I'm trying to replicate material shading from Blender Internal in Cycles, so long I managed to get Diffuse working correctly with Point Lights, a rather awkward but working sunlight/hemi node setup, even a Specular shading similar to Blender Internal's Blinn.

But Cooktor Specular is not working out, I mean it's almost there, it kind of works, but for some reason my vector seem twisted away from the light source, making the final results, while rotating, to look really weird, here a picture to show the problem, also the node setup I'm using for that Specular in case someone want to replicate it. What I'm doing wrong? Or how do I replicate Cooktorr behavior correctly?

enter image description here

  • $\begingroup$ At first sight, shouldn't 'surface point' in your lightVector calculation come from Geometry>Position, not Geometry>Normal? I could be wrong.. $\endgroup$
    – Robin Betts
    Commented Apr 28, 2018 at 17:42
  • $\begingroup$ I use "normal" because for the shader to work need the surface point, "position" only gives the object's center. $\endgroup$ Commented Apr 28, 2018 at 17:55
  • $\begingroup$ ..not according to docs.blender.org/manual/en/dev/render/cycles/nodes/types/input/… .. but then, the rest of the tree isn't making much sense to me, yet, at least. $\endgroup$
    – Robin Betts
    Commented Apr 28, 2018 at 18:09
  • $\begingroup$ Oh your right, it's the position in world of a point of the surface, but still, for shading purposes I think normal is of more use to me, unless I got everything backwards, how would be the node setup in order to work with "position"? $\endgroup$ Commented Apr 28, 2018 at 18:53
  • $\begingroup$ You might find Paul Caggegis work on cycles toon shading of interest. $\endgroup$
    – sambler
    Commented May 1, 2018 at 19:13

1 Answer 1


Alright I found the issue, after reading the following observation about Cooktorr in blender dev:


I learned that Blender Internal Cooktorr was actually Blinn-Phong, so I reviewed the math of it and figured out which vector I had misplaced, I leave a picture with the solution, also the link to the math, for reference.




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