Rotating cube in TIC-80

tic80.lua

BPM =80

function v3(x,y,z)
	return {x,y,z}
end


model = {
	vertices = {
		v3(-1,-1,-1),
	 v3( 1,-1,-1),
		v3(-1, 1,-1),
		v3( 1, 1,-1),
		v3(-1,-1, 1),
		v3( 1,-1, 1),
		v3(-1, 1, 1),
		v3( 1, 1, 1),
	},
	normals = {
		v3(-1, 0, 0),
		v3( 1, 0, 0),
		v3( 0,-1, 0),
		v3( 0, 1, 0),
		v3( 0, 0,-1),
		v3( 0, 0, 1),
	},
	lines = {
		1,2,
		2,4,
		4,3,
		3,1,

		5,6,
		6,8,
		8,7,
		7,5,

		1,5,

		2,6,

		3,7,

		4,8,
	},
	triangles = {
		10,1,2,4,6,
		10,3,1,4,6,

		11,5,6,8,5,
		11,7,5,8,5,

	}
}

function to_screen(ww,p)
	local w = ww*10/(10+p[3])	
	local x = (p[1]*w+1)*68+52
	local y = (p[2]*w+1)*68
	return {x,y}	
end

function transform(t, vs)
	local a = t
	local b = math.sqrt(0.5)*a
	local c = math.cos(a)
	local s = math.sin(a)
	local cc= math.cos(b)
	local ss= math.sin(b)
	local nvs = {}
	for i = 1,#vs do
		local v = vs[i]
		local x0 = v[1]
		local y0 = v[2]
		local z0 = v[3]

		local x1 = c*x0+s*y0
 	local y1 = -s*x0+c*y0
		local z1 = z0

		local x2 = cc*x1+ss*z1
		local y2 = y1
 	local z2 = -ss*x1+cc*z1

		nvs[i] = {x2,y2,z2}
	end
	return nvs
end

function TIC()
	local t = time()/1000.0

	cls(15);

	local sa = t
	sa = math.pi*2*sa*0.25*BPM/60
	local sx = 4
	local sy = 40+40*math.sin(sa)
	spr(0,sx,sy,0,1,0,0,16,6)
	spr(96,sx+128,sy,0,1,0,0,13,6)

	local b = math.pi*2*t*BPM/60.0
	local ww = 0.2*math.pow(0.5+0.5*math.sin(b), 10.0)+0.5

	local points = {}
	local vertices = transform(t, model.vertices)
	for i=1,#vertices do
		points[i] = to_screen(ww, vertices[i])
	end

	local normals = transform(t, model.normals)

	local triangles = model.triangles
	for i=1,#triangles,5 do
		local a = triangles[i]
		local b = points[triangles[i+1]]
		local c = points[triangles[i+2]]
		local d = points[triangles[i+3]]
		local e = normals[triangles[i+4]]
		if e[3] > 0 then
			tri(b[1],b[2],c[1],c[2],d[1],d[2],a)
		end
	end
	

	local lines = model.lines
	for i=1,#lines,2 do
		local f = points[lines[i]]
		local t = points[lines[i+1]]
		local v = vertices[lines[i]]
		local w = vertices[lines[i+1]]
		local c = ((v[2]+w[2])+2)*2
		line(f[1],f[2],t[1],t[2],11)
	end

	local a = t
	a = a*0.5*BPM/60.0
	local y = a-math.floor(a)
	y = y-0.5
	y = y*y
	y = 20+300*y
	x = 80+80*math.sin(a)
	print("Beat dis TCB!!!",x, y,(8*t)%16)

end