EntityFX

Blitz3D Forums/Blitz3D Beginners Area/EntityFX

BLaBZ

(Posted 2008) [#1]

If someone could explain this to me..

EntityFX mesh,1+16

I dont understand how the flags work.
what does 1+16 mean?

16 isn't referenced in the command reference

Thanks!

tonyg

(Posted 2008) [#2]

From the doc...

entity - entity handle

fx -
0: nothing (default)
1: full-bright
2: use vertex colors instead of brush color
4: flatshaded
8: disable fog
16: disable backface culling
32: force alpha-blending

boomboom

(Posted 2008) [#3]

for the flags:

you have 3 options when using flags really. The example you gave is '16 + 1' which is the first way. This basically does a calculation and gives the result '17' being 16+1=17.

This means 'disable backface culling' + 'full-bright'

To get this same effect your 3 ways of doing it are:

EntityFX mesh,17

EntityFX mesh,1+16


;or predefining all the effects as readable variables.
Const FX_FullBright% = 1
Const FX_DisableBackface% = 16

EntityFX mesh, FX_DisableBackface + FX_FullBright

These all use the number '17' which is then what Blitz uses to work out the mixture of effects you want.

GfK	(Posted 2008) [#4]

I dont understand how the flags work.
what does 1+16 mean?

At the risk of sounding sarcastic, EntityFX mesh,1+16, is the same as EntityFX mesh,17. Although both are acceptable, its normally expressed as the former for clarity when re-reading your code.

Not sure which version of the documentation you're looking at but the section tonyg refers to has been there for as long as I can remember.

jfk EO-11110

(Posted 2008) [#5]

And let me mention, these are Bit Flags. Each bit may activate or deactivate something. It is ok to say 16+1, but by definition you should use boolean operators to control Bit Flags. So if you want to set certain bits in a variable, you'll use the OR command, sample:

settings%= 16 OR 1 OR 4 OR 512

and if you want to erase certain bits then you'll use AND NOT(value), where the NOT operator must be replaced by the ~ operator, because NOT does not work as it should IMHO eg:

settings%=settings% AND ~(16)

so this would set the bit number 5 (that represents the value 16) to Zero, no matter if it was aready Zero before, or if it was One.

Note: The common boolean command NOT will/should invert an integer variables bits. ~ is doing the same, but by convention NOT is classical syntax (but doesn't work in Blitz).

Wings

(Posted 2008) [#6]

1+16 = 4 letters :D

for anyone who dont know + is almoust same as a or.
as long as the bits done overlaps.

010010
+
101101
=
111111

010010
OR
101101
=
111111

so ressult is same.. but only cause the bitds dint overlap