small problem image visibility multiply

Programming Questions

alexx600

small problem image visibility multiply

in Programming Questions • 8 months ago

Hello. I have got small problem.

I have got 2 imgages in draw function.images are crossing/overlaping? I do not know how to explain it. I use threeshold filter and i have got problem which visibility. I would like to have got black material pixel visibility but white- transparent (i would like to use multiply). But my images are rotated, I am a litte bit confused.

My explanation can be very unclearly-there is photo.

Now it should be more clear. Thanks for any help:)

Replies(5)

amnon.owed

Re: small problem image visibility multiply

8 months ago

Depending on which Processing version you are using you can use blend() or blendMode() to achieve this.

See the reference.

alexx600

Re: small problem image visibility multiply

8 months ago

I am using 1.5.1.Yes I know I can use that. But i have got

sx int: X coordinate of the source's upper left corner

sy int: Y coordinate of the source's upper left corner

It is a litte bit confusing to me. Probably i should sin and cos function to have that coordinate?

sx	int: X coordinate of the source's upper left corner
sy	int: Y coordinate of the source's upper left corner

alexx600

Re: small problem image visibility multiply

8 months ago

Maybe my code will be usefull
PImage img;
PVector pos;
void setup(){
background(255);
size(800,600);
smooth();
pos = new PVector(400, 300);
}
void draw(){
background(255);
img = loadImage("elep"+".jpg");
frameRate(25);
int r=frameCount;
//noLoop();
point(width/2, height/2);
pushMatrix();
translate(width/2,height/2);
rotate(radians(frameCount));
image(img, -img.width/2,40);
popMatrix();
pushMatrix();
translate(width/2,height/2);
rotate(radians(frameCount+90));
//blend(img, ceil(sin(radians(r))*20)-img.width/2, int(sin(radians(r*4))*20), ceil(sin(radians(r))*20)-img.width/2, 100, int(sin(radians(r*4))*20), 0, img.width, img.height, MULTIPLY);
blend(img, 0, 0, width, height, 400, 200, img.width, img.height, MULTIPLY);
popMatrix();
//blend(img,30+ceil(sin(radians(r))*20),30+ceil(sin(radians(r*4))*20),500,500,0,0,500,500,MULTIPLY);
//blend(img, 0, 0, img.width, 100, img.height, 0, img.width, img.height, MULTIPLY);
print(frameCount);
filter(THRESHOLD);
}

amnon.owed

Re: small problem image visibility multiply

8 months ago

It seems blend() is rectangular only. So rotation is not possible. The easiest workaround is to draw the rotated image to a PGraphics and blend the whole PGraphics. The end-result is the same, except there is one step in between.

On a sidenote: never load images in draw(). You are loading your image 60 times per second. Instead load it only once in setup().

Code Example

PImage img;
PGraphics pg;
void setup() {
size(800, 600);
pg = createGraphics(width, height, JAVA2D);
img = loadImage("http://www.colourbox.com/preview/1957595-149357-elephant-black-silhouette-isolated-on-white-background-abstract-art-illustration.jpg");
imageMode(CENTER);
smooth();
}
void draw() {
background(255);
translate(width/2, height/2);
image(img, 0, 0);
pg.beginDraw();
pg.background(0, 0);
pg.imageMode(CENTER);
pg.translate(width/2, height/2);
pg.rotate(radians(frameCount));
pg.image(img, 0, 0);
pg.endDraw();
blend(pg, 0, 0, pg.width, pg.height, 0, 0, width, height, MULTIPLY);
}

alexx600

Re: small problem image visibility multiply

8 months ago

Thanks for help. It is really helpfull. Furthermore I can use PNG file and alpha is visible. Now my problem is solved.

Thanks for advice. I would load img in setup fuction:)

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