Black/White Stripes

SDL Development
1

Hi!

I need for an experiment a stimulus with vertical repeated black/white
stripes (the whole screen) which moves from right to left.

What is the best way to realize this?

Hope anyone can help a newbie :slight_smile:

Thanks a lot.

Greetings Walter

2

I would use a rectangle drawing function
from a graphics library like SDL_gfx, SGE, or Sprig (or just use
SDL_FillRect if you’re comfortable with that). Then you can use an
integer variable to loop through one ‘wavelength’ of stripes (one
black, one white).

Here’s an (untested) example using Sprig (http://pubpages.unh.edu/~jmb97).

int stripeWidth = 40; // change this to whatever

int wavePos = 0;

bool done = 0;

while(!done)

{

// check for events

// ...





for(int i = 0; wavePos + i * stripeWidth < screen->w; i++)

{

    Uint32 color = (i%2 == 0) ? 0x000000 : 0xFFFFFF;

    SPG_RectFilled(screen, wavePos + i * stripeWidth, 0, wavePos + (i+1) * stripeWidth, screen->h, color);

}

wavePos--;

if(wavePos <= -2*stripeWidth)

    wavePos = 0;





// throttle framerate

// ...

}

If you need help filling in the rest, just send me an email.

Jonny D> Date: Wed, 4 Jun 2008 09:10:45 +0200

From: sdl at jokawalli.de
To: sdl at lists.libsdl.org
Subject: [SDL] Black/White Stripes

Hi!

I need for an experiment a stimulus with vertical repeated black/white
stripes (the whole screen) which moves from right to left.

What is the best way to realize this?

Hope anyone can help a newbie :slight_smile:

Thanks a lot.

Greetings Walter

SDL mailing list
SDL at lists.libsdl.org
http://lists.libsdl.org/listinfo.cgi/sdl-libsdl.org

Enjoy 5 GB of free, password-protected online storage.
http://www.windowslive.com/skydrive/overview.html?ocid=TXT_TAGLM_WL_Refresh_skydrive_062008