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Index › Programming Questions & Help › OpenGL and 3D Libraries › a newbie question abt flight404's opengl particles
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a newbie question abt flight404's opengl particles (Read 1792 times)
Allan Yong
a newbie question abt flight404's opengl particles
Mar 18th, 2010, 3:49pm  
Hey all,

I was trying to build something based on that SRC particle system,

fromflight404.com/blog/?p=115

I have fixed the texture binding problem,

but the floor and everything's y axis are reflected.

So like the force drives the particles go upwards.

I guess it would be a quick fix, any reply would be much appreciated!

Allan
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Quark
Re: a newbie question abt flight404's opengl particles
Reply #1 - Mar 18th, 2010, 4:08pm  
The standard coordinate system for OpenGL has the Y axis pointing up. In Processing the OPENGL render-er has the y axis pointing down to match the other render-ers.

That might be the cause.
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Allan Yong
Re: a newbie question abt flight404's opengl particles
Reply #2 - Mar 18th, 2010, 4:49pm  
Thank you Quark,

Is there an easy way I could switch one of them around?

Thank you again.

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Allan Yong
Re: a newbie question abt flight404's opengl particles
Reply #3 - Mar 18th, 2010, 5:34pm  
seems if I remove the perspective function, the first tutorial works fine.

Guess there is something to do with near plane, and far plane then.
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num3ric
Re: a newbie question abt flight404's opengl particles
Reply #4 - Mar 26th, 2010, 11:02pm  
I've been staying away from processing lately because of problems related to this. My older projects do not work anymore. So tonight I decided I would really try to isolate the error. By the way, this wasn't happening in version 1.0.5.

Ok so, here are the modifications I made:

In the _gl tab, I added a negative sign to the y coordinates, for gl.glTranslate. Ex:
gl.glTranslatef( _loc.x, -_loc.y, _loc.z );

If I remember correctly, I also reversed the sign of the y coord in the camera constructor (pov tab):
cam       = new Camera( parent, 0, 100, 1500 );

Here is the source, now functionning in the latest version:
http://www.cs.mcgill.ca/~erenau1/p5/particle_emitter.zip

Tell me if it's working for you also.

Now the question is, why only in the lastest versions What has changed Where is the problem emerging from Or maybe it was uncorrect before, and now things are in the right vertical order

Éric
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