Instancing Geometry - Base Mesh Displacement solution?

Each morning I often try and do the solution to the previous days class to test what I learned.

When I did the displacement to the base mesh for forest I found I did two things differently -
• I didn’t use a Position Node
• I used the Set Position Node: Offset socket instead of Set Position: Position socket

I think it achieved the same result but I thought I’d ask what the difference might be here?

(screenshots below)


Using a node means values depend on the scene configuration.
Entering values are fixed.

Connecting dots of the same color is no problem.

Purple dots are vectors, giving direction (pointing to) of a property, like a light direction, light intensity…


As far as I know, they are identical as far as function goes. If I had to guess why the instructor decided to do it that way, I’d say that he did it to make the vector manipulation more explicit.

When you don’t plug in a value into the position socket of the set-position node, it defaults to using the current value of the position attribute, and the offset just adds the vector to the current position. So you could get rid of the add node entirely.

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Hi Rawz

I tend to use the offset socket of the set position node when I just need to move geometry or points etc. I only use the position input when I an explicitly give geometry completely new points.
So in the case of displacement, I just want to offset existing geometry from its original position.
However, If i wanted to take a piece of geometry, maybe a plant or rock, and move it to a new position, I would use the position input in Set Position, instead of Offset, because I’m not trying to offset its position, I’m giving it a new position.
I think you might be right that you’re solution would work in most cases, particularly because the original position is being referenced anyway. Its just the way I’ve always did it.

Thanks for everyone’s replies.

I might have given the wrong idea about my question by leaving the Position Node visible in the ‘Alternative Solution’ - I didn’t use a Position Node in my solution, I just put it in the screenshot to show the similarities between the two.

@zeRgenTa thanks for clarifying how a Position Node would set or override a current position attribute.

@StephenWoods thanks, that gives great context to and explains the different use cases in a sort of ‘big to small’ way - setting the position of original base meshes then offsetting any subsets of those meshes is what I get from this.

As general feedback I would say I find the technical detail of nodes overwhelming sometimes so what I find I am doing is going back over each tutorial, breaking it down and repeating it in smaller parts for each main section of the node system.

This way I am putting together and using smaller groups of nodes almost by muscle memory, building practical use cases while I learn the deeper mechanics over time.

I do love it though! I have learned the basics of Python and C# for games in recent years but know I don’t really have the head for it and wouldn’t have any time for drawing if I continued. Nodes is the best combination of ‘coding’ and creating.

Thanks everyone.


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