View Full Version : taking a value from spot info node, shifted in position

05-09-2012, 11:16 PM
Hi There

I've been scratching my head for a while over this…

Am trying to figure out how to take a reading from a spot info node, and then another reading from another spot some distance from it.
I'd then subtract one from the other to create the desired effect. But I haven't figure out how to 'shift' a spot info reading.

Any ideas?

05-09-2012, 11:25 PM
You can add null item. Then use Item Info to get World Position, and use Math > Vector > Distance with Spot Info > World Position as second parameter, it will give you distance between them.
If you will plug it to e.g. 2 color gradient you will receive something like circle. Move null item with VPR active, and you will understand nodes better.

ps. spot is just one - the one that's currently evaluated. Nodes are evaluated in reverse order - from right to the left. What's on right side is parent node, and what's on left is child node.

05-10-2012, 03:46 AM
Spot info doesnt really give info about any one, defined spot... its really giving info about ALL spots on a given surface at the same time, so your idea of shifting the spot doesnt really mesh.

perhaps it might be better to describe what you're trying to do, and where you spot info is "theoretically" fitting into your approach.

05-10-2012, 03:53 AM
Thanks Sensie & RebelHill

Actually, a bit more detail of what I'm after:
I want to evaluate every spot of the entire surface against every immediately adjacent spot (it does sound a bit CPU intensive when I put it like that).
I want to identify areas of sudden change in surface normals i.e. a fold, crease, or an edge, and gauge the magnitude of the normal change at those areas.

05-10-2012, 04:11 AM
Normally people use Occlusion node for things like this. But Occlusion is not taking into account normal vector but general geometry.

It sounds possible to write in custom node.

If you would convert normal map to real geometry (displacement), then you could use Occlusion to find irregularities.

05-10-2012, 04:48 AM
what about for angles beyond 180?
And sharpening up the edges?

Am actually trying to basically build a custom outline & edge shader. With gradient control over edge detection threshold, and distance from the edges.