Apple-2-SW/prog8
1
0
Fork 0
mirror of https://github.com/irmen/prog8.git synced 2025-01-12 04:30:03 +00:00
Code Issues Projects Releases Wiki Activity

changed to fixed point math to always generate bars of 32 lines height

Browse Source
This commit is contained in:
Irmen de Jong 2021-09-28 22:54:58 +02:00
parent 2cb1560bbd
commit 8388adcd1d
1 changed files with 68 additions and 78 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

146
examples/cx16/colorbars.p8
View File

@ -14,10 +14,11 @@ main {
ubyte yy
for yy in 0 to 239
gfx2.horizontal_line(0, yy, 320, yy & 63)
gfx2.horizontal_line(0, yy, 320, yy & 31)
repeat {
colors.random_bar()
colors.random_half_bar()
colors.mirror_bar()
colors.set_palette()
repeat 20
sys.waitvsync()
@ -30,96 +31,85 @@ main {
}
colors {
ubyte cr
ubyte cg
ubyte cb
ubyte[48+16] reds
ubyte[48+16] greens
ubyte[48+16] blues
ubyte target_red
ubyte target_green
ubyte target_blue
ubyte[32] reds
ubyte[32] greens
ubyte[32] blues
ubyte bar_size
sub random_rgb12() {
do {
uword rr = rndw()
cr = msb(rr) & 15
cg = lsb(rr)
cb = cg & 15
cg >>= 4
} until cr+cg+cb >= 12
target_red = msb(rr) & 15
target_green = lsb(rr)
target_blue = target_green & 15
target_green >>= 4
} until target_red+target_green+target_blue >= 12
}
sub random_bar() {
; fade black -> color then fade color -> white
random_rgb12()
ubyte r=0
ubyte g=0
ubyte b=0
ubyte different
bar_size = 0
sub mirror_bar() {
; mirror the top half bar into the bottom half
ubyte ix=14
ubyte mix=16
do {
reds[mix] = reds[ix]
greens[mix] = greens[ix]
blues[mix] = blues[ix]
mix++
ix--
} until ix==255
reds[mix] = 0
greens[mix] = 0
blues[mix] = 0
}
repeat {
different = false
if r != cr {
different = true
r++
sub random_half_bar() {
; fade black -> color then fade color -> white
; gradient calculations in 8.8 bits fixed-point
; could theoretically be 4.12 bits for even more fractional accuracy
random_rgb12()
uword r = $000
uword g = $000
uword b = $000
uword dr = target_red
uword dg = target_green
uword db = target_blue
ubyte ix = 1
; gradient from black to halfway color
reds[0] = 0
greens[0] = 0
blues[0] = 0
dr <<= 5
dg <<= 5
db <<= 5
continue_gradient()
; gradient from halfway color to white
dr = (($f00 - r) >> 3) - 1
dg = (($f00 - g) >> 3) - 1
db = (($f00 - b) >> 3) - 1
continue_gradient()
return
sub continue_gradient() {
repeat 8 {
reds[ix] = msb(r)
greens[ix] = msb(g)
blues[ix] = msb(b)
r += dr
g += dg
b += db
ix++
}
if g != cg {
different = true
g++
}
if b != cb {
different = true
b++
}
if not different
break
reds[bar_size] = r
greens[bar_size] = g
blues[bar_size] = b
bar_size++
}
repeat {
different = false
if r != 15 {
different = true
r++
}
if g != 15 {
different = true
g++
}
if b != 15 {
different = true
b++
}
if not different
break
reds[bar_size] = r
greens[bar_size] = g
blues[bar_size] = b
bar_size++
}
; mirror bottom half from top half
ubyte mi = bar_size-1
repeat mi {
reds[bar_size] = reds[mi]
greens[bar_size] = greens[mi]
blues[bar_size] = blues[mi]
bar_size++
mi--
}
; make rest of bar black (bars are not always the same length using the simplistic algorithm above...)
while bar_size != 48+16 {
reds[bar_size] = $0
greens[bar_size] = $0
blues[bar_size] = $0
bar_size++
}
}
sub set_palette() {
ubyte ix
for ix in 0 to 48+15 {
for ix in 0 to 31 {
uword color = mkword(reds[ix], (greens[ix] << 4) | blues[ix] )
palette.set_color(ix, color)
}