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Topic: setting an alpha pixel (remove image pixel) (Read 349 times) |
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Andre_Michelle
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setting an alpha pixel (remove image pixel)
« on: Jul 31st, 2004, 6:56pm » |
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I believe, that is simple, but i don't get it.
Code:
BImage a;
BImage b;
void setup()
{
size( 100 , 100 );
a = loadImage( "blue.gif" );
b = loadImage( "green.gif" );
image( a , 0 , 0 );
image( b , 0 , 0 , 50 , 50 );
}
void loop()
{
b.set( mouseX , mouseY , color( 0 , 0 , 0 , 0 ) );
image( a , 0 , 0 );
image( b , 0 , 0 );
}
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Draw black Pixels, but want to set Pixels with Alpha = 0, so the upper image will be transparent.
Any suggestions ?
[edit]
Oh, even a transparent pixel.gif draws white(!) pixel.
[/edit]
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| « Last Edit: Jul 31st, 2004, 7:03pm by Andre_Michelle » |
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Andre_Michelle
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Re: setting an alpha pixel (remove image pixel)
« Reply #1 on: Aug 1st, 2004, 3:47pm » |
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Thats curious. An alpha channel with 0 seems not transparent, when adding him x times onto itself.
http://www.andre-michelle.com/processing/temp/
floating errors ?
Are there practices to avoid them in such case ?
Code:
Vector particles;
BImage pin;
void setup ()
{
size( 400 , 400 );
particles = new Vector();
imageMode( 2 );
pin = new BImage( 11 , 11 );
pin.set( 6 , 6 , color( 255 , 128 , 0 ) );
//pin = loadImage( "pin.gif" ); // transparant with 1 px set.
}
void loop ()
{
background(133);
particles.addElement( new Particle( pin.copy() , pmouseX , pmouseY , 0.1 , 50 ) );
Particle p;
for ( Enumeration e = particles.elements() ; e.hasMoreElements(); )
{
p = (Particle)(e.nextElement());
p.render();
}
}
void destroy( Particle p )
{
particles.removeElement( p );
}
class Particle
{
BImage img;
int lifeTime;
float falloff;
int x, y;
int timer;
Particle( BImage img, int x, int y, float falloff, int lifeTime )
{
this.img = img;
this.x = x;
this.y = y;
this.falloff = falloff;
this.lifeTime = lifeTime;
timer = 0;
}
public void render()
{
if ( ++timer > lifeTime ) destroy( this );
image( img , x , y );
}
}
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This is a simple ParticleMouse. If you stay a second, the alpha channel goes gray.
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| « Last Edit: Aug 1st, 2004, 3:49pm by Andre_Michelle » |
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JohnG
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Re: setting an alpha pixel (remove image pixel)
« Reply #2 on: Aug 3rd, 2004, 5:49pm » |
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The loadImage function doesn't load alpha channels, you have to put them into a seperate image, load them, then use them, e.g.:
void setup()
{
size(200,200);
BImage Image=loadImage("Image1.jpg"); //the image
BImage Alpha=loadImage("Image1.gif"); //the alpha mask
Image.alpha(Alpha);
background(color(128,128,12 );
image(Image,32,32);
}
( http://www.hardcorepawn.com/Alpha/ )
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