Particle rendering

Since Obi uses particles to represent all of its actors internally (cloth, ropes, fluids...), sometimes it makes sense to actually draw this particle-based representation in your scene: for debugging purposes, or as an alternative visualization mode. To render an actor's particles, just add an ObiParticleRenderer component to it. Any class that derives from ObiActor can have a particle renderer attached:

ObiCloth
ObiTearableCloth
ObiRope
ObiRod
ObiBone
ObiSoftbody
ObiEmitter

There are two particle renderer components: ObiParticleRenderer and ObiInstancedParticleRenderer (Obi 4.1 and above only). Let's take a look at each one:

Obi Particle Renderer

Particles are rendered as spherical impostors, which are just quads with a special shader applied. They are not actual sphere-shaped meshes (though they look like it), so thousands of them can be rendered at very little performance cost, without the need for GPU instancing support.

Here's how the inspector for ObiParticleRenderer looks:

Material

Material used to shade the particles. By default, a shader for the built-in render pipeline is used. There's a URP shader available too (ParticleShaderURP). You can also write your own custom shaders.

Render Parameters

Rendering parameters used when rendering the mesh that represents the particles. See Unity's documentation for details.

Particle Color

Tint color of your particles. This color will be multiplied by the particle's own color (solver.colors array, see scripting particles).

Radius scale

This scales the size at which particles are drawn.

Changing the radius scale does not affect the actual physical size of your actor's particles. It just draws them bigger or smaller than they really are. They will still use their real radii when involved in collisions, fluid interaction, etc.

Rope, cloth and fluid being rendered as particles.

Obi Instanced Particle Renderer

Particles are rendered as GPU instances of a mesh. They will accurately reflect particle position, orientation and scale. Note that this requires GPU instancing support, and the use of a instancing-enabled material.

Here's how the inspector for ObiInstancedParticleRenderer looks:

Render

You can disable this checkbox and the particles won´t be rendered.

Mesh

Mesh used for instancing.

Material

Material used for instancing. Note that it has to have its "Enable GPU instancing" property on.

The material used for rendering the chain must support GPU instancing, and if you're using the Compute backend, it must support indirect drawing. Obi includes an example of a ShaderGraph indirect instancing shader, which you can find at Obi/Resources/ObiMaterials/Common/Instanced/Compute/ProceduralInstanced.shadergraph.

Instance scale

This scales the size at which particles are drawn in the local X, Y and Z axis.

Changing the instance scale does not affect the actual physical size of your actor's particles. It just draws them bigger or smaller than they really are. They will still use their real radii when involved in collisions, fluid interaction, etc.

Particles w/rolling contacts being rendered as rock instances.