Hard coded variant

using Images, Colors, ImageView, LinearAlgebra, Gtk.ShortNames, StaticArrays, BenchmarkTools, ForwardDiff, FixedPointNumbers

## 1.750 ns (0 allocations: 0 bytes)
function scene(Pos::SVector{3})
  norm(Pos-SVector{3,Float64}(1.0,1.0,1.0))-50.0
end


## 66.728 ns (3 allocations: 128 bytes)
function ray_source(x::Real,y::Real,Pos::SVector{3},Direction::SVector{3},
        maxx::Int64,maxy::Int64,Sensorxv::SVector{3},Sensoryv::SVector{3})
  (SVector{3}(Pos+(maxx/2-x)/maxx*Sensorxv+(maxy/2-y)/maxy*Sensoryv),SVector{3}(normalize(Direction)))
end

##  17.810 ns (0 allocations: 0 bytes)
function gradient(scene,Pos::SVector{3})
  ForwardDiff.gradient(scene,Pos)
end

## 46.718 ns (0 allocations: 0 bytes)
function raymarch(scene,Pos::SVector{3,Float64},Normal::SVector{3,Float64},renderlim::Float64)
stepsize=1.0;
Start=Pos;
Strecke=0.0;
 while (stepsize > 0.001)
   stepsize=scene(Pos);
   Pos+=Normal*stepsize;
   Strecke+=stepsize
   if Strecke > renderlim
     return Gray{Normed{UInt8,8}}(0.25)
   end
 end
  Light = clamp(dot(gradient(scene,Pos),normalize(SVector(-1,-1,0))),zero(Normed{UInt8,8})
,one(Normed{UInt8,8}) ##shader not modular
)
  return Gray{Normed{UInt8,8}}(Light)
end

function run_it(y,x)
##y = 1920
##x = 1080

myPic = Array{Gray{Normed{UInt8,8}}}(undef,x,y)

SclY = 200.0
SclX = x/y *SclY
CamPosition = normalize(SVector{3,Float64}(1,-1,1))
Center = SVector{3,Float64}(0,0,0)
Normal = SVector{3,Float64}(normalize(Center-CamPosition))
Helper = SVector{3,Float64}(Center + SVector{3,Float64}(1,0,0))
Foot = SVector{3,Float64}(normalize(Helper-CamPosition) )
Ortho2 = SVector{3,Float64}(cross(Normal,Foot))
Ortho1 = SVector{3,Float64}(cross(Normal,Ortho2))



for i=1:x
  for j=1:y
     lpos, lnormal = ray_source(Float64(i),Float64(j),CamPosition,Normal,x,y,SclX*Ortho1,SclY*Ortho2)
     myPic[i,j]=raymarch(scene,lpos,lnormal,500.0) ## this allocates
  end
end
myPic
end