How do the new 4.2.0 attached dynlights work?

[Matt]

How do we attach them, remove them, define them, etc.?

If this is documented anywhere it should be linked in the wiki entry for [wiki]Dynamic light[/wiki].

[Blue Shadow]

There are functions. That's about all I know.

[Rip and Tear]

I haven't been able to play around with it yet, but it seems like this doesn't allow for the same level of dynamic light manipulation as ZScript-defined lights. Not being able to add custom behavior to a light's tick makes this a no-go for my use case.

[Graf Zahl]

If you want to custom-manipulate a light you'll have to call A_AttachLight with the same light ID repeatedly in the tick function. The lights themselves are now pure renderer side objects for performance reasons. The function allows changing all properties a light can have.

[Caligari87]

Performance question then: In DarkDoomZ my flashlight works by having an inventory item spawn a dynamic light as a world actor since it sways and rotates somewhat independently of the player. Obviously with large radius lights and constant light movement, this leads to performance issues on maps with lots of linedefs, due to relinking I presume.

Would I gain any appreciable performance if I used an attached light on a dummy world actor or the player? Or is it going to be negligible in comparison to the movement relinking I presume will still be happening?

Link to my dynamic light class for reference

[Graf Zahl]

That won't make any difference. The light linking didn't get any faster with the change, the main advantage is that it doesn't require a full actor and all its overhead just to attach a light to a single state.

[Apeirogon]

So now I cant do

Code: Select all

class light : pointlight {}

in zscript file and need create light definition in gldefs and then constantly (re)attach it to actor? Am I right?

If no, tell me a way to create dynamically controlled dynamic light.

[Caligari87]

That won't make any difference. The light linking didn't get any faster with the change, the main advantage is that it doesn't require a full actor and all its overhead just to attach a light to a single state.

Thanks for the clarification! I suppose I'll leave it as-is, since a single actor isn't much overhead.

[22alpha22]

So now I cant do

Code: Select all

class light : pointlight {}

in zscript file and need create light definition in gldefs and then constantly (re)attach it to actor? Am I right?

If no, tell me a way to create dynamically controlled dynamic light.

I'm pretty sure the old lights are sticking around, otherwise that would break compatibility with older mods which isn't something usually done.

[Matt]

What's a lightid?

[Graf Zahl]

What it says on the plate. It's an identifier for the light, so you can call the function repeatedly on the same light. The number is maintained per actor and entirely in user space, i.e. it's you who decides what number to use.

[Matt]

How are they defined then? Is there a light struct within the Actor class?

[Graf Zahl]

They are defined by calling A_AttachLight. Yes, there is a list of attached lights in each actor, and the lights in there are searched by the ID.