Does it cost performance to send custom vertex data via surfacetool?

Mr_Lime

I was wondering about this because technically if you send more data to the GPU, I would think that it costs more performance. I personally think that not using "set_custom()" via surfacetool would not send any data in the CUSTOM-attributes of a vertex, but you can alway access them in a vertex-shader using CUSTOM with 0 as standart values, so either a standart value has to always be send or the shader defaults to 0.
I basically want to know which one it is and if it can impact performance.
Im pretty new with shaders and right now I dont need any performance boost, but I'm trying to learn how they work and that includes knowing where you can save performance 🙂

Toxe

Mr_Lime It's always best to just measure and benchmark.

xyz

Mr_Lime A shader can always access any declared vertex attributes, regardless if you send actual data or not. Those customs are declared by Godot "under the hood". Sending will contribute to performance cost but it may not be much. It really depends on the hardware.

kuligs2

why dont you write a test and monitor the resource monitor in the debug window?