Point sprites ?

Engines, Libraries and Tools Xith3D Forums
#1

Hello,

I have looked through the code of Xith3D and there is no support for point sprites (GL_ARB_point_sprite).

What is the best place to implement this ? Probably in the PointAttributes class. This would add no new class and all needed information is available (only the texture and vertex coordinates are needed).

The only question is when must point sprites be rendered - probably in the transparent rendering pass. This can be done by simply setting a TransparencyAttributes with BLENDED and a value of 0.

Is someone already working on this ?

#2

[quote]Hello,

I have looked through the code of Xith3D and there is no support for point sprites (GL_ARB_point_sprite).

What is the best place to implement this ? Probably in the PointAttributes class. This would add no new class and all needed information is available (only the texture and vertex coordinates are needed).

The only question is when must point sprites be rendered - probably in the transparent rendering pass. This can be done by simply setting a TransparencyAttributes with BLENDED and a value of 0.

Is someone already working on this ?
[/quote]
Nobody is working on this, it’s all yours ;D

Have you seen my Render Pipeline diagram? It might help with your understanding of Xith3D. http://xith.org/RenderPipeline

Good stuff :slight_smile:

Will.

#3

Hi Matthias,

I have tested point sprites in my private build of Xith3D, and I implemented it as an attribute in PointAttributes.

For me, point sprites should be rendered on the pass following the policy of Xith3D (opaque sprites on opaque pass, etc.). This behavior anyway determined by other attributes (transaprency, texture, etc.). Point sprites are only way of texturizing the shape (either normal texture mapping or texture-per-vertex)

Note that NV_ and ARB_ point sprite extensions should be supported (of course, this behavior is prefered).

Hopefully I will get time to publish some of my private changes to public CVS during next 1-3 weeks, because of some new work involving coding for Xith3D is coming.

Yuri

#4

Hello,

It’s good to know that someone has already solved this. Did you use it for a particle system ? How is the performance of constantly updating the vertices of the PointArray ?

I think it should be possible without relaing on the NV_ extension. It is only needed for the mode POINT_SPRITE_R_MODE_NV.

See http://oss.sgi.com/projects/ogl-sample/registry/ARB/point_sprite.txt for future details on the dependencies on the NV_ extension.

Ciao Matthias Mann