Data commit

Task/Death-Star/Lua/death-star.lua

@@ -0,0 +1,42 @@
+function V3(x,y,z) return {x=x,y=y,z=z} end
+function dot(v,w) return v.x*w.x + v.y*w.y + v.z*w.z end
+function norm(v) local m=math.sqrt(dot(v,v)) return V3(v.x/m, v.y/m, v.z/m) end
+function clamp(n,lo,hi) return math.floor(math.min(math.max(lo,n),hi)) end
+function hittest(s, x, y)
+  local z = s.r^2 - (x-s.x)^2 - (y-s.y)^2
+  if z >= 0 then
+    z = math.sqrt(z)
+    return true, s.z-z, s.z+z
+  end
+  return false, 0, 0
+end
+
+function deathstar(pos, neg, sun, k, amb)
+  shades = {[0]=" ",".",":","!","*","o","e","&","#","%","@"}
+  for y = pos.x-pos.r-0.5, pos.x+pos.r+0.5 do
+    for x = pos.x-pos.r-0.5, pos.x+pos.r+0.5, 0.5 do
+      local hitpos, pz1, pz2 = hittest(pos, x, y)
+      local result, hitneg, nz1, nz2 = 0
+      if hitpos then
+        hitneg, nz1, nz2 = hittest(neg, x, y)
+        if not hitneg or nz1 > pz1 then result = 1
+        elseif nz2 > pz2 then result = 0
+        elseif nz2 > pz1 then result = 2
+        else result = 1
+        end
+      end
+      local shade = 0
+      if result > 0 then
+        if result == 1 then
+          shade = clamp((1-dot(sun, norm(V3(x-pos.x, y-pos.y, pz1-pos.z)))^k+amb) * #shades, 1, #shades)
+        else
+          shade = clamp((1-dot(sun, norm(V3(neg.x-x, neg.y-y, neg.z-nz2)))^k+amb) * #shades, 1, #shades)
+        end
+      end
+      io.write(shades[shade])
+    end
+    io.write("\n")
+  end
+end
+
+deathstar({x=20, y=20, z=0, r=20}, {x=10, y=10, z=-15, r=10}, norm(V3(-2,1,3)), 2, 0.1)