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I'm making another branch for my tree model this time I want it to look like a white pine that I modeled it off of google images. The leaves should be moving more upward in a V shape/ cone shape while maintaining a puff ball design. However, there still pointed outward from the face of the mesh I tried playing around with the ParticleSystem property tab's menu such as using "object" in "render as" then selecting the leaf model in "instance object" and for the vertex groups I chose "density" by marking the areas in wightpaint mode so the leaves will only target the end tips of the branch, but this was the best I could do. Is there any other way I can reshape it?enter image description here

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  • $\begingroup$ i am not sure whether this is possible at all with particles...but for sure it would be possible with geometry nodes. $\endgroup$
    – Chris
    Sep 12, 2023 at 5:26
  • $\begingroup$ @Chris It is possible with Hair particles, but I guess Geometry Nodes would be better for performance. $\endgroup$ Sep 12, 2023 at 11:22

2 Answers 2

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Make sure you have enabled Advanced on the Hair settings. You can make them all point upwards (or downwards) by changing the settings for Tangent and Tangent Phase under Velocity. You can also add a small amount of randomness with Randomize so that they are not so uniformly oriented.

hair tangent velocity

//EDIT: As discussed in the comments, there are problems with the orientation of the leaves if you are changing the velocities for Tangent and Tangent Phase. It turns out that of course the face normals are always pointing outside perpendicular to the face, but (I did not know it before) the orientation of the UVs has an influence on the tangent.

So as a starting point let's have a closer look at one of the branches from your model (I have disabled the leaves and made the paths shorter for a better overview, also I show Edit Mode and Object Mode in comparison). This is how the UVs of the branch look and how the paths are oriented without any velocity for the tangents:

initial state

First of all you can see that the UVs are quite messed up in comparison to the actual mesh. I will talk about the UVs later.

Then you can see how the orientation towards the tip is changing from sideways to forward, simply speaking. Imagine that when you now rotate all 45° away in some direction from their upright position according to the normal, the ones already pointing in the desired direction will stray away from it.

What I recommend is deleting the very last face on the top closing the branch. The leaves should cover up the hole if you do not look too close and you can also scale it smaller maybe. Now you can see, all hair paths are pointing sideways from the branch, none are pointing forward.

deleting the top face

Notice that the only real UV face is now gone, meaning the other branch UVs are just edges in the UV map. And if you now give a bit of velocity on the Tangent and Tangent Phase, the result looks terrible and they are all oriented differently:

different orientations

Then I realized that the different orientation of the UVs could be a reason for the paths changing directions. Taking the individual edges in the UV map, leaving one as it is, rotating one by 90°, the other by -90° and the last by 180°, the paths looked a lot better:

new orientation of UVs

However, it was just a guess as how to rotate the edges. And maybe not all UVs are oriented in a way that makes guessing easy. So I thought giving the mesh a new UV unwrap would be better, and I used U > Smart UV Project, which is always good for a quick automatic unwrap. The result is better than the initial mess, but not as good as the manual rotation before:

smart uv project

They are also (for the most part) pointed in the opposite direction of what is desired. This could of course be changed with the velocity for Tangent and Tangent Phase or by just rotating the UVs by 180° in the UV Map:

rotating the UVs

Still not perfect. So I thought I should make all UVs basically the same. Therefore you can choose U > Reset as unwrapping method. This simply places each face individually onto the UV map so that it fits the area, in the case of quads they just become squares filling the complete UV map:

reset uv faces

This gives a quite good result, and if you could spot a face where the paths are oriented differently than all the others, just select this one and rotate it 90°, 180° or 270° until it is correct. If you now add a little Randomize velocity to make it appear a little more natural it should be okay:

randomize velocity

Here is the final result (your file did not contain the wood textures, so I just gave a color to the branch):

final branch

By the way, I have disabled Rotation in the particle settings - but the values for Phase and Randomize Phase still have an influence on how the leaves look, enabling Rotation just lets you edit those values:

changing rotation phase

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  • $\begingroup$ I copied what you wrote in the image but after tweaking with tangent, tangent phase, randomize I still wasn't able to get the leaves to point up they just look like puff balls. $\endgroup$
    – Stephen
    Sep 12, 2023 at 18:33
  • $\begingroup$ @Stephen I imported your mesh into my file and put my hair system onto your mesh and it did not work either. I even applied the Subdivision Surface modifier which did not help, took just a ring of the subdivided mesh and extruded it to get new faces. Did not work. But eventually I found the reason: it's the UVs. So I went into Edit Mode, selected all and hit U > Smart UV Project, and now it worked. You could also just choose Reset, the values for Tangent and Tangent Phase will be different, but both will make it work. $\endgroup$ Sep 12, 2023 at 20:21
  • $\begingroup$ It seems to be working but how do you reset? $\endgroup$
    – Stephen
    Sep 12, 2023 at 22:38
  • $\begingroup$ Also, I notice that any branch above the horizontal 90-degree mark have their leaves pointed upward but any branch pointed below the horizontal mark have their leaves facing downward, why does it do that, and can it be fixed so they can all be pointed upwards? $\endgroup$
    – Stephen
    Sep 13, 2023 at 0:19
  • $\begingroup$ @Stephen Reset is one of the unwrapping options, press U > Reset. After testing I think it is the better option to make the leaves point more in the same direction, because the orientation of the UV faces makes a difference for the Tangent. But since they are oriented along their normals, the ones on the closing faces of each tip will always be pointing in different directions than the ones on the side, so I would rather leave the tip open to have only leaves pointing outwards the side of the branches and not "forward" from the tip. I'll edit in examples in my answer later. $\endgroup$ Sep 13, 2023 at 5:58
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You could make the pines go one direction this way, enable the Advanced option, disable Hair Dynamics, enable Rotation, and select Orientation Axis > Velocity/Hair:

enter image description here

Then create a Force Field like for example a Force and give it a negative Strength, the pines will be attracted towards the force field:

enter image description here

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  • $\begingroup$ Using a force field seems a bit elaborate and complicated to me... will the pines keep the orientation when instanced on a tree or do you have to instance force fields with them? Have no object to test it atm. $\endgroup$ Sep 12, 2023 at 11:20
  • $\begingroup$ You can duplicate your branch and rotate a bit, they will roughly keep the same orientation, then convert the particles to mesh and use the branches as particles themselves, or Alt D? $\endgroup$
    – moonboots
    Sep 12, 2023 at 11:55
  • $\begingroup$ It does seem to work but the leaves all follow the same force when I want them to point out in different directions based on the branches. This is especially noticeable when I crank up the strength. $\endgroup$
    – Stephen
    Sep 12, 2023 at 23:46

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