[GEM-dev] "blend"-messages

[IOhannes m zmoelnig]

hi

i just noticed, that jamie has committed changes to the "cube"-Geos, to 
allow a [blend 1/0( message.

however, to avoid restarting this and to save everyone a lot of 
programming time, i would suggest:
1) using inheritance rather than putting the same piece of code in each Geo.
2) (more important): why not use [alpha] and [polygon_smooth] ?
i think this has been discussed.
[alpha] certainly needs more attention to make the 
blending-style-setting more consistent.

i don't think, that there is any performance-issue in this, and it could 
save us all (jamie) a lot of time...

mfg.as.rd
IOhannes

ps:here is my last email regarding this, from 25/02/03:

chris clepper wrote:

 >> and another two changes:
 >>
 >> 1. [alpha]
 >> now you can set the blending-function
 >> 0..GL_ONE_MINUS_SRC_ALPHA that's the (old) default
 >> 1..GL_ONE (as would be enabled by the "blend" message to various 
objects.
 >
 >

 > perhaps we should add some of the other options for glBlend and allow 
both the source and destination to be changed.


yes definitely.
it was just done very quickly.

 >
 >> 2. [polygon_smooth]
 >> enables polygon smoothing
 >>
 >
 > the only difference i found is that [polygon_smooth] sets blending 
for the entire render chain it's attached to while the "blend" method 
would actually work on individual objects in the same chain.  it's 
probably not a big deal, and maybe not even a big feature to warrant 
keeping "blend".  it's definitely easier to do the [polygon_smooth] 
rather than add glBlend to each Geo.


it enables aa'ing for everything that comes below the [polygon_smoothing].
Maybe we should just add a another state that disables aa'ing:
suggestion:
1 .. enable smoothing
0 .. disbale smoothing
-1 .. leave unchanged


 >> i think [polygon_smooth] is a bad name. but which one would be better ?
 >
 > still no suggestions for the name...  maybe wrapping [alpha], [color]

well, yes it is not that bad. (at least better than [pix_a_2grey])

 > and [polygon_smooth] up in an abstraction called [geo_blend] would be 
something to try?

;-)

mfg.ads.r
IOhannes