# 2019.03.14 -> 2022.10.06 ->

# signed distance field compositing
# *spatial culling shader code
_matrix   = Matrix.TR(oriel.pos, oriel.rot)
_dim      = oriel.dimensions
MAX_STEPS = 256±
MAX_DIST  = 100±
BoxSD(pos, dim):
  q     = abs(pos) - dim
  step  = length(max(q, 0.0))
  step += min(max(q.x, max(q.y, q.z)), 0.0)
  return step
Raymarch(origin, dir):
  origin = mul(origin, _matrix)
  dir    = mul(dir,    _matrix)
  dist   = 0.0
  for (0..MAX_STEPS):
    pos  = origin + dist * dir
    step = BoxSD(pos, _dim / 2.0)
    if (step < 0.0001 or dist > MAX_DIST):
      then break loop
    dist += step
  return dist
YourPixelShader():
  pos = pixel.worldposition
  dir = normalize(pos - cam)
  // cull around
  dist = Raymarch(cam, dir) 
  clip(100 - (dist + 1))
  // cull between
  oriel = cam + dist * dir
  clip(dist(cam, pos) - dist(cam, oriel))
  ...