mirror of
https://github.com/irmen/prog8.git
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Irmen de Jong
093be9f2dd
this means that all of the syslib.p8 library files no longer contain all those stack related asmsubs
114 lines
3.2 KiB
Lua
114 lines
3.2 KiB
Lua
%import graphics
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%import math
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%zeropage basicsafe
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%option no_sysinit
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main {
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uword terrain = memory("terrain", 320, 0)
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sub start() {
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graphics.enable_bitmap_mode()
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; sky
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graphics.clear_screen(7,6)
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; sun and clouds
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graphics.disc(240, 50, 34)
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graphics.colors(15,1)
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graphics.filled_oval(60, 50, 40, 16)
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graphics.colors(14,14)
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graphics.filled_oval(100, 60, 55, 22)
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graphics.colors(1,1)
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graphics.filled_oval(140, 40, 50, 20)
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graphics.filled_oval(180, 55, 60, 12)
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; cliffs
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start_terrain((math.rnd() % 100) + 50, (math.rnd() % 100) + 50)
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ubyte smoothness = 8
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ubyte extremes = 56
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recursive_midpoint(0, 319, extremes)
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draw(15)
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; mountains
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start_terrain((math.rnd() % 60) + 100, (math.rnd() % 60) + 100)
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smoothness = 6
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extremes = 50
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recursive_midpoint(0, 319, extremes)
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draw(12)
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; woods
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start_terrain((math.rnd() % 40) + 160, (math.rnd() % 40) + 160)
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smoothness = 5
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extremes = 35
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recursive_midpoint(0, 319, extremes)
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draw(9)
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; grasslands
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start_terrain((math.rnd() % 30) + 200, (math.rnd() % 30) + 200)
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smoothness = 4
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extremes = 21
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recursive_midpoint(0, 319, extremes)
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draw(5)
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; end.
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sub start_terrain(ubyte startheight, ubyte endheight) {
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terrain[0] = startheight
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terrain[319] = endheight
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interpolate(0, 319)
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}
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sub recursive_midpoint(uword s, uword e, ubyte displacement) {
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if displacement==0 or displacement>extremes
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return
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uword @zp half = s + (e-s) / 2
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if half!=s and half!=e {
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; displace the terrain
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uword t = terrain[half]
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ubyte d = math.rnd() % displacement
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if math.rnd() & 1 == 1
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t += d
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else
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t -= d
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terrain[half] = clamp(lsb(t), 10, 230)
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interpolate(s, half)
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interpolate(half, e)
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; recurse
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pushw(e)
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pushw(half)
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push(displacement)
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recursive_midpoint(s, half, displacement-smoothness)
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displacement = pop()
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half = popw()
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e = popw()
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recursive_midpoint(half, e, displacement-smoothness)
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}
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}
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}
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sub interpolate(uword start, uword end) {
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; linear interpolate the terrain heights between positions start and end.
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word ts = terrain[start]
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word te = terrain[end]
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alias istep = cx16.r0s
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alias ivalue = cx16.r1s
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istep = (te-ts) * 128 / (end-start)
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ivalue = ts * 128
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while start<=end {
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terrain[start] = msb(ivalue<<1)
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start++
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ivalue += istep
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}
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}
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sub draw(ubyte color) {
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; draw the terrain in the given color.
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graphics.colors(color, color)
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for cx16.r0 in 0 to 319 {
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graphics.line(cx16.r0, terrain[cx16.r0], cx16.r0, 239)
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}
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}
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}
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