見栄えの為gmode 4を使っていますが、こんな感じですか?
screen 1, 640, 480 : cls 4
color 255, 0, 0 : circle 0, 0, 80, 80
color 0, 255, 0 : circle 80, 0, 160, 80
color 0, 0, 255 : circle 160, 0, 240, 80
color 255, 255, 255 : circle 240, 0, 320, 80
celdiv 1, 80, 80, 40, 40
cno = 0, 1, 2
cx = 100, 320, 540
cy = 240, 240, 240
bl = 0, 0, 0
flg = 0
bl(0) = 1
gsel 0, 1
*main
redraw 0
color 0, 0, 0 : boxf
repeat 3
if bl(cnt) >= 255 {
gmode 4, , , 255
color 0, 0, 0
pos cx(cnt), cy(cnt)
celput 1, 3
} else {
if bl(cnt) ! 0 {
gmode 4, , , bl(cnt)
color 0, 0, 0
pos cx(cnt), cy(cnt)
celput 1, cno(cnt)
bl(cnt) = limit(bl(cnt) + 1, 0, 255)
}
}
loop
if flg < 3 {
if bl(flg) = 128 {
flg + 1
bl(flg) = 1
}
}
redraw 1
title "ブレンド率=" + bl(0) + " " + bl(1) + " " + bl(2)
await 10
goto *main