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Topic: BImage alpha: white or black? (Read 346 times) |
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Sjeiti
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BImage alpha: white or black?
« on: Jul 21st, 2004, 3:13pm » |
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hi... got something strange...
This draws a pixel and fades it by drawing an image over it with lots of alpha... only... although the image is white, the screen fades to black.
Code:BImage eImg;
void setup() {
size(200,200);
eImg = new BImage(width,height);
for (int i=0; i<eImg.pixels.length; i++) {
eImg.pixels[i] = color(255,255,255,10);
}
background(0);
strokeWeight(2);
stroke(255);
}
void loop() {
point( noise(millis()*.00011,millis()*.00012)*width, noise(millis()*.00013,millis()*.00014)*height);
image(eImg,0,0);
}
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even weirder... logically this code should have the same effect.. but it doesn't...
Code:BImage eImg;
void setup() {
size(200,200);
eImg = new BImage(1,1);
eImg.pixels[0] = color(255,255,255,10);
background(0);
strokeWeight(2);
stroke(255);
}
void loop() {
point( noise(millis()*.00011,millis()*.00012)*width, noise(millis()*.00013,millis()*.00014)*height);
image(eImg,0,0,width,height);
}
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..is this a bug?...
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http://www.sjeiti.com/
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toxi_
Guest
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Re: BImage alpha: white or black?
« Reply #1 on: Jul 21st, 2004, 4:21pm » |
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hey sjeti, you're right, there seems to be some discrepancy in the image() code for images with alpha channel.
btw. you can also use the blend() function to achieve a fade by replacing the line "image(eImg,0,0)" with this one:
Code:| blend(eImg,0,0,width,height,0,0,width,height,BLEND); |
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in case you're wondering why it never actually fades to 100% white, the answer is in this thread, which is about a related effect.
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Sjeiti
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Re: BImage alpha: white or black?
« Reply #2 on: Jul 21st, 2004, 8:13pm » |
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ah... ok.. thanks...
the thread clears things up a bit
(not that it was a real problem... just stumbled upon it when doing something completely different and needed a fast fade)...
...Sjeiti
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http://www.sjeiti.com/
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