transformgroups and lights

Engines, Libraries and Tools Xith3D Forums
#1

Should a light in a transformgroup move as the transformgroup is modified?? Currently my lights stay right where I set the initial position.

#2

[quote]Should a light in a transformgroup move as the transformgroup is modified?? Currently my lights stay right where I set the initial position.
[/quote]
What kind of light source? Because there are several ones.
AmbientLight and DirectionalLight don’t move because they are present on the entire scenery.

{Edit} For PointLight and SpotLight please see Yuri’s explanation below.

PS: To remove a (double) posting click the “Remove” icon on the right of the article’s head. In case it’s the only one in your thread it will be deleted, too.

#3

Hi,

[quote]However PointLight and SpotLight will move, in case you move the transformgroup where they’re in.
[/quote]
No, currently in Xith3D all the light positions and directions are defined in VWorld coordinate space, without taking into account transformations introduced by TransformGroups, so behavior desribed by hawkwind is correct.

I know this is not correct behavior and most probably will change in future. The original explanation from David on how this works can be found here: http://www.java-gaming.org/cgi-bin/JGNetForums/YaBB.cgi?board=xith3d;action=display;num=1063563461

Yuri

#4

[quote]Hi,

No, currently in Xith3D all the light positions and directions are defined in VWorld coordinate space, without taking into account transformations introduced by TransformGroups, so behavior desribed by hawkwind is correct.

I know this is not correct behavior and most probably will change in future.
[/quote]
Thanks Yuri for the clarification + explanation.

I use lights in your way (you’ve already answered that question some time ago) but illustrate the point light with a sphere which I move via transformgroup. Now I messed up them quoting from memory… (Getting older and forgetfully…)

#5

I have posted this as an FAQ: http://xith.org/tiki-view_faq.php?faqId=1#q16

I welcome everyone to suggest questions in tiki - I can then easily approve them and they become part of the faq.

Will.