);
    for (int i=0;i<6;i++) {
        p = vec3(sabs(p.x, 0.004), sabs(p.y, 0.004), sabs(p.z, 0.004))
            - 0.2*(sin(vec3(1.,2.,3.)+float(i)*pi/2.+time)*0.5+0.5);
        p.xz *= r2d(deg*90.);
    }
    float d = sdBox(p, vec3(0.1));
    d = length(p)-0.1;
    return d;
}

vec3 getNormal(vec3 p) {
    vec2 e = vec2(NORMAL_EPSILON, 0.0);
    return normalize(vec3(
        map(p + e.xyy) - map(p - e.xyy),
        map(p + e.yxy) - map(p - e.yxy),
        map(p + e.yyx) - map(p - e.yyx)
    ));
}
vec3 c1(vec2 uv) {
    uv *= 10.;
    vec2 grid = fract(uv * 10.0);
    float checker = step(0.5, mod(floor(uv.x * 10.0) + floor(uv.y * 10.0), 2.0));
    return vec3(checker * 0.1 + 0.05);
}
vec3 background(vec3 rd) {
    vec2 uv = rd.xy / (rd.z + 1.0) * 0.5 + 0.5;
    vec3 gradient = mix(vec3(0.2, 0.4, 1.0), vec3(1.0, 0.9, 0.8), rd.y * 0.5 + 0.5);
    vec3 pattern = c1(uv);
    return mix(gradient, pattern, 0.3);
}



void mainImage(out vec4 fragColor, in vec2 fragCoord) {
    vec2 uv = fragCoord.xy / iResolution.xy;
    uv -= 0.5;
    uv.x *= ar;
    
    vec3 ro = vec3(0., 0., -2.);
    vec3 rd = normalize(vec3(uv, 1.0));
    
    vec3 col = background(rd);
    
    float t = 0.0;
    
    for(int i = 0; i < MARCH_STEPS; i++) {
        vec3 p = ro + rd * t;
        float d = map(p);
        if(d < MARCH_PRECISION) {
            vec3 n = getNormal(p);
            
            // Fresnel and refraction
            float ior = 1.1;
            float fresnel = pow(1.0 - abs(dot(rd, n)), 3.0);
            vec3 refractDir = refract(rd, n, 1.0 / ior);
            
            if(length(refractDir) > 0.0) {
                // March inside to find exit point
                float t2 = 0.02;
                bool exited = false;
                for(int j = 0; j < REFRACT_STEPS; j++) {
                    vec3 p2 = p + refractDir * t2;
                    float d2 = -map(p2);
                    if(d2 < REFRACT_PRECISION) {
                        vec3 n2 = -getNormal(p2);
                        vec3 exitDir = refract(refractDir, n2, ior);
                        
                        if(length(exitDir) > 0.0) {
                            // Continue ray from exit point
                            ro = p2 + exitDir * 0.01;
                            rd = exitDir;
                            t = 0.0;
                            exited = true;
                            break;
                        }
                    }
                    t2 += max(d2, 0.005);
                    if(t2 > 5.0) break;
                }
                
                if(!exited) {
                    // Absorbed inside
                    col = background(rd);
                    break;
                }
            } else {
                // Total internal reflection
                col = background(rd);
                break;
            }
        } else {
            t += d * MARCH_STEP_SCALE;
            if(t > 10.0) {
                col = background(rd);
                break;
            }
        }
    }
    col *= 4.;
    col -= 1.3;
    
    fragColor = vec4(col, 1.0);
}

Image

Not used

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