Lua Scripting

[Swampdonkey]

I'm attempting to explore the Lua scripting capabalites of the engine, interesting to say the least! My question is - how do I access things like the camera and such from a Update function inside a loaded model?

 

In my models script I have this function

 

function Update(world)

 

Just to keep this question simple - say the model is a plain and I want to rotate it to face the camera each world update? I'm following the structure of the scripting system just fine - just not sure how to reference the camera in the model script since im not running a base game script for the map. The camera pointer should be set as a global i understand but if theres no game script in my setup where does the camera pointer get created so that I may access it via the models Update script?

 

Thanks again guys, I never relaized the capablities LE had until trying out this Eval, it's qute an amazing language!

[Canardia]

how do I access things like the camera and such from a Update function inside a loaded model?

fw.main.camera

 

say the model is a plain and I want to rotate it to face the camera each world update?

self.model:Point(fw.main.camera,3,0.1,0)

[Swampdonkey]

Come on Lumooja thats to easy.. I dare not try that

 

So am I understanding correctly that theres a base.lua script being called and this base script is setting all the globals that other scripts can use? I must admit globals throughtout a scripting language is a new one to mean, I can definitely see the benefits of having such capabilites.

 

If I was to build a set of models and included scripts for some of the functionality would referencing this 'fw.main.camera' remain true for others loading the model into their LE sandbox?

 

 

Thanks mate.

[Canardia]

Yes, fw.main.camera is always available, since fw is the global framework object, which Editor also uses for all the post-processing effects, water, etc....

[Swampdonkey]

Thanks, seem to have fully caught onto the lua tie-ends with LE now.. Its nice to have this control. One last question for today - are Lua scripts attached to models compilable outside of adding all my media to a zip file and password protecting it?

[Canardia]

Yes, the abstract file system doesn't care if the files are in a pak or not.

[Josh]

Lua scripts cannot be inside .pak files because the Lua dofile() function doesn't understand my own pak file system. DoFile() is the only way to execute a compiled script file, so I chose to use this method.

[VicToMeyeZR]

wanna shoot josh an email for your forums account to be updated?

[Niosop]

Are you wanting to compile for speed or to protect your scripts? There won't be much speed increase except for initial load because the scripts are compiled to bytecode as soon as they are loaded I think, so you'll get faster startup, but the same execution speed.

[macklebee]

i think he is just using the new evaluation demo

[Marleys Ghost]

Thanks again guys, I never relaized the capablities LE had until trying out this Eval

 

 

 

 

[macklebee]

ah... i knew i had read that somewhere...

[Swampdonkey]

Thanks for the replies, yah day 3 evaluating and so far LE is very very promising, have got some great results thus far. Wasnt really worried about compiling for speed more for the protection of the script but I suppose at this point thats irrelevant. Maybe some more info on what I'm attmepting will be helpful - I decided to make a custom boned tree trunk and apply mini prongs to it ala Speed-tree, wrote a script to manually animate the trunk and branches based off a given wind value. Prongs attached to the trunk joints act independant of the tree but update their location based on the tree branch swaying factor so they appear to be 100% attached.

 

All working great so far but I still think I'm missing something with the scripting language as the script runs fine on one tree but as soon as I add a 2nd tree of the same kind to the scene the script seems to only run on the last tree I insert into the scene. Prongs are forced to face the camera per render so its obvisious the script is running a single instance only?

 

One tree working fine, although a screenshot hardly shows the problem here -

 

http://gothasoft.com/temp/atree1.jpg

 

Not the prettiest tree but tosed together rather quickly for testing the scripts.

[VicToMeyeZR]

ah lol. my bad. good deal.

[Josh]

Can you post your script?

[Canardia]

Sounds to me like you are rewriting the global Update function instead of adding a model's own Update function.

[Swampdonkey]

Well I found two problems when going back through my script, globalizing and just some bad referencing on my part but all fixed.. screenie shows numerous trees all behaving to the script now.

 

http://gothasoft.com/temp/atree2.jpg

 

Now to work on some grass/foliage and terrain textures.. Thanks for the support. I'm going to have to buy a license now just for all the help I've been recieving - rather I choose to use LE or not heh.

 

PS: spec alpha layer is a bit hard on those prong textures - causing some see through holes but easily fixed.

[Josh]

Are you using billboards that point towards the camera, like SpeedTree does? If you are, it would be much more optimal to control this behavior in a vertex shader. It would be a little tricky, but the benefit is the GPU would handle everything at no cost, and you would not have to loop through and adjust entities in script. You would also be able to render all leave sections in a single pass, which is much more optimal. That might be something to think about, in the long term.

[Swampdonkey]

Ah yes I am pointing the smaller prong billboards tot he camera ala Speedtree - was just sitting here thinking of some optimizations. I Had wrote a shader for treeparty GDK that rotated the billboards to the camera. I'll see if I can salvage any of that shader code - if I recall it took quite awhile to make that shader so I hope some of it is reuseable.

 

I see no other way to adjust the trunk bones but to use the script but usually theres only 5 to 8 bones to sway so it should hurt to much there.. Im hoping.

 

 

Thanks for the pointer.

[Josh]

There's a chapter in GPU Gems 3 starting on page 373 that would be of particular interest to you.

[Swampdonkey]

Thanks, I got that book around here somewhere. Going to spend the day working on a shader to handle this job.

[flachdrache]

Its also available online -> nvidia.