kirby_run.lua

-- gumtree.lua
-- coordinates: x,y = ground; z = vertical

-- camera
local gt_cam={
	x=0,
	y=0,
	z=0,
	-- spin angle
	s=0,
	-- tilt angle
	t=1/8,
	-- scale (1 means 1:1)
	k=8,
	-- perspective (number > 0, or nil for orthographic)
	p=80,
}

-- buckets
local gt_mind=nil
local gt_maxd=nil
local gt_buckets={}

-- voxels
-- create a voxel object
function gt_voxel(x,y,z,w,c)
	return {x=x,y=y,z=z,w=w,c=c}
end

-- create a voxel object and draw it
function gt_draw_new_voxel(x,y,z,w,c)
	gt_draw_voxel({x=x,y=y,z=z,w=w,c=c})
end

-- draw a voxel object
function gt_draw_voxel(v)
	-- transform
	local cs=gt_cam.cs
	local ss=gt_cam.ss
	local ct=gt_cam.ct
	local st=gt_cam.st
	local k=gt_cam.k
	
	local x=v.x-gt_cam.x
	local y=v.y-gt_cam.y
	local z=v.z-gt_cam.z
	
	x,y=x*cs-y*ss,x*ss+y*cs

	-- depth
	local dz=(z*ct-y*st)*k
	
	-- perspective
	local p=gt_cam.p
	if p then
		if dz>=p then
			v.r=false
			return
		else
			k/=(1-dz/p)
		end
	end
	v.r=true

	-- save render position to object
	v.rx=x*k+64
	v.ry=(y*ct+z*st)*k+64
	v.rw=v.w*k
	
	-- save to bucket
	-- depth resolution is int, can multiply
	-- before flr() to increase resolution
	-- (more buckets, but may perform worse)
	local d=flr(dz)
	if gt_mind==nil then
		gt_mind=d
		gt_maxd=d
	else
		gt_mind=min(gt_mind,d)
		gt_maxd=max(gt_maxd,d)
	end
	local b=gt_buckets[d]
	if not b then
		b={}
		gt_buckets[d]=b
	end
	add(b,v)
end

-- main functions
-- call at the start of _update, after camera parameters have been set
function gt_start()
	gt_buckets={}
	gt_mind=nil
	gt_maxd=nil
	gt_cam.cs=cos(gt_cam.s)
	gt_cam.ss=sin(gt_cam.s)
	gt_cam.ct=cos(gt_cam.t)
	gt_cam.st=sin(gt_cam.t)
end

-- call at the end of _draw, after all draw calls have been made
function gt_end()
		if gt_mind then
		for d=gt_mind,gt_maxd do
			local b=gt_buckets[d]
			if b then
				for i=1,#b do
					local o=b[i]
					local x=o.rx
					local y=o.ry
					local w=o.rw
					rectfill(x-w,y-w,x+w,y+w,o.c)
					-- debug stuff
					-- draw voxel outline
					--rect(x-w,y-w,x+w,y+w,0)
					-- put a flip in it:
					--if n%20==0 then flip() end
				end
			end
		end
	end
end

-- gumtree_test.lua

-- create input handler to move camera
-- call in update (before gt_start)
function gt_test_cam()
	local ix,iy=0,0
	if(btn(0))ix-=1
	if(btn(1))ix+=1
	if(btn(2))iy-=1
	if(btn(3))iy+=1
	local s=-gt_cam.s
	local cs=cos(s)
	local ss=sin(s)
	local rix,riy=ix*cs-iy*ss,ix*ss+iy*cs
	
	if btn(4) and btn(5) then
		gt_cam.p+=ix
	elseif btn(4) then
		gt_cam.s-=ix/130
		gt_cam.t+=iy/130
		--cam.t=mid(0,cam.q,1/4)
	elseif btn(5) then
		gt_cam.k+=ix/4
		gt_cam.z-=iy/8
	else
		gt_cam.x+=rix/8
		gt_cam.y+=riy/8
	end
end

-- kirby.p8

function lerp(t,a,b)
	return a+(b-a)*t
end

function rot(x,y,a)
	return x*cos(a)-y*sin(a),x*sin(a)+y*cos(a)
end

function _draw()
	cls(7)
	
	--gt_test_cam()
	gt_cam.t=0.23
	gt_cam.s=0.75+sin(t()/8)*0.09
	gt_cam.k=6
	gt_cam.p=100
	
	gt_start()
	
	kirby()
	
	gt_end()
	
	--?stat(1),1,1,8
end

function rnd2(a,b)
	return a+rnd(b-a)
end

function sphc(r,a,b)
	return 
		r*cos(a)*cos(b),
		r*sin(a)*cos(b),
		-r*sin(b)
end

function sph(r,a,b,w,c)
	gt_draw_new_voxel(
		r*cos(a)*cos(b),
		r*sin(a)*cos(b),
		-r*sin(b),
		w,
		c
	)
end

dusts={}
frame=0
fillp(0x5a5a)

--debug: slow animation rate
--function t() return frame/200 end

function kirby()
 --body radius
	local r=4
	--twist amount
	local ta=sin(t()*3+0.25)*0.012
	--vertical bobbing offset
	local dz=sin(t()*6+0.6)*0.19
	
	--dust
	if frame%2==0 then
		local dust=gt_voxel(
			-2.5,
			rnd2(-3.2,3.2),
			-5,
			0.7,
			6+7*16
		)
		add(dusts,dust)
	end
	
	for dust in all(dusts) do
		gt_draw_voxel(dust)
		dust.w*=0.9
		dust.x-=1.4
		if dust.w<0.05 then
			del(dusts,dust)
		end
	end
	
	--body
	for v=-0.98,0.98,0.1 do
		local s=sqrt(1-v*v)
		for a=0,1,0.1-s*0.05 do
			a-=ta/3
			local x2=v*r
			local y2=s*cos(a)*r
			local z2=s*sin(a)*r+dz
			gt_draw_new_voxel(
				x2,
				y2,
				z2,
				0.55,
				14*17
			)
		end
	end
	
	for i=-1,1,2 do
		local ra=sin(t()*3+i/4)*0.13
		local rb=i*ra*0.6
		
		--eyes and blush
		function face(r,a,b,w,c)
			local x,y,z=sphc(r,a,b)
			x,y=rot(x,y,ta)
			z+=dz
			gt_draw_new_voxel(x,y,z,w,c)
		end
		a=i/28
		for j=0,1,0.1 do
			--local j2=(1+j)/2
			--local r1=sqrt(1.2-j*j)
			--local r2=sqrt(max(0.33-(j-0.27)^2))*1.6
			--local lr=sqrt(2-((j-.75)*7)^2)
			--local kp=sqrt(1.1-(j*2-1)^2)*0.01
			--for p=-1,1,.25 do
			-- if abs(p)<r1 then
			--  face(r+.6,a+p*0.01,lerp(j2,0.02,0.08),0.04,abs(p)<r2 and 7*17 or 17)
			-- end
			--end
			--eye dark
			face(r+.6,a,lerp(j,0.02,0.08),0.37-abs(j-0.5)*0.4,17)
			--eye light
			face(r+.85,a,lerp(j,0.047,0.073),0.22-abs(j-0.5)*0.3,7*17)
			--blush
			face(r+.4,a+i*lerp(j,0.03,0.07),0.01,0.3-abs(j-0.5)*0.3,14+8*16)
		end
		
		--arm
		local y=i*4.5
		for v=-1,1,0.25 do
			local s=sqrt(1-v*v)
			for a=0,0.9,0.1 do
				local x2=1+s*cos(a)*0.6
				local y2=y+v*1.2
				local z2=s*sin(a)
				y2,z2=rot(y2,z2,-i*0.08)
				x2,y2=rot(x2,y2,rb*0.5-i*0.06)
				gt_draw_new_voxel(
					x2,
					y2,
					z2+dz,
					0.3,
					14*17
				)
			end
		end
		
		--feet
		y=i*1.7
		for v=-1,1,0.25 do
			local s=sqrt(1-v*v)
			for a=0,0.8,0.2 do
				local x2=v*1.5
				local y2=y+s*cos(a)*1
				local z2=-5+s*sin(a)*0.4
				x2,z2=rot(x2,z2,ra*1.2)
				gt_draw_new_voxel(
					x2,
					y2,
					z2+dz,
					0.4,
					8*17
				)
			end
		end
	end
	
	--mouth
	local x,y,z=sphc(r+0.5,0,0)
	x,y=rot(x,y,ta)
	gt_draw_new_voxel(x,y,z+dz,0.08,0)
	
	frame+=1
end