line 2 quad - help with math - Processing Forum

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jeff_g

line 2 quad - help with math

in Programming Questions • 2 years ago

I have a line (defined by two points), which I want to replace with a quad. Any idea on how to convert the 2 points of a line into the corresponding four points for a quad?

Replies(4)

cedrickie..

Re: line 2 quad - help with math

2 years ago

i had the same question about a year ago.
and figured out a way to do it

anyway here is my code, hope it helps.

void setup(){
size(400,400);
}
void draw(){
background(255);
float lineWidth = 20;
float x2 = 150;
float y2 = 80;
float x = mouseX;
float y = mouseY;
float tx = bezierTangent(mouseX, mouseX, 150, 150,0.5);
float ty = bezierTangent(mouseY, mouseY, 80,80,0.5);
float a = atan2(ty, tx);
a -= HALF_PI;
stroke(255,0,0);
line(150,80,mouseX,mouseY);
stroke(0);
fill(0,40);
beginShape(QUAD_STRIP);
vertex(cos(a)*lineWidth + x, sin(a)*lineWidth + y);
vertex(cos(a)*-lineWidth + x, sin(a)*-lineWidth + y);
vertex(cos(a)*lineWidth + x2, sin(a)*lineWidth + y2);
vertex(cos(a)*-lineWidth + x2, sin(a)*-lineWidth + y2);
endShape();
}

jeff_g

Re: line 2 quad - help with math

2 years ago

Awesome! How would you modify that for 3d?

cedrickie..

Re: line 2 quad - help with math

2 years ago

hmm not sure, you can just add a z coordinate, but i guess you want it to face to the camera all the time, do you want to replace a line with a quad to scale in 3d mode ?

maybe take a look at quarks shape library, you can use it to create a tube out of lines, even beziers.
http://www.openprocessing.org/visuals/?visualID=11096

jeff_g

Re: line 2 quad - help with math

2 years ago

Appreciate the help, but I think I've found another solution.

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