classes/class_multimesh

[giscus[bot]]

classes/class_multimesh

Inherits: Resource< RefCounted< Object Provides high-performance drawing of a mesh multiple times using GPU instancing. Description: MultiMesh provides low-level mesh instancing. Drawing thousands ...

https://docs.godotengine.org/en/stable/classes/class_multimesh.html

[railwaybird]

Clearing the buffer (i.e., data loss) when changing instance_count is not the most obvious behavior, and it caused a bug in my project that was hard to track down. This is a very important peculiarity of MultiMesh that I would have been glad to know about earlier, if it had been mentioned at the top of this page and in the class comments in the C++ code.

[Calinou]

It's already mentioned in the instance_count description, so I'm not sure if it should be mentioned in the class description as it would be redundant. One exception would be if there are "external" sources that can change instance_count without the user explicitly setting it, in which case a mention in the class description would make sense.

We generally try to keep C++ code comments about implementation details, rather than a copy of the class reference. Otherwise, the C++ code comments can quickly end up outdated compared to the class reference (or the other way around).

[wbf22]

I had the same issue as railwaybird I believe. (in c++)

Ran into the problem trying to remove instances. Might be nice to have a 'remove_instance(instanc: int)' method

[AJ213]

For those trying to use set_buffer_interpolated or set_buffer I would refer to the RenderingServer documentation which goes more into details on how to set the packed float array https://docs.godotengine.org/en/stable/classes/class_renderingserver.html#class-renderingserver-method-multimesh-set-buffer

Also, the reason I ended up using set_buffer_interpolated is you may not want the color or custom data to also interpolate. Which is my case since I pass vertex animation texture data through the custom data. To do that, whenever you set the current buffer data you also set the previous so that they are always the same (meaning, the interpolation result gives the same value).

This example is in Godot-Rust, but should be very similar in GDScript:

let instance_id_data = instance_id as usize * 20;
self.buffer[instance_id_data+16] = custom_data.r; // both are PackedFloat32Array
self.prev_buffer[instance_id_data+16] = custom_data.r; 

[wbf22]

I had the same issue as railwaybird I believe. (in c++)

Ran into the problem trying to remove instances. Might be nice to have a 'remove_instance(instanc: int)' method