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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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 Posted: Thu Oct 30, 2003 5:59 am Post subject: Easy Starfields |
[quote] |
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I've discovered what I find to be an easy way to create starfield simulations.
heres the code:
| Code: |
DEFINT A-Z
CONST QUITSTATE = 255
CONST RUNSTATE = 1
TYPE StarTyp
x AS INTEGER
y AS INTEGER
xv AS INTEGER
clr AS INTEGER
END TYPE
CONST MAXSTARS = 650
DIM SHARED Stars(MAXSTARS) AS StarTyp
DIM SHARED State
CLS
SCREEN 7, 0, 1, 0
FOR index = 0 To 255
OUT &H3c8, index
OUT &H3c9, i + 64
OUT &H3c9, i + 64
OUT &H3c9, i + 64
NEXT
FOR index = 0 To MAXSTARS-1
Stars(index).x = INT(RND*319)
Stars(index).y = INT(RND*199)
Stars(index).xv = -2 * INT(RND * 3) + -1
Stars(index).clr = INT(RND * 15) + 1
NEXT
DO
CLS
K$ = INKEY$
IF K$ = CHR$(27) THEN State = QUITSTATE
FOR index = 0 To MAXSTARS-1
' move stars
Stars(index).x = Stars(index).x + Stars(index).xv
IF Stars(index).x < 0 THEN Stars(index).x = 319
' draw stars
PSET(Stars(index).x,Stars(index).y), Stars(index).clr
NEXT
PCOPY 1,0
LOOP UNTIL State = QUITSTATE
SCREEN 0
WIDTH 80
SYSTEM
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enjoy.
questions, comments welcome.
_________________
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Rambling Indie Games, LLC
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Last edited by DeveloperX on Thu Nov 18, 2004 11:27 pm; edited 1 time in total
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Hajo
Demon Hunter
Joined: 30 Sep 2003
Posts: 779
Location: Between chair and keyboard.
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| Posted: Fri Nov 12, 2004 9:47 am Post subject: |
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Hi,
after your announcement to write a book and your hint that you already wrote some articles, I started to look at your articles.
I've got a few comments to this proposed starfield algorithm.
1) Stars only move in X-direction but not in Y-direcion. I think you forgot the Y component of the movement vector
2) Even if the Y move problem is fixed, it doesn't generate a good impression of depth. "Stars" closer to the screen borders ought to move faster than those close to the center of the screen. Your demo is missing this effect.
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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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| Posted: Mon Nov 15, 2004 7:10 pm Post subject: |
[quote] |
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| Hajo wrote: | Hi,
after your announcement to write a book and your hint that you already wrote some articles, I started to look at your articles.
I've got a few comments to this proposed starfield algorithm.
1) Stars only move in X-direction but not in Y-direcion. I think you forgot the Y component of the movement vector
2) Even if the Y move problem is fixed, it doesn't generate a good impression of depth. "Stars" closer to the screen borders ought to move faster than those close to the center of the screen. Your demo is missing this effect. |
I didn't miss anything in my demo.
You missed the point of it. :)
I created a starfield that moves to the left. It isn't meant to move along the Y axis, nor is it supposed to have any 'depth'
for it. It is a _simple_ 2D starfield for you to learn the technique .
Anyway, what you described would be a simulated 3d starfield demo, where you're 'flying' through it, like, say the windows screensaver. I never intended my demo to be like that, and I've recieved emails regarding this very post, thanking me for writing it, cause it cleared up the technique, and made it easy to understand.
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Rambling Indie Games, LLC
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Hajo
Demon Hunter
Joined: 30 Sep 2003
Posts: 779
Location: Between chair and keyboard.
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| Posted: Tue Nov 16, 2004 8:21 am Post subject: |
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I'm sorry for misreading the code.
A few comments might be helpful to get the reader on the right track ;)
Maybe we can use the misunderstanding to do something good: In your new book, be careful that all examples are easy understandable and well commented.
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Happy
JonA's American snack pack
Joined: 03 Aug 2002
Posts: 200
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| Posted: Tue Nov 16, 2004 1:32 pm Post subject: Re: Easy Starfields |
[quote] |
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| DeveloperX wrote: | | I've discovered what I find to be an easy way to create starfield simulations. |
I don't think that simulates starfields! Stars move slower the further they are from the viewer! Also, comments in the code would be more than welcome! Thanks for sharing your wonderful (but useless) discovery!
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Bjorn
Demon Hunter
Joined: 29 May 2002
Posts: 1425
Location: Germany
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| Posted: Tue Nov 16, 2004 5:37 pm Post subject: |
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I think anybody that knows how to add numbers and keep an array (like, knows how to program) automatically is able to simulate a starfield given the ability to paint dots to a screen, with simulated depth even.
As such this whole example came to me as useless the first time it was posted, unless it was meant as a creative example for people trying to get to grips with for loops, arrays and pixel drawing.
Of course I'm not talking about doing it in true 3D, which requires some additional mathematical background.
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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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| Posted: Tue Nov 16, 2004 8:07 pm Post subject: |
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Guys, I wrote this post last year!
Back when I was just learning about velocity and shit.
I only posted it cause I thought it would be helpful for a newbie programmer.
Also, in regards to the comment bout my book:
All examples are, infact overly commented, so that even a complete newbie could grasp the concepts.
There are 2 versions of the code, heavily commented (for newbies), and generally commented (for intermediate programmers).
Anyway, please, enough about how my year old post contains useless information, geez.
_________________
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Rambling Indie Games, LLC
See my professional portfolio
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Bjorn
Demon Hunter
Joined: 29 May 2002
Posts: 1425
Location: Germany
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| Posted: Tue Nov 16, 2004 9:50 pm Post subject: |
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Really, I agree.
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Happy
JonA's American snack pack
Joined: 03 Aug 2002
Posts: 200
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| Posted: Tue Nov 16, 2004 9:53 pm Post subject: |
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It's rather hard to forget about it when you make it sticky.
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BadMrBox
Bringer of Apocalypse
Joined: 26 Jun 2002
Posts: 1022
Location: Dark Forest's of Sweden
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| Posted: Thu Dec 09, 2004 3:28 pm Post subject: |
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Well, unstick it.
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Bjorn
Demon Hunter
Joined: 29 May 2002
Posts: 1425
Location: Germany
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| Posted: Thu Dec 09, 2004 6:30 pm Post subject: |
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I'm pretty sure it was unsticked ages ago now. :-)
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DeveloperX
202192397
Joined: 04 May 2003
Posts: 1626
Location: Decatur, IL, USA
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