mirror of
https://github.com/irmen/prog8.git
synced 2024-08-18 23:29:32 +00:00
191 lines
4.9 KiB
Lua
191 lines
4.9 KiB
Lua
%import textio
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; Amiga 'copper' bars color cycling effect
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main {
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sub start() {
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; make palette color 1 black so we can print black letters over the background color 0
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void cx16.screen_set_mode(0)
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cx16.vpoke(1, $fa02, $0)
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cx16.vpoke(1, $fa03, $0)
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txt.color(1)
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txt.plot(13,12)
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txt.print("amiga-inspired")
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txt.plot(10,14)
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txt.print("raster blinds effect")
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txt.plot(12,16)
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txt.print("random gradients")
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irq.make_new_gradient()
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cx16.set_rasterirq(&irq.irqhandler, irq.top_scanline)
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repeat {
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}
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}
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}
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irq {
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const ubyte top_scanline = 0
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ubyte blinds_start_ix = 0
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ubyte color_ix = 0
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uword next_irq_line = top_scanline
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ubyte shift_counter = 0
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ubyte[32+32+16] blinds_lines_reds
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ubyte[32+32+16] blinds_lines_greens
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ubyte[32+32+16] blinds_lines_blues
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sub irqhandler() {
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set_scanline_color(color_ix)
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color_ix++
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next_irq_line += 2 ; code needs 2 scanlines per color transition
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if next_irq_line == 480 {
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; start over at top
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next_irq_line = top_scanline
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blinds_start_ix = 0
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color_ix = 0
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shift_counter++
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if shift_counter == 32+32+32 {
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make_new_gradient()
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shift_counter = 0
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} else if shift_counter & 1 {
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shift_gradient()
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}
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} else if next_irq_line & 15 == 0 {
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; start next blinds
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blinds_start_ix++
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color_ix = blinds_start_ix
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}
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cx16.set_rasterline(next_irq_line)
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}
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sub make_new_gradient() {
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colors.random_half_bar()
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colors.mirror_bar()
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sys.memcopy(colors.reds, &blinds_lines_reds+32+16, len(colors.reds))
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sys.memcopy(colors.greens, &blinds_lines_greens+32+16, len(colors.greens))
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sys.memcopy(colors.blues, &blinds_lines_blues+32+16, len(colors.blues))
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}
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sub shift_gradient() {
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sys.memcopy(&blinds_lines_reds+1, blinds_lines_reds, len(blinds_lines_reds)-1)
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sys.memcopy(&blinds_lines_greens+1, blinds_lines_greens, len(blinds_lines_greens)-1)
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sys.memcopy(&blinds_lines_blues+1, blinds_lines_blues, len(blinds_lines_blues)-1)
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}
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asmsub set_scanline_color(ubyte color_ix @Y) {
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; uword color = mkword(reds[ix], (greens[ix] << 4) | blues[ix] )
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%asm {{
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lda blinds_lines_reds,y
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pha
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lda blinds_lines_greens,y
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asl a
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asl a
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asl a
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asl a
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ora blinds_lines_blues,y
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tay
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stz cx16.VERA_CTRL
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lda #%00010001
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sta cx16.VERA_ADDR_H
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lda #$fa
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sta cx16.VERA_ADDR_M
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; lda #$02
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; sta cx16.VERA_ADDR_L
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stz cx16.VERA_ADDR_L
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sty cx16.VERA_DATA0 ; gb
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pla
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sta cx16.VERA_DATA0 ; r
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stz cx16.VERA_ADDR_H
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rts
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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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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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}
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