particle system with particles that conform to surface

Question

I would like to create a particle system or hair in which the particles conform to the surface.

For instance, a particle system of a special object such as a long cylinder, which can be conformed to the surface of a sphere in random arrangements with paths that are randomized. I would like to arrive at something similar to this image:

Is this possible?

I thought about doing it via a particle system of bezier curves on a sphere and then applying a modifier to the curves, but I believe this would require doing it with a script and I haven't yet figured out how to do all of the scripting. Is there a simpler manner to do this?

I have tried creating a hair emitter with a empty force field sphere object (negative value for force at -1) and a collision sphere object, but the hair does not coalesce around the sphere. Instead I just get this:

It appears that the hair does not have segments which are allowed to bend.

Furthermore, I would like to have an object which will follow these paths created by the hair or emitter such as this:

Such that I can get a close up image of the interface such as this:

This code shows some of my difficulty in getting the particle system entities to be flexible and conform to a surface:

import bpy
import math

def reset():
    # Set to Object mode initially
    bpy.ops.object.mode_set(mode='OBJECT', toggle=False) 

    # Delete all objects in project at current
    for i in bpy.data.objects:
        bpy.data.objects[i.name].select = True
    bpy.ops.object.delete()

    # Delete all materials in curent project
    for i in bpy.data.materials[:]: 
        bpy.data.materials.remove(bpy.data.materials[i.name])

    # Set background to white
    world = bpy.context.scene.world
    world.horizon_color = (1,1,1)

    # Add a camera
    bpy.ops.object.camera_add()
    obj_camera = bpy.data.objects["Camera"]
    obj_camera.location = (10,-10, 8)
    obj_camera.rotation_euler = (math.pi/3, 0, math.pi/4)



reset()

bpy.ops.mesh.primitive_uv_sphere_add( \
    size = 1, \
    view_align = False, \
    enter_editmode = False, \
    location = (0, 0, 0))
ob = bpy.context.active_object
ob.name = 'Collision Sphere'
ob.show_name = True
col_sph = bpy.data.objects['Collision Sphere']
bpy.ops.object.modifier_add(type='COLLISION')

bpy.ops.mesh.primitive_uv_sphere_add( \
    size = 1, \
    view_align = False, \
    enter_editmode = False, \
    location = (0, 0, 0))
ob = bpy.context.active_object
ob.name = 'Emitter'
ob.show_name = True
em_sph = bpy.data.objects['Emitter']

bpy.ops.object.empty_add( type = "SPHERE", location=(0,0,0))
ob = bpy.context.active_object
ob.name = 'Force'
ob.show_name = True
force_sph = bpy.data.objects['Force']
bpy.ops.object.forcefield_toggle()
force_sph.field.strength = -1
bpy.ops.object.group_add()


bpy.context.scene.objects.active = em_sph
bpy.ops.object.particle_system_add()
psys1 = em_sph.particle_systems[-1]
psys1.name = 'Tubes'
psys1.use_hair_dynamics = True
pset1 = psys1.settings
pset1.name = 'TubeSettings'
pset1.type = 'HAIR'
pset1.use_hair_bspline = True
pset1.effector_weights.group = bpy.data.groups["Group"]
pset1.effector_weights.gravity = 0
pset1.effector_weights.apply_to_hair_growing = True

This gives just a spiky ball, without any bending of the hair. Any suggestions?

Answer 1

The obvious answer would be to use the hair simulation.

Create a hair emitter object an empty forcefield object and a sphere collision object. On the hair emitter decrease gravity to 0, enable hair dynamics with a large step size (like 20+).

Place the empty with the forcefield and your sphere with collision enabled within the emitter object.

On the hair emitter hit "bake" in the hair dynamics tab. Like 20 frames should do for the particles to settle around the collision object.

You should get something like this:

Now just tweak the hair length and strand thickness and select a shader. Done