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-- snekmaze ii
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-- by arborelia
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function _init()
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-- tiles to move per frame
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-- don't make this more than 1
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fstep = 1/6
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-- step counter
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-- it can overflow, that's fine
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step = 0
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trailpos = 0
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-- number of frames in trail
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ntrail = 20
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-- size of the grid (even)
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gsize = 10
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-- where to go in the tile
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enterx = -1
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entery = 0
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exitx = 0
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exity = -1
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-- which tile we're in
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tx = 0
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ty = 0
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grid = {}
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local x,y,i
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for x=0,gsize-1 do
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grid[x] = {}
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for y=0,gsize-1 do
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grid[x][y] = 0
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end
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end
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-- size of each tile
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tsize = flr(128/gsize)
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border = (128 - tsize*gsize)/2
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camera(-border,-border)
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-- trail of prev. locations
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trail = {}
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trail.x = {}
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trail.y = {}
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for i=0,ntrail-1 do
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trail.x[i] = 0
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trail.y[i] = 0.5
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end
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-- draw starting grid
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cls(7)
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for x=0,gsize-1 do
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for y=0,gsize-1 do
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draw_tile(x,y)
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end
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end
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flip_tile()
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end
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-- run updates at 60 fps
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function _update60()
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-- previous step
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p_step = step
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step += fstep
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if flr(step) != flr(p_step) then
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enter_tile()
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end
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trailpos = (trailpos + 1) % ntrail
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update_trail()
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end
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function enter_tile()
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old_fx = fx
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old_fy = fy
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enterx = -exitx
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entery = -exity
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tx = (tx+exitx) % gsize
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ty = (ty+exity) % gsize
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local way = grid[tx][ty]
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if enterx == 0 then
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exity = 0
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exitx = entery * (1-(2*way))
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else
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exitx = 0
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exity = enterx * (1-(2*way))
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end
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flip_tile()
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draw_tile(old_fx, old_fy)
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end
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function flip_tile()
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-- which tile's being flipped
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-- (global)
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fx = (tx + gsize/2) % gsize
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fy = (ty + gsize/2) % gsize
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grid[fx][fy] = 1-grid[fx][fy]
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end
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function update_trail()
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local half=tsize/2
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local frac = step - flr(step)
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local unfrac = 1-frac
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local posx = (
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tsize*tx + half
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+ half * unfrac * enterx
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+ half * frac * exitx
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)
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local posy = (
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tsize*ty + half
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+ half * unfrac * entery
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+ half * frac * exity
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)
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trail.x[trailpos] = posx
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trail.y[trailpos] = posy
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end
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function _draw()
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local p = trailpos
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local n = ntrail
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draw_tile(fx,fy)
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spot(
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trail.x[(p+1) % n],
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trail.y[(p+1) % n],
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7
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)
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spot(
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trail.x[(p+2) % n],
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trail.y[(p+2) % n],
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7
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)
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spot(
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trail.x[(p-1) % n],
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trail.y[(p-1) % n],
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3
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)
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spot(
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trail.x[p],
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trail.y[p],
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3
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)
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-- debug()
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end
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function spot(x,y,c)
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local size=flr(tsize/8)
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if size < 2 then
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rectfill(x,y,x+1,y+1,c)
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else
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circfill(x,y,tsize/8,c)
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end
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end
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function draw_tile(x,y)
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local xin,yin,xout,yout,way,c
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rectfill(
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x*tsize, y*tsize,
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(x+1)*tsize,
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(y+1)*tsize,
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7
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)
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way=grid[x][y]
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-- where the gate goes, in
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-- tile coordinates
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xin=x
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xout=(x+1)
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yin=(y+(1-way))
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yout=(y+way)
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if way==0 then c=12 else c=14 end
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-- is it the flipping tile?
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if x==fx and y==fy then
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frac = step - flr(step)
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if way==1 then
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yin=(y+(1-frac))
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yout=(y+frac)
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else
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xin=(x+(1-frac))
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xout=(x+frac)
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end
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-- change line color
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c=1
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end
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if tsize > 8 then
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-- draw a thick line
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for dx=-1,1 do
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for dy=-1,1 do
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local pxin = xin*tsize + dx
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local pyin = yin*tsize + dy
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local pxout = xout*tsize+dx
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local pyout = yout*tsize+dy
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pxin=mid(x*tsize, (x+1)*tsize, pxin)
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pyin=mid(y*tsize, (y+1)*tsize, pyin)
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pxout=mid(x*tsize,(x+1)*tsize, pxout)
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pyout=mid(y*tsize,(y+1)*tsize, pyout)
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line(pxin,pyin,pxout,pyout,c)
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end
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end
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else
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line(
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xin*tsize,yin*tsize,
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xout*tsize,yout*tsize,c
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)
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end
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draw_grid()
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end
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function draw_grid()
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local x,y
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for x=0,gsize-1 do
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for y=0,gsize-1 do
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px = x * tsize
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py = y * tsize
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if tsize > 8 then
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rectfill(px-1,py-1,px+1,py+1,6)
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else
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pset(px,py,6)
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end
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end
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end
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end
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function debug()
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rectfill(0,0,128,6,0)
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print(step,0,0,7)
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end
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