Re: Roland's point size patch. Was: Re: [Bug 702] Radeon only supports a maximum point size of 1.0.

[Roland S. <rsc...@hi...>]

Philipp Klaus Krause wrote:
> Roland found out how to do bigger aliased points on r200 hardware a long
> time ago. AFAIK the patch was never applied since people failed to see
> it's importance.
> 
> 3D modellers use points to mark the currently selected vertices. A
> maximum point size of 1 means they are invisible with today's screen
> resolutions. This makes the r200 DRI driver useless for 3D modelling
> with those applications. Bigger point sizes are really necessary!
> 
> Roland's patch supported only aliased points, but since the maximum
> point sizes for aliased and antialised points can be different that
> would never cause a software fallback. I know that the popular free
> wings3d modeller uses only aliased points and think that it's the same
> with other 3d modellers.
Ok here's a patch. It needs a semi-recent drm. It is downright trivial, 
all points with size != 1.0 are simply rendered with the point sprite 
primitive. Up to size 2047.0 - that should be enough for everyone :-).
No point parameters or point sprites for now.
In fact it would be possible to do it without a new drm - since the 
hardware can clamp the point size. But I'm not too sure if it's a good 
idea to do the point size calculation with unconfigured inputs and then 
simply clamping the result.
One thing which is slightly confusing though is the register name, 
R200_SE_TCL_POINT_SPRITE_CNTL seems to imply this only works when using 
hw tcl. Now I don't doubt the point attenuation calculation will only 
work when using hw tcl, but I can't see a reason why the selection bit 
would not work with sw tcl (and I'd hope the point sprite tex coord 
generation would work with sw tcl too, otherwise there'd be a big 
problem when for some other reason there's a tcl fallback - it's 
impossible to manually attach 4 sets of tex coords to a single vertex I 
guess). Works fine for me with tcl_mode=0, but I don't have hardware 
which doesn't have tcl hardware (only IGP 9100 family doesn't have tcl). 
If it doesn't work there we'd need to submit the point size as a vertex 
parameter (which has the nice side-effect of getting ARB_point_parameter 
for free for the sw tcl case).

Roland