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https://github.com/irmen/prog8.git
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117 lines
3.8 KiB
Lua
117 lines
3.8 KiB
Lua
; Simple sprite multiplexer.
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; This is just a sprite duplicator routine that displays the 8 hardware sprites multiple times in rows,
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; it does not do any complicated sprite Y manipulation/multiplexing.
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; No assembly code is used.
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%import syslib
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%zeropage basicsafe
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%option no_sysinit
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main {
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sub start() {
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ubyte i
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for i in 0 to 7 {
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c64.set_sprite_ptr(i, &sprites.balloonsprite) ; alternatively, set directly: c64.SPRPTR[i] = $0a00 / 64
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}
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sprites.set_sprites_X(0)
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sprites.set_sprites_Y(sprites.sprites_Y_start)
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c64.SPCOL[5] = 8 ; change blue balloon to different color
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c64.SPENA = 255 ; enable all sprites
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irq.first_sprite_X = 0
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irq.sprites_Y = sprites.sprites_Y_start
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sys.set_rasterirq(&irq.multiplexer, irq.sprites_Y+1)
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; exit program back to basic, balloons will keep flying :-)
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}
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}
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irq {
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uword first_sprite_X
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ubyte sprites_Y
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; Here is the actual multiplexing routine.
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; it's a raster irq just after the start of the sprite,
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; that updates the Y position of all the sprits,
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; and registers a new raster irq for that next row of sprites.
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; If the bottom of the screen is reached, it resets the X position of the sprites as well,
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; and moves the sprites back to the top of the screen.
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sub multiplexer() -> bool {
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c64.EXTCOL++
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sprites_Y += 24
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bool system_irq = false
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if sprites_Y > (255-24-1) {
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cx16.r2 = c64.RASTER + 23
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sprites_Y = sprites.sprites_Y_start
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first_sprite_X++
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if first_sprite_X >= 340
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first_sprite_X = 0
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sprites.set_sprites_Y(sprites_Y)
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while c64.RASTER != cx16.r2 {
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; wait until raster line after sprites have been fully drawn (at least 24 lines down)
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}
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sprites.set_sprites_X(first_sprite_X) ; we can now update the X positions without risk of sprite tearing
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system_irq = true
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} else {
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; only set the new Y positions. But it's possible to change other attributes as well ofcourse (colors, x-position, data)
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; but raster timing is critical for that if you want to avoid tearing and glitches. Can probably not be done here at this raster position...
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sprites.set_sprites_Y(sprites_Y)
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c64.SPXY[0]++
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}
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sys.set_rasterline(sprites_Y+1)
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c64.EXTCOL--
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return system_irq
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}
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}
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sprites {
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const ubyte sprites_Y_start = 55
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sub set_sprites_Y(ubyte y) {
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for cx16.r0L in 1 to 15 step 2 {
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c64.SPXY[cx16.r0L] = y
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}
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}
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sub set_sprites_X(uword x) {
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for cx16.r0L in 0 to 14 step 2 {
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x += 20
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if x >= 340
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x -= 340
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c64.SPXY[cx16.r0L] = lsb(x)
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cx16.r1L = msb(x)>>1
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ror(c64.MSIGX) ; rotate that MSB bit of the sprite X position into the MSB sprite X register for each sprite
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}
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}
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ubyte[] @align64 balloonsprite = [
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%00000000,%01111111,%00000000,
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%00000001,%11111111,%11000000,
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%00000011,%11111111,%11100000,
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%00000011,%11100011,%11100000,
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%00000111,%11011100,%11110000,
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%00000111,%11011101,%11110000,
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%00000111,%11011100,%11110000,
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%00000011,%11100011,%11100000,
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%00000011,%11111111,%11100000,
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%00000011,%11111111,%11100000,
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%00000010,%11111111,%10100000,
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%00000001,%01111111,%01000000,
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%00000001,%00111110,%01000000,
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%00000000,%10011100,%10000000,
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%00000000,%10011100,%10000000,
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%00000000,%01001001,%00000000,
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%00000000,%01001001,%00000000,
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%00000000,%00111110,%00000000,
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%00000000,%00111110,%00000000,
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%00000000,%00111110,%00000000,
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%00000000,%00011100,%00000000
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]
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}
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