Lưới Lập Phương Tâm Mặt (Face-Centered Cubic Lattice)

Designed with sdf2stl.saej.in

Untested. Print at your own risk.

Rendered with the following signed-distance function

// exponential smooth minumum of a and b, with smoothing factor k.
float smoothMin( float a, float b, float k)
{
float r = 1. + exp2(-abs(a-b)/k);
return min(a,b) - k * log2(r);
}

// A smooth face-centered-cubic lattice.
float sdSmoothLattice(vec3 position, float radius, float smoothness)
{
position -= round(position);
position = abs(position);
if(position.x + position.y > .5){
position.yx = vec2(.5) - position.xy;
}
if(position.x + position.z > .5){
position.zx = vec2(.5) - position.xz;
}
if(position.y + position.z > .5){
position.zy = vec2(.5) - position.yz;
}
vec3 v = vec3(1., -1.,0.)/sqrt(2.);
return smoothMin(smoothMin(smoothMin(smoothMin(smoothMin(
length(position - dot(position, v.xxz) * v.xxz) - radius,
length(position - dot(position, v.xyz) * v.xyz) - radius, smoothness),
length(position - dot(position, v.xzx) * v.xzx) - radius, smoothness),
length(position - dot(position, v.xzy) * v.xzy) - radius, smoothness),
length(position - dot(position, v.zxx) * v.zxx) - radius, smoothness),
length(position - dot(position, v.zxy) * v.zxy) - radius, smoothness
);
}

float map(in vec3 position)
{
vec3 q = abs(position);
float n = 8.;
float k = 100./n;
return max(
sdSmoothLattice(position / k + .5, .6/k, .15/k) * k,
max(max(q.x,q.y),q.z)-50. - .6
);
}