mirror of
https://github.com/irmen/prog8.git
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118 lines
2.6 KiB
Lua
118 lines
2.6 KiB
Lua
%import gfx2
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%import palette
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%import textio
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; TODO WORK IN PROGRESS...
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; want to make Amiga 'copper' bars color cycling effects
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main {
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sub start() {
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palette.set_all_black()
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gfx2.screen_mode(4)
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ubyte yy
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for yy in 0 to 239
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gfx2.horizontal_line(0, yy, 320, yy & 31)
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repeat {
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colors.random_half_bar()
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colors.mirror_bar()
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colors.set_palette()
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repeat 20
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sys.waitvsync()
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}
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repeat {
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}
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}
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}
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colors {
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ubyte target_red
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ubyte target_green
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ubyte target_blue
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ubyte[32] reds
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ubyte[32] greens
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ubyte[32] blues
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ubyte bar_size
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sub random_rgb12() {
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do {
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uword rr = rndw()
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target_red = msb(rr) & 15
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target_green = lsb(rr)
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target_blue = target_green & 15
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target_green >>= 4
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} until target_red+target_green+target_blue >= 12
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}
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sub mirror_bar() {
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; mirror the top half bar into the bottom half
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ubyte ix=14
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ubyte mix=16
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do {
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reds[mix] = reds[ix]
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greens[mix] = greens[ix]
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blues[mix] = blues[ix]
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mix++
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ix--
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} until ix==255
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reds[mix] = 0
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greens[mix] = 0
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blues[mix] = 0
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}
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sub random_half_bar() {
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; fade black -> color then fade color -> white
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; gradient calculations in 8.8 bits fixed-point
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; could theoretically be 4.12 bits for even more fractional accuracy
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random_rgb12()
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uword r = $000
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uword g = $000
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uword b = $000
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uword dr = target_red
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uword dg = target_green
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uword db = target_blue
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ubyte ix = 1
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; gradient from black to halfway color
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reds[0] = 0
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greens[0] = 0
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blues[0] = 0
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dr <<= 5
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dg <<= 5
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db <<= 5
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continue_gradient()
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; gradient from halfway color to white
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dr = (($f00 - r) >> 3) - 1
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dg = (($f00 - g) >> 3) - 1
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db = (($f00 - b) >> 3) - 1
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continue_gradient()
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return
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sub continue_gradient() {
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repeat 8 {
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reds[ix] = msb(r)
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greens[ix] = msb(g)
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blues[ix] = msb(b)
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r += dr
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g += dg
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b += db
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ix++
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}
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}
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}
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sub set_palette() {
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ubyte ix
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for ix in 0 to 31 {
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uword color = mkword(reds[ix], (greens[ix] << 4) | blues[ix] )
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palette.set_color(ix, color)
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}
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}
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}
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