Hi, this is the converted Yabasic tetrader part of the demo.yab.
-- tetraeder.yab converted to Lua
opoints = {{-1,-1,1},
{1,-1,-1},
{1,1,1},
{-1,1,-1}}
triangles = {{1,2,4},
{2,3,4},
{1,3,4},
{1,2,3}}
points={}
for i=1,4 do
points[i]={}
end
page = 0
phi=0;dphi=0.1;psi=0;dpsi=0.05
r=60;g=20;b=0
dr=0.5;dg=1.2;db=3;dm=0
paper (65535)
repeat
activepage (page)
cls()
phi=phi+dphi
psi=psi+dpsi
for n=1, 4 do
points[n][1]=opoints[n][1]*math.cos(phi)-opoints[n][2]*math.sin(phi)
points[n][2]=opoints[n][2]*math.cos(phi)+opoints[n][1]*math.sin(phi)
p2= points[n][2]*math.cos(psi)-opoints[n][3]*math.sin(psi)
points[n][3]=opoints[n][3]*math.cos(psi)+ points[n][2]*math.sin(psi)
points[n][2]=p2
end
r=r+dr
if (r<0 or r>60) then
dr=-dr
end
g=g+dg
if (g<0 or g>60) then
dg=-dg
end
b=b+db
if (b<0 or b>60) then
db=-db
end
dm=dm+0.01
m=120-80*math.sin(dm)
for n=1, 4 do
p1=triangles[n][1]
p2=triangles[n][2]
p3=triangles[n][3]
n1=points[p1][1]+points[p2][1]+points[p3][1]
n2=points[p1][2]+points[p2][2]+points[p3][2]
n3=points[p1][3]+points[p2][3]+points[p3][3]
if (n3>0) then
sp=n1*0.5-n2*0.7-n3*0.6
ink ( hrgb( 60+r+30*sp,60+g+30*sp,60+b+30*sp))
filltriangle (screenwidth()/2+m*points[p1][1],screenheight()/2+m*points[p1][2],screenwidth()/2+m*points[p2][1],screenheight()/2+m*points[p2][2],screenwidth()/2+m*points[p3][1],screenheight()/2+m*points[p3][2])
end
end
visualpage (page)
page = page + 1
if page > 1 then
page = 0
end
sleep (12)
until keypressed()
