Pixel Bender to Native Plugin

[françois leroy]

Hi!

I'm quite used to expressions, scripting, and pixel bender, but I don't know about programming (yet...).

I have a bunch of pixel bender plugins that I'd like to be native Plugins. And I don't really know how to start...

I figured out how to set my parameters and controls, compile into .aex.

But I still don't understand how to get my pixels coordinates, transform them (with a matrix or simple operations) and then render them...

for example, in pixel bender, I would have:

float2x2 myMatrix = some matrix value...

float2 pos = outCoord();

pos = pos*myMatrix;

dst = sampleLinear(src,pos);

can I do it, for example, in the skeleton file?

I saw the "put your interesting code here"... but don't know how to write that code!

If anyone can tell me, just on that example, it would be great!!

Thanx

PS: or is there somewhere an example of something similar to the Geometry effect?

[shachar carmi · Accepted solution]

i'm not too familiar with pixel bender, but from what i can gather you want to push values into arbitrary pixels.

it can be done with the c++ api, but more easily you could pull values.

take a look at the "shifter" sample.

it iterates through the output samples, and pulls input values from other locations.

if you can to see how to push values to random pixels , checkout the "CCU" sample project.

it shows how to access a buffer pixel directly in RAM.

you can't however, push subpixel values to 4 adjacent pixels.

not that it's impossible, i just don't know of any suite that does that.

[françois leroy]

Hi!

Thanx for your reply! I'll have a look at it. Also I just saw the next post, and I understand more the Effect/AEGP difference.

[françois leroy]

Hi!

I tried to dig into the SDK for a while now, and i think the GLator is the best base for me, as it is GPU accelerated.

But i have a few questions:

How do you switch the context from/to openGL and to/from AE?

Do you have a concrete example on how to do a black and white ramp from left to right?

For sure, rgb*colorDepth = x_coordinates/width, but how do you acces coordinates?

I saw examples on how to do it by rows/columns, but i think accessing coordinates directly is more efficient for what i need.

Any help will be highly appreciated! 🙂

Cheers,

Francois

[shachar carmi]

i think this thread has some info on that:

http://forums.adobe.com/message/4674493

look for the messages by gutsblow.

[françois leroy]

Hi Shachar,

thanx for your answer.

I already tried to follow the instructions in this discussion, but i'm missing something in the beginning:

I cannot find where we define the context.

Let me precise:

it seems DaveProx's way is :

[[myOpenglView openGLContext] makeCurrentContext];

    glClearColor(0, 0, 0, 1);

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glBlendFunc(GL_SRC_ALPHA,GL_ONE);

    glShadeModel(GL_SMOOTH);

    glEnable(GL_BLEND);

    draw_scene();

    glFlush();

But i can't find the place to put it in the whole code, cos' i couldn't guess where AE defines it's own context.

Can you help?

Or do you have a working framework for PC?

Thanx for your help!

Francois

[shachar carmi]

sorry man, i never did any openGL coding.

post your question on said thread, hopefully the people with the answers

are still subscribed to it.

[françois leroy]

OK, thanx anyway!

[Guest]

Hi jkhgsruigh.

What Shachar wrote works fine.

I just create a hidden window and  do all the opengl settings, then set my opengl context (I set it in objective c, but I think it should work both on windows and mac with proper code) like this:

(myOpenglView is an NSOpenglView object)

[[myOpenglView openGLContext] makeCurrentContext];

Then I do all my opengl drawings and flush the scene:

glFlush();

After that I use glReadPixels to grab the pixels and mix them with the input in AE  - that works perfectly.

Remember, don't use global variables, beacuse your plugin won't use multithreading render properly - I had to rewrite mine...

The tricky part comes with the Premiere Pro. Because it crashes everytime when I use opengl code. I had to write my stand alone application which is my renderer, but it's slow

It works, but I want my plugin to work as fast as in After Effects.

That's why I try to find a way to switch/change/freeze AE/Premier context for the time of the opengl drawings - maybe that's the way to do opengl in Premiere Pro. I don't know.

I even started this thread couple weeks ago:

http://forums.adobe.com/thread/1102663?tstart=0

But noone could answer me. Maybe I'll find the answer in this thread

Hope this helps

[françois leroy]

Hi Dave,

thanx a lot for these infos. I have to go deeper into the openGL itself.

I think i took bad habits from Pixel Bender, where coding is soooooo simple...

About Premiere, i can only wish you good luck

Cheers,

Francois ("jkhgsruigh" isn't my real name

[Guest]

That's not your real name? Damn...

Hope, I'll find all the answers here.

Good luck Francois aka jkhgsruigh

[Mike_Basil]

Is it not easier and faster to use Render to Texture + Render buffers? no offence but glReadPixels is a little 90s!

[Guest]

I like 90s

No worries, it'll be changed, I'm in the thesting moment right now.

Btw thanks for the tip

[françois leroy]

Hi again!

I've been trying to understand how the GLator works, but something's still going wrong...

I could switch the context (thanx Dave!) but i still got a problem with the texture coordinates:

glBegin(GL_QUADS); //input frame

glTexCoord2f(0.0f,0.0f);     glVertex3f(-0.5f * aspectF,-0.5f + yOffsetF,0.0f);

glTexCoord2f(0.7f,0.0f);     glVertex3f(0.5f * aspectF,-0.5f + yOffsetF,0.0f);

glTexCoord2f(0.7f,0.46f);     glVertex3f(0.5f * aspectF,0.5f + yOffsetF,0.0f);

glTexCoord2f(0.0f,0.46f);     glVertex3f(-0.5f * aspectF,0.5f + yOffsetF,0.0f);

glEnd();

where do the TexCoord2f values come from? why 0.7 and 0.46? I tried to change thoses values to 1.0, 0.5, disabled the perpective, but i can't make the texture match the quad...

Any help?

Sorry for such a beginner's question...

Thanx,

François