Read Grid 2D Collection in Particle Update Stage in Niagara

[kk_stu]

Has anyone succeed to access the specified cell of a Grid 2D Collection in a Scratch Pad in the Particle Update stage in Niagara System?

What I want to achieve;
-Niagara System contains two elements; Grid 2D Collection and grid-shaped layout particles, whose resolutions are the same
-Contain 2D simulation result in a Grid 2D Collection
-Assign the simulation result as an attribute of corresponding particles

What I’ve tried;
-Create a Scratch Pad in the Particle Update stage
-In the Scratch Pad, add a Get Previous Float Value node that takes the Grid 2D Collection input as a reference

Issue;
-Execution of the stages in the particle emitter stops at the Scratch Pad
-Even if I specified the index of the cell to read (like {0, 0}), the result was the same
-No error messages on the Niagara Logs

Any help is appreciated.

[kk_stu]

The version of the Unreal Engine is 5.4.4.
Thanks!

[NuShrike1]

I’ve been using Grid2D’s SamplePreviousGridFloatValue in Unreal Engine v5.5.4 (DirectX) in Niagara in ParticleUpdate and I’ve been getting valid values out of it. It’s also working under Meta’s UE fork v5.5.1 (DirectX).

It seems to be working now?

I’ve been only fetch single-value floats so far, and I did initialize a matching size of the grid vs my render-target. I did not bind the Grid2D to the render-target as the option has in SetParameter as that clears my RenderTarget to (0.5, 0, 0, 0) (RGBA).