Quote: "I think you can do that (along with other drawing operations) by using set current bitmap -cameraId.
Notice that the bitmap number should be the negative camera id."
Exactly.
Here's a simple demo:
set display mode desktop width(), desktop height(), 32
sync on : sync rate 60 : sync
autocam off
position camera 0, 80, -200
point camera 0, 0, 0
color backdrop 0
make camera 1
set camera to image 1, 11, 128, 128
position camera 1, 0, 500, 0
point camera 0, 0, 0
color backdrop 1, rgb(0, 64, 0)
` make some scene objects
for objID = 1 to 5
make object sphere objID, 50
position object objID, rnd(300)-150, 0, rnd(300)-150
next objID
` make an object to receive the camera tagret
make object cube 100, 100
position object 100, -100, 0, 0
texture object 100, 11
repeat
set current bitmap -1 ` the next three lines output to the target of camera 1, i.e. image 11
cls rgb(32,128,16)
ink rgb(255,0,0), 0
text 20, 20, "Hi there!"
set current bitmap 0 ` return rendering to the screen
` do something exciting in the scene ...
yrotate object 100, object angle y(100)+1
sync mask 1 ` just render camera 0 in the usual way
sync
until spacekey()
end