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Generate random patterns

Started by flyjason Mar 16, 2007 at 1:42 PM 9 replies 1.9k views

Original Post

Mar 16, 2007 at 1:42 PM

Hi, I would like to know how to create patterns randomly in OpenGL. What I mean is that let say I use a square and a triangle, and then mix them up so that it creates a kind of pattern. The pattern generated should be unique. That is, next time a pattern is generated, it should be different from the previous one. Perhaps OpenGL has some specific functions for performing these??... I need to know also how to save each newly generated pattern as a picture file (JPEG, GIF, etc). Thanks for helping.

NerdInHisShoe

Mar 16, 2007 at 5:56 PM

I still don't understand what you are trying to do. You mean randomly lay out polygons on a plane and get a random sort of design? Create a random sequence of shapes in a row?

flyjason

Mar 17, 2007 at 3:51 AM

I want to get a random sort of design yeah.

Laying out some polygons (possibly squares) and then create the design. The design should then be saved in JPEG/GIF format (3x3 inches).

When the program is executed again...a new design is created but should be unique in the sense that the previously created design should be different from the newly created ones. In other words, this imply that all design should be unique.

Any idea?

hoLogramm

Mar 17, 2007 at 4:25 AM

Maybe some sort of these babies?

Try to search for something like:

procedural

shape grammars

geometric substitution

L-grammars, graftals

Hope you find something useful.

h.

flyjason

Mar 18, 2007 at 9:47 AM

Have a look @ http://www.cs.utah.edu/gdc/projects/augmentedreality/

You'll see many patterns (they are basically variations of squares).

This is what I want to do...creating those patterns using OpenGL and save them in JPEG/GIF format.

JohnBolton

Mar 18, 2007 at 1:55 PM

Quote:
Original post by flyjason
I would like to know how to create patterns randomly in OpenGL. What I mean is that let say I use a square and a triangle, and then mix them up so that it creates a kind of pattern. The pattern generated should be unique. That is, next time a pattern is generated, it should be different from the previous one.
...
I need to know also how to save each newly generated pattern as a picture file (JPEG, GIF, etc).

This is more of a question about generating unique random patterns than a question about OpenGL.

You need to write an algorithm that uses a random number generator (such as rand) to generate a random image, then write code to create the image in memory or use OpenGL to draw the image in memory, then use an image library (such as DevIL) to write the image to a file.

As another alternative, you could use OpenGL to draw the image on the screen and then use screen capture to save it to a file.

flyjason

Mar 18, 2007 at 2:25 PM

Yeah I was thinking about using rand()...I know it generates random numbers.

How can it be of help to produce random images?

Any pseudocode?

Spoonbender

Mar 18, 2007 at 2:52 PM

Just call rand() for each pixel in the image, would be a simple answer.
Pseudocode:

foreach (column c in image){  foreach (pixel p in c){    p.red = rand()%256;    p.green = rand()%256;    p.blue = rand()%256;  }}

If you need anything more constructive or detailed, you have to provide some more information. What are you trying to achieve (at a higher level, that is. What do you need the generated shapes for, what are they meant to represent)

Knowing that is pretty important in order to be able to suggest ways to generate them.

Rand

Mar 18, 2007 at 3:09 PM

Or because those patterns were just black and white squares.

for(each pixel){   bool bWhite=rand()%2;   r=g=b=bWhite*255;}

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