Simon Bennett (simonb++at++wormald.com.au)
Tue, 7 Mar 1995 18:24:19 +1000 (EST)
"pfLPointColor sets the color of light point index in lpoint to clr. The
actual color displayed depends on light point direction, shape, position,
and fog. clr specifies red, green, blue and alpha in the range 0.0 to
1.0. A pfLightPoint is turned off with an alpha of 0.0 since it will be rendered
as completely transparent. "
So basically the only way to "delete" lightpoints from an existing
lightpoint node is to set the alpha values of the unwanted nodes to
0.0. I gather that there's no undocumented pfSetNumLPoints() call or
pfDeleteLPoint() calls hanging around?
If this is so, does Performer send these complete transparent lightpoints to
the geometry pipeline or not? For example, say I've got 1000 lightpoints and
that depending on a number of criteria I'd like to display some of them as 1
pixel and some of them as 3 pixels. If I setup 2 lightpoint nodes each with
a 1000 point capability, but one with a pfLPointSize of 1.0 and the other
with a pfLPointSize of 3.0 - to "move" points between the two nodes, the
alpha values are changed from 1.0 (exists) to 0.0 (doesn't exist). If I
always render the whole 1000 points in the scene and evenly balance the
points between the two nodes (i.e. the same point position never appears
in both nodes) how many points are sent to the pipeline? 1000 or 2000?
For simplicity of the example I've forgone the usual spacial partitioning
issues.
Also, as it's not documented anywhere, maybe somebody at Multigen or SGI
can answer this... with the PFLP_OVERALL colour mode can you still
reliably turn off individual points by tweaking the alpha value? Or do
you have to re-create a pfLightpoint node that doesn't use this colour
mode?
Much thanx
+--------------------------------------------------------------------------------+
Simon Bennett simonb++at++wormald.com.au
Wormald Technology Advanced Systems Engineering Ph: +61 2 981 0611 (x512)
Computer Terms: hardware - the part of a computer system that one can kick
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