Task: Death Star







Python: import sys, math, collections

Sphere = collections.namedtuple("Sphere", "cx cy cz r")
V3 = collections.namedtuple("V3", "x y z")

def normalize((x, y, z)):
    len = math.sqrt(x**2 + y**2 + z**2)
    return V3(x / len, y / len, z / len)

def dot(v1, v2):
    d = v1.x*v2.x + v1.y*v2.y + v1.z*v2.z
    return -d if d < 0 else 0.0

def hit_sphere(sph, x0, y0):
    x = x0 - sph.cx
    y = y0 - sph.cy
    zsq = sph.r ** 2 - (x ** 2 + y ** 2)
    if zsq < 0:
        return (False, 0, 0)
    szsq = math.sqrt(zsq)
    return (True, sph.cz - szsq, sph.cz + szsq)

def draw_sphere(k, ambient, light):
    shades = ".:!*oe&
    pos = Sphere(20.0, 20.0, 0.0, 20.0)
    neg = Sphere(1.0, 1.0, -6.0, 20.0)

    for i in xrange(int(math.floor(pos.cy - pos.r)),
                    int(math.ceil(pos.cy + pos.r) + 1)):
        y = i + 0.5
        for j in xrange(int(math.floor(pos.cx - 2 * pos.r)),
                        int(math.ceil(pos.cx + 2 * pos.r) + 1)):
            x = (j - pos.cx) / 2.0 + 0.5 + pos.cx

            (h, zb1, zb2) = hit_sphere(pos, x, y)
            if not h:
                hit_result = 0
            else:
                (h, zs1, zs2) = hit_sphere(neg, x, y)
                if not h:
                    hit_result = 1
                elif zs1 > zb1:
                    hit_result = 1
                elif zs2 > zb2:
                    hit_result = 0
                elif zs2 > zb1:
                    hit_result = 2
                else:
                    hit_result = 1

            if hit_result == 0:
                sys.stdout.write(' ')
                continue
            elif hit_result == 1:
                vec = V3(x - pos.cx, y - pos.cy, zb1 - pos.cz)
            elif hit_result == 2:
                vec = V3(neg.cx-x, neg.cy-y, neg.cz-zs2)
            vec = normalize(vec)

            b = dot(light, vec) ** k + ambient
            intensity = int((1 - b) * len(shades))
            intensity = min(len(shades), max(0, intensity))
            sys.stdout.write(shades[intensity])
        print

light = normalize(V3(-50, 30, 50))
draw_sphere(2, 0.5, light)


VB: 

option explicit               

const x_=0
const y_=1
const z_=2
const r_=3

function clamp(x,b,t) 
  if x<b then 
     clamp=b 
  elseif x>t then
    clamp =t 
  else 
    clamp=x 
  end if 
end function

function dot(v,w) dot=v(x_)*w(x_)+v(y_)*w(y_)+v(z_)*w(z_): end function

function normal (byval v) 
    dim ilen:ilen=1/sqr(dot(v,v)): 
    v(x_)=v(x_)*ilen: v(y_)=v(y_)*ilen: v(z_)=v(z_)*ilen:
    normal=v:
end function

function hittest(s,x,y)
   dim z
   z = s(r_)^2 - (x-s(x_))^2 - (y-s(y_))^2
   if z>=0  then
     z=sqr(z)
     hittest=array(s(z_)-z,s(z_)+z)
   else
     hittest=0
  end if
end function
            
sub deathstar(pos, neg, sun, k, amb)
  dim x,y,shades,result,shade,hp,hn,xx,b 
  shades=array(" ",".",":","!","*","o","e","&","#","%","@")
  for y = pos(y_)-pos(r_)-0.5 to pos(y_)+pos(r_)+0.5 
    for x = pos(x_)-pos(r_)-0.5 to pos(x_)+pos(r_)+.5
      hp=hittest (pos, x, y)
      hn=hittest(neg,x,y)
      if not  isarray(hp) then
         result=0
      elseif not isarray(hn) then
        result=1
      elseif hn(0)>hp(0)  then
        result=1        
      elseif  hn(1)>hp(1) then
        result=0
      elseif hn(1)>hp(0) then
        result=2
      else
        result=1
      end if

      shade=-1
      select case result
      case 0
        shade=0        
      case 1
        xx=normal(array(x-pos(x_),y-pos(y_),hp(0)-pos(z_)))
        
      case 2
        xx=normal(array(neg(x_)-x,neg(y_)-y,neg(z_)-hn(1)))
        
      end select
      if shade <>0 then
        b=dot(sun,xx)^k+amb
        shade=clamp((1-b) *ubound(shades),1,ubound(shades))        
      end if       
      wscript.stdout.write string(2,shades(shade))
    next
    wscript.stdout.write vbcrlf
  next
end sub

deathstar array(20, 20, 0, 20),array(10,10,-15,10), normal(array(-2,1,3)), 2, 0.1