Processing 1.0 - Processing Discourse - Video with alpha channel

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Index › Programming Questions & Help › OpenGL and 3D Libraries › Video with alpha channel

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Video with alpha channel (Read 2194 times)

peripecio

Video with alpha channel
Jun 9^th, 2010, 4:25am

Hi!

I'm trying to draw a video (.mov) with alpha channel as a opengl texture. I'm using jmcvideo library.

I create my JMCMovieGL with ARGB pixelformat:

myMovie = new JMCMovieGL(this,"movie_w_alpha.mov",PImage.ARGB);

and draw in OpenGL mode. In this code i draw two movies to check if alpha channel is working or not:

PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;

GL gl = pgl.beginGL();
{
myMovie.image(gl, 0, 0, myMovie.width, myMovie.height);
myMovie.image(gl, width/2, 0, myMovie.width, myMovie.height);
}
pgl.endGL();

But this doesn't work.

Any idea?

Thanks in advance!

Guillermo

peripecio

Re: Video with alpha channel
Reply #1 - Jun 9^th, 2010, 12:17pm

OK, i've got it.

One have to set the blending conditions. Just two lines:

gl.glEnable (gl.GL_BLEND);
gl.glBlendFunc (gl.GL_ONE, gl.GL_SRC_ALPHA);

(gl.glBlendFunc (gl.GL_ONE, gl.GL_ONE); works too)

This allow us to work with transparency in the next videos or images to draw.

So, final code is:

myMovie = new JMCMovieGL(this,"movie_w_alpha.mov",PImage.ARGB);

and draw in OpenGL mode. In this code i draw two movies to check if alpha channel is working or not:

PGraphicsOpenGL pgl = (PGraphicsOpenGL) g;

GL gl = pgl.beginGL();
{

gl.glEnable (gl.GL_BLEND);
gl.glBlendFunc (gl.GL_ONE, gl.GL_SRC_ALPHA);

myMovie.image(gl, 0, 0, myMovie.width, myMovie.height);
myMovie.image(gl, width/2, 0, myMovie.width, myMovie.height);
// you can draw other videos with (or not) transparency)
// mySecondMovie.image(gl, width/2, 0, myMovie.width, myMovie.height);
}
pgl.endGL();

I hope this will serve you!

Ciao!

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