Combining Multiple Fields

Hey all, having trouble with this particular video, I’ve posted a question in the video but I can’t see it pop up. I think there is a problem with the “ask a question” system today.

I have been following along. I’m sure there is an issue with my nodes. but the grass still comes through the rocks.
When I.: plug the nodes in any other pattern, either the rocks disappear or the whole thing does. Could anyone please point out and explain where I’ve gone wrong so. I understand what’s happening please?


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I have no experience with geo-nodes!
To be honest I don’t like the very abstract way to perform things in a piece of software which is build around a visual environment.

In the old way of using (grass) particles, we added particles and a weight paint property.
With this weight paint you could paint areas to influence the amount of (grass) particles.
Like 0 … 100% (more visuel, more understandable).

In your geo-nodes case, it looks the region of the stones isn’t wide enough to disable the growth of the grass particles. Probably a scaling problem in the math (or coordinates).

Maybe it will help you solve this problem.

unfortunately changing values hasn’t worked. ive tried to change the values of every node that appears to be relevant with no success. im sure its a flow issue i just cant see what it is exactly

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Which lecture is it part of doing, so we can look at what that has and may be able to spot a difference.



How did you keep the grass and rocks away from the trees? You used geometry proximity nodes based on the tree locations and float curves fit into the density factors of the relevant distribute points on faces nodes. If you want the grass to not be in the rocks, you have to play the same game, but using the geometry proximity based on the rock locations.

In the end you’ll probably want another “rock proximity” frame that looks a lot like your “proximity” frame, but that takes the rocks’ instancing points as input, instead of those for the trees. Then you would need to mix the outputs of the “proximity” and “rock proximity” frames using a math node via either a Min or a Multiply, before putting it into the density factor for the instancing points of the grass.

If you are following Stephen’s class closely, I think he ends up doing this several lessons down the road, after he replaces these placeholder shapes with the actual models for the scene.


EDIT: There is a known issue at the moment with adding images to questions on the new platform. For the time being, what you’ve done here is perfect.

If you have more questions involving images in the near future until this gets resolved, what I would recommend for now is to use the forum. We are still checking it, and most likely will be until issues like this are completely resolved on the new platform. Sorry for the headache!

It is the Combining Multiple fields lecture 3.10 in Geo Nodes course.
I have tried a few suggestions but it either complains that I’ve created a loop and gives me red lines, or my geometry completely disappears or part of it. I’m rather confused. in the lecture it’s hard to see exactly what’s connected to what as an overview because the screen is low dpi and zoomed in. not their fault. Just a note that there is no easy way without scrubbing through tons of video just to see the layout to compare. It could be useful in the future to have screenshots like the one I took with the overview available to view if there is trouble. Otherwise, the lectures are great.

| even loaded the geo nodes blend file that was available unfortunately it’s too far ahead and has things not discussed up to that lecture quite yet. which is ok, Strangely enough these tasks are actually simpler in Houdini lol I can do this task standing on my head with that lol. but yeah, it’s not as straight forward in blender, no idea why that is. but I guess it’s just a matter of time and some practice.

No worries, I figured something was up. I tried twice and waited for a bit to see if it would pop up, when it didn’t, I figured I’d just come here. The new site is much better than teachable. I’ve had a lot of frustrating moments with that. hence one of my last posts. but things are running smoother now. small bugs are to be expected. I was able to login, after that issue, I spent another $120 odd dollars that day and I’m happy as Larry. my issue was more that I was unable to reset my password on 2 sites teachable, and it wouldn’t let me login even after the success message, and wouldn’t let me login with the correct details that I could on the forum, plus I thought I had an issue with a claim but that wasn’t the case. But all’s good here and I’m still spending my money here even after some frustration so you know it’s still a good platform and the staff makes it easier.


Yes it is a problem with these big node trees. Even your image is only just readable.
May be using older hair systems was actually better!

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Hi Maize,

We cover add geoGeoproximity to the rock a bit further in, but its basically the same system as we used on the trees. The solution isn’t perfect, but in a very busy scene, it does the trick.


Thanks Stephen
I was able to get it to work this morning, I copied the whole tree pipe and adjusted the start and end nodes to be relevant to the rocks and grass. that did the trick

@NP5 old methods definitely worked but I feel like they were not as modular/ shareable and while less complex initially have less flexibility when you need more control. but they definitely work, no arguments there. Also, in terms of working in a team geo nodes provide a much better way to allow your team to reuse prebuilt systems. pretty much what Houdini is all about, but just less advanced as it’s not as aged as something like Houdini. still very capable. and free best of all. Hence why I’m trying to leave Houdini behind. my needs don’t justify the cost at this point. though I am much more proficient in its use. but yeah, I think there is still use for the older ways especially if the effect or thing you need is only small and doesn’t need to be repeated a lot.

It’s definitely something I was doing wrong. I just couldn’t find it. so, I deleted that section copied and pasted and made a few changes based on Stephen’s suggestion that it was the same as previously made node pipe.

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