Why does my Render Target 2D show stale content?

Render Target 2D persists between draws. Without Clear Render Target 2D, draws accumulate. Call ClearRenderTarget2D at the start of each frame's render flow.

Should I create a new RT each time?

For one-shot uses, allocate a transient RT via UKismetRenderingLibrary::CreateRenderTarget2D and release after. For per-frame reuse, allocate once and clear each frame — cheaper than recreating.

What's Draw Material to Render Target?

DrawMaterialToRenderTarget renders a material to the RT. Combined with ClearRenderTarget2D + per-frame draw, gives you a controllable canvas. Useful for procedural textures.

Fix: Unreal Render Target 2D Stale Between Draws

Quick answer: Call UKismetRenderingLibrary::ClearRenderTarget2D(this, RT, ClearColor) before each frame’s draw. RTs persist by design; clear when you want a fresh canvas.

RT shows traces of previous frames stacked on top of each other. RT wasn’t cleared between draws; the canvas accumulated.

The Symptom

Drawing to RT each frame produces a smear of every previous frame’s content. Looks like motion-blur but unwanted.

The Fix

void AMyActor::DrawToRT()
{
    UKismetRenderingLibrary::ClearRenderTarget2D(this, RT, FLinearColor::Transparent);
    UKismetRenderingLibrary::DrawMaterialToRenderTarget(this, RT, DrawMat);
}

Clear, then draw. Each frame starts fresh.

BP Equivalent

BP graph:
  Clear Render Target 2D(RT, ClearColor)
  Draw Material to Render Target(RT, Material)

Verifying

RT shows current frame only. Without clear: accumulates. Use Show RenderTargets in editor to inspect live.

“Clear before draw. RT stays current.”

Related Issues

For UObject GC mid-task, see UObject GC. For Niagara skeletal stale, see skel data.

Clear. Draw. Repeat. RT clean.