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  Checking is a pixel transparent or not??  (Read 741 times)
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Offline role

Junior Member




Java manmoth is coming!


« Posted 2005-01-26 15:41:36 »

Hello I need to know a pixel is transparent or not.
I convert a color of an image to transparent with this function :
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BufferedImage image;
int x, y;

int col = image.getRGB(x, y);
image.setRGB(x, y, col & 0x00ffffff);

The color of the image in coordinate x, y is converted to transparent.

Now i need to check whether the color is transparent or not :
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BufferedImage image;
int x, y;

int col = image.getRGB(x, y);

if (col == ????) {
   System.out.println("transparent color");
} else {
   System.out.println("opaque color");
}

Anyone know about this?

What I'm confuse is the transparent color of a new created blank image (GraphicsConfiguration.createCompatibleImage(width, height, Transparency.BITMASK)) is 0, but when I use above code to convert a color to transparent, the transparent color is not 0?Huh


Thanks

Golden T Game Engine - Java2D/OpenGL Game Engine
Golden T Website | Golden T Forum
Offline jbanes

JGO Coder


Projects: 1


"Java Games? Incredible! Mr. Incredible, that is!"


« Reply #1 - Posted 2005-01-26 15:53:41 »

To solve your testing problem, you can use a bitwise operation:
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if((col & 0xFF000000) == 0x00) 
{
    System.out.println("transparent color");
}
else
{
    System.out.println("opaque color");
}


Checking for partial transparency can be done with:

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if((col & 0xFF000000) != 0xFF000000)


Any questions?

Edit: Took me a few tries to get the code right. ;-)

Java Game Console Project
Last Journal Entry: 12/17/04
Offline role

Junior Member




Java manmoth is coming!


« Reply #2 - Posted 2005-01-26 22:41:22 »

Wow thanks a million jbanes!!!
Now my pixel perfect collision working perfectly!! Wohoo!! Grin
Thanks thanks thanks Wink

Golden T Game Engine - Java2D/OpenGL Game Engine
Golden T Website | Golden T Forum
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