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Index › Programming Questions & Help › Programs › Fast way to render offscreen buffer
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Fast way to render offscreen buffer? (Read 1414 times)
Frederik De Bleser
Fast way to render offscreen buffer?
May 31st, 2010, 10:01am  
I'm rendering path trails in an offscreen buffer and rendering the buffer:

Code:
// somewhere in setup()
trailBuffer = p.createGraphics(myWidth, myHeight, JAVA2D)

// somewhere in draw()
image(trailBuffer.get(), 0, 0)


After profiling, the get() method is a performance bottleneck since it clones the offscreen buffer, copying all the pixels to a new PImage.

Is there a faster way to blit the entire buffer?
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PhiLho 
Re: Fast way to render offscreen buffer?
Reply #1 - May 31st, 2010, 10:21am  
Code:
// somewhere in setup()
trailBuffer = p.createGraphics(myWidth, myHeight, JAVA2D);

// somewhere in draw()
image(trailBuffer, 0, 0);
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Frederik De Bleser
Re: Fast way to render offscreen buffer?
Reply #2 - May 31st, 2010, 12:01pm  
Thanks for the tip! It does work, but I had some weird results. If I try your suggestion,  I get the following error:

Code:
Exception in thread "Animation Thread" java.lang.NullPointerException
	at java.lang.System.arraycopy(Native Method)
	at sun.awt.image.IntegerInterleavedRaster.setDataElements(IntegerInterleavedRaster.java:427)
	at processing.core.PGraphicsJava2D.updatePixels(Unknown Source)
	at processing.core.PGraphicsJava2D.imageImpl(Unknown Source)
	at processing.core.PGraphics.image(Unknown Source)
	at processing.core.PApplet.image(Unknown Source)


However, if I store the results of trailBuffer.get() in an image first, everything works fine.  So now I do:

Code:
In setup():
PGraphics trailBuffer = p.createGraphics(myWidth, myHeight, JAVA2D);
PImage trailImage = trailBuffer.get();

In draw():
trailBuffer.endDraw();
trailImage = trailBuffer;
image(trailImage, 0, 0);


Thanks again for the tip! It does work faster now.
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PhiLho 
Re: Fast way to render offscreen buffer?
Reply #3 - Jun 1st, 2010, 1:00am  
You don't need trailImage. And the get() you do isn't useful, since you just overwrite the content you get.

The error you show is generally because of lack of beginDraw() or endDraw() around the drawing in the PGraphics.
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