Rendering Agents

The crowd actor is simulation only: it tracks each agent's position, velocity, facing and ground height, but it draws nothing. You decide how agents look by reading their transforms each frame and feeding them to a renderer - typically an Instanced Static Mesh (ISM) so thousands of agents cost a handful of draw calls.

TIP

Every Blueprint graph on this page already exists, fully wired, in the BP_CrowdRenderer example Blueprint in the plugin's content folder (enable Show Plugin Content in the Content Browser). Open it to see the finished setup instead of rebuilding it.

Set up the renderer

Make an Actor with an Instanced Static Mesh component and assign the mesh your agents should use.

Instanced Static Mesh component on the renderer actor

What `GetAgentTransforms` gives you

Each transform is ready to render - no extra math needed:

Location - the agent's world position, including its tracked Z (see Ground Snapping).
Rotation - faces the agent's travel direction, holding the last facing while idle (so meshes don't snap back to identity). Tilted to the ground normal when bAlignTransformsToGround is on.
Scale - TransformScale on every axis (a property on the crowd actor).

Pass an empty array for all agents, or a list of indices to get just those.

The render loop

The simplest correct version, on your renderer's Tick:

This graph is already wired in BP_CrowdRenderer in the plugin's content folder.

TArray<FTransform> Transforms = Crowd->GetAgentTransforms({});

ISM->ClearInstances();
ISM->AddInstances(Transforms, /*bReturnIndices*/ false, /*bWorldSpace*/ true);

Updating in place (recommended)

ClearInstances + AddInstances every frame works, but rebuilds the whole instance buffer. When the agent count is stable, update transforms in place instead - add the instances once, then batch-update each tick:

This graph is already wired in BP_CrowdRenderer in the plugin's content folder.

if (ISM->GetInstanceCount() != Transforms.Num())
{
    ISM->ClearInstances();
    ISM->AddInstances(Transforms, /*bReturnIndices*/ false, /*bWorldSpace*/ true);
}
else
{
    ISM->BatchUpdateInstancesTransforms(0, Transforms, /*world*/ true, /*markDirty*/ true, /*teleport*/ true);
}

Hook the crowd's OnAgentsSpawned / OnAgentsRemoved events to resize only when the population actually changes.

Driving an animation

GetAgentVelocities and GetAgentSettled let you pick an animation state per agent (idle vs walk/run) without extra bookkeeping - feed the velocity magnitude into a per-instance custom data float and let the material/animation pick a pose from it. For a fully GPU-instanced animated crowd, combine this with a vertex-animation-texture material.