# How to make hair particles (grass) bend on z axis

I created a grass animation with hair particles, but I cannot get the grass to bend (on the z axis) it just sways from side to side on the x axis.
screenshots, more screenshots, link to video.

I have created an empty and assigned a texture to it, then linked the particles through the texture and I can control the animation of the grass through the empty but when I move the empty on the Z axis it just pushes the grass to the side without any bending.

Any help on this would be appreciated. cheers. If you need any more info let me know.

• I don't understand quite how you are setup, could you be more specific? (maybe some screenshots? I couldn't tell from the video what was wrong).. Are you using hair dynamics? – gandalf3 Jul 26 '13 at 1:17
• Also don't follow I have created an empty and assigned a texture to it, can you explain how the texture effects the particles exactly? – ideasman42 Jul 26 '13 at 6:19
• @gandalf3 link updated to show screenshots. Hope it helps. – Lindsey Jul 26 '13 at 8:55
• @ideasman42 screenshots available. I assigned a texture(marble ) to the mesh (hair emitter) then added a force field (texture force field) and then I assigned the texture to the empty that appeared adn the empty with the texture is linked to the hair emitter which controls the movement of said emitter. if you need any more info let me know and i hope the screenshots help as well. – Lindsey Jul 26 '13 at 9:01
• @Lindsey the the updated links still don't seem to be working. You can add images right into the post without uploading to another site first. Using Hair dynamics will simulate the hair particle (takes a lot longer) – gandalf3 Jul 30 '13 at 20:57

I'm not sure I understand the question completely, but I'll start with some possible solutions:

# Hair Dynamics:

Using hair dynamics will simulate the strands with cloth physics,

Some examples with a wind force:
With hair dynamics:

Without hair dynamics:

If you really want to simulate it (Note, simulation probably takes longer and you can most likely do it satisfactorily other ways) you can use a Smoke simulation to get the airflow infromation and then use a Smoke Flow force to use it to effect the grass:

(The advantage to this is that you get all the complex little air currents caused by the cube as the air flows around it to effect the grass)

# Texture Force field

I'm not sure what you mean by not bending (Is it not bending in the viewport? or only when rendered?)

Texture force with Dynamics:

And without:

• It is ok. But what would you do if you had to use an object particle render with some more complicated plant. – Oleksiy Plotnyts'kyy Feb 8 at 17:19
• @OleksiyPlotnyts'kyy Unfortunately I don't think that's possible with the current particle system. (I'm not sure, but you may be able to make something work with animation nodes, though I doubt it'll be very performant. Perhaps worth asking about in a new question either way). Otherwise, you could fake it by rigging + animating the plants with some randomized swaying animations (see blender.stackexchange.com/q/23850/599) – gandalf3 Feb 9 at 5:29

Try adding a force field to your scene.

A wind force with a small strength will make the strands lean over slightly, turning up the noise will cause them to vary and bend along the length of the strand.

A Turbulence field can also be used to add random movement to the strands.

You also have the option of adding two force field settings within the particle options.

• i have followed you advice and all it did is makr the grass sway faster still no bending in the grass particle – Lindsey Jul 30 '13 at 8:14