Help with basic animation

[mattman]

hey i need some help with a project. I need to know how to make a night sky twinkle. like stars and clouds . Any Ideas????

[Sean]

You could run a low colour at first, then after a certain time, it clears quickly, and the new ones come in and switch back and forth, to add the twinkle effect.

[mattman]

heres what i got soo far
colourback (black)

loop
cls
drawfillstar (500, 500, 200, 200, yellow) % stars
delay (100)

drawfillstar (200, 200, 300, 300, yellow)
delay (100)
cls

drawfillstar (150, 150, 200, 200, yellow)
delay (100)
cls

drawfillstar (100, 100, 120, 120, yellow)
delay (100)
cls

drawfillstar (75, 75, 50, 50, yellow)
delay (100)
cls

end loop


any ideas???

[mattman]

its only a shooting star but anything to make it look better?

[HeavenAgain]

add a back ground colour of black maybe, draw a ground, with grass, trees, and a house, and you standing there, and theres a lot of starts on the sky, and then suddenly add your shooting star in it, that would be nice

[Zampano]

For your shooting star, you should instead use a loop in which the previous star is erased, then the x1 and y1 go down by a certain amount, and x2, and y2 go down by a lesser amount (so that the star is bigger than it used to be); something like this:

code:

setscreen ("offscreenonly") var x1, x2, y1, y2 : int x1 := 400 y1 := 300 x2 := 500 y2 := 400 loop     drawfillstar (x1, y1, x2, y2, 0)     x1 -= 2     x2 -= 1     y1 -= 2     y2 -= 1     drawfillstar (x1, y1, x2, y2, 14)     View.Update end loop

If that violates compsci.ca's policy concerning posting code, then please remove it. I only posted it because I thought it was pretty basic.

[mattman]

wow thankz for that budz but when u did the
x1 -= 2
x2 -= 1
y1 -= 2
y2 -= 1
drawfillstar (x1, y1, x2, y2, 14)
View.Update
what are the varibles doing?? and why did you draw another star?? just wondering cuz this is neat

[HeavenAgain]

y1 -= 1 is short for y1 = y1 - 1
and drawing another star in white is to earse the previous draw star, so its like cls, but smaller -> only for the star you draw instead of the whole screen. I think!

[mattman]

okay i see soo saying x1 -=2 is saying that your getting rid of x2 and x1? and vice versa??? sorry im farly new to this.. and veiw.update does what to the star?

[Zampano]

No, what -= or += does is add the amount after the syntax to the integer or real variable specified.
So in the case of y1 -= 2, every time the code executes, the 2 is taken away from the variable called y1.
You might have been thinking that the variable is destroyed because it has 'x' in its name, but that's just programming convention. I'm only taking away 2 from the value of the variable, the name means nothing.

HeavenAgain is right. The first star is drawn in colour 0, which is white. The second star is drawn in fourteen, which is the yellow that you see.
If you want to learn more about the line that follows (View.Update), then you should look here:
http://compsci.ca/v3/viewtopic.php?t=12533
Just scroll down to the area where View.Update is taught.

[mattman]

THANKS!!! i get it now! i appreciate the help!

[Sean]

Post your finished program soon, can't wait to see what you have done.

[mattman]

k

[mattman]

heres what i got do you think he'll like it for a gr 10? if not any suggestions to make it better cuz i cant get some of the stars to more in the right position
setscreen ("offscreenonly")
colourback(black)%setting background colour
cls
var x1, x2, y1, y2, a1, a2, b1, b2, c1, c2, d1, d2, e1, e2, f1, f2: int % set variables
x1 := 700% declare variables
y1 := 600
x2 := 750
y2 := 400
a1 :=500
b1 :=400
a2 :=600
b2 :=500
c1 := 450
d1 := 700
c2 := 400
d2 := 700
e1 := 650
f1 := 600
e2 := 300
f2 := 500

loop
drawfillstar(e1,f1,e2,f2,black)%stars in motion
e1-=2
e2-=1
f1-=2
f2-=1
drawfillstar(e1,f1,e2,f2,14)
drawfillstar(c1,d1,c2,d2,black)
c1-= 2
c2-=1
d1-=2
d2-=1
drawfillstar (c1,d1,c2,d2,14)
drawfillstar (a1,b1,a2,b2,black)
a1 -= 2
a2 -= 1
b1 -= 2
b2 -= 1
drawfillstar (a1,b1,a2,b2,14)

drawfillstar (x1, y1, x2, y2, black)
x1 -= 2
x2 -= 1
y1 -= 2
y2 -= 1
drawfillstar (x1, y1, x2, y2, 14)
View.Update
end loop



big thanks for the x1-= thing from Zampano:) it helped alot