RayMarching

float length(float2 v){
    return sqrt(v.x * v.x + v.y * v.y)
}

float signedDstToCircle(float2 p, float2 centre, float radius){
    return length(centre - p) - radius;
}

float signedDstToBox(float2 p, float2 centre, float2 size){
    float2 offset = abs(p - centre) - size;
    float unsignedDst = length(max(offset, 0));
    float dstInsideBox = max(min(offset, 0));
    return unsignedDist + dstInsideBox;
}

float signedDstToScene(float2 p){
float dstToScene = maxDst;

    for(int i = 0; i < numCircles; i++){
        float dstToCircle = signedDstToCircle(p, circles[i].centre, circles[i].radius);
        dstToScene = min(dstToCircle, dstToScene);
    }

    for(int i = 0; i < numBoxes; i++) {
        float dstToBox = signedDstToBox(p, boxes[i].centre, boxes[i].size);
        dstToScene = min(dstToBox, dstToScene);
    }

    return dstToScene;
}

float signedDstToScene (float3 p) {
    float dstToCube = CubeDistance(p, cube.centre, cube.size);
    float dstToSphere = SphereDistance(p, sphere.centre, sphere.radius);

    return max(dstToCube, dstToSphere * -1);
}

float smoothMin(float dstA, float dstB, float k){
    float h = max(k - abs(dstA - dstB), 0) / k;
    return min(dstA, dstB) - h * h * h * k * 1/6.0;
}

float signedDstToScene(float3 p){
    float dstA = dot(sin(p * paramA), 1);
    float dstB = dot(p % paramB, 1);
    return lerp(dstA, dstB, t);
}

float mandelbulb(float3 position){
    float3 z = position;
    float dr = 1;
    float r;

    for(int i = 0; i < 15; i++){
        r = length(z);
        if(r > 2)
            break;

        float theta = acos(z.z / r) * power;
        float phi = atan2(z.y, z.x) * power;
        float zr = pow(r, power - 1) * power * dr + 1;

        z = zr * float3(sin(theta) * cos(phi), sin(phi) * sin(theta), cos(theta));
        z += position;
    }
    return 0.5 * log(r) * r / dr;
}