10 replies to this topic

[vanhoa]

try this code:

require "draw"

function drawlevel(h)
local p=pict.screen()
p=pict.part(p,1,0,159,100)
draw.clear()
draw.pict(0,0,p)
draw.line(159,0,159,h)
end

t=0
showgraph()

while not(getkey()) do
t=t+.1
drawlevel(10+10*math.sin(t))
end

nothing happen when you press a key (not EXE), but if you tap and then drag the stylus ...

because of draw.update() i think.

[vanhoa]

If you use this code:

require "draw"
showgraph()

function iif(con,a,b)
if con then return a else return b end
end

function drawlevel(h)
local p=pict.screen()
p=pict.part(p,4,0,159,200)
draw.clear()
draw.pict(0,0,p)
draw.line(156,0,156,h,1,4)
draw.line(156,200,156,h+50,1,4)
end

t=0
k=94

while not(testkey(K_EXE)) do
for i=1,50000 do end
t=t+iif(t>k,-t,.2)
drawlevel(75+50*math.sin(t/10)+10*math.sin(t))
end

It doesnt happen.

[Orwell]

Sorry, but what is supposed to happen here?
I can't see anything strange when I try to run it

Btw, you should write

while getkey()==nil do

instead of

while not(getkey()) do

because getkey() returns nil (and not false) if no key is pressed.
not(testkey(K_EXE)) is ok however.

[vanhoa]

Try the first code, you will see what happen: when you drag the stylus the update function not works, DRAG IT. The screen wont draw correctly!

[Orwell]

Everything runs fine on my ClassPad
Anyone else could try?

But I still don't see why the stylus would cause a problem, and why you talk about draw.update(), which is not used here...

[vanhoa]

Sorry, the first code must be:

require "draw"
draw.onbuffer()

function drawlevel(h)
local p=pict.screen()
p=pict.part(p,1,0,159,100)
draw.clear()
draw.pict(0,0,p)
draw.line(159,0,159,h)
draw.update()
end

t=0
showgraph()

while not(getkey()) do
t=t+.1
drawlevel(10+10*math.sin(t))
end

[Orwell]

Now I see what you mean... And indeed there is a problem
Thanks, I'll investigate

[vanhoa]

The next ver should add a function iif.

[Orwell]

Using iif() is a good idea, however it would not be a good idea to create a C++ function for it, because calling this function would be slower than executing it
I think it's not a big deal to write it again in your programs

[vanhoa]

Slow! Really! Maybe because that function must calc all a and b, but how about check con before parse a or b.

[Orwell]

No, it would be slow because of the operations needed to call a C++ function, which are heavier than a call to a simple Lua function