I believe you can use
Sync Mask for this:
fog on
sync mask 2^0 : fastsync
fog off
sync mask 2^1 : fastsync
Example:
sync on
sync rate 60
autocam off
cls rgb(85, 85, 85)
for xy = 0 to 1
box xy*16,xy*16,(xy*16)+16,(xy*16)+16,rgb(76, 76, 76)
next
get image 1,0,0,32,32,1 : cls
make matrix 1,1024,1024,128,128
position matrix 1,-512,-2,-512
prepare matrix texture 1,1,1,1
make camera 1
backdrop on 0
backdrop on 1
color backdrop 0
color backdrop 1,0
set camera view 0,0,0,screen width()/2,screen height()
set camera view 1,screen width()/2,0,screen width(),screen height()
set camera aspect 0,((screen width()/2.0) / screen height())
set camera aspect 1,((screen width()/2.0) / screen height())
do
// render cameras
fog on
fog distance 128
fog color rgb(0, 255, 0)
sync mask 2^0 : fastsync
fog off
sync mask 2^1 : fastsync
sync
loop
"Get in the Van!" - Van B
