Objects cannot only be filled with particles, but it is also possible to cover their surface:
- Add a "Fill" emitter and drag the object meant to be covered with particles, to the emitter's "Body" slot.
- Set "Particle Distribution" to "Particle Layer".
- The emitter's "Emission" tab collapses and shows a reduced parameter set.
- In order to get a more or less dense particle distribution increase/decrease the fluid container's "Resolution".
- If the particle layer is not updated automatically, reset the scene: go to the timeline's last frame, and then back to frame 0.
Image: filling_objects_2_particle_layer_01
With the help of the "Texture" option it is possible to restrict the particle layer to the patterns of a shader or bitmap:
- Create a standard material and add a bitmap or a shader like noise to one of the channels, e.g. "Color".
- Drag the material's texture thumbnail to the "Texture" slot of the parameter.
- White parts of the image/shader will be used to create the particles.
- Reset, if necessary.
Image: filling_objects_2_particle_layer_02
Here's an image of a capsule with Cinema 4D's standard noise shader used as a mask for the particle layer: