How do I write a trig equation in processing?

in Programming Questions • 2 years ago

Okay I'm editing my post to make more sense...

basically, I am trying to get the blue line in the sketch match the angle of the black line that completes the right angle triangle between two randomly generated points.

Heres my code:

float randx1;
float randy1;

float randx2;
float randy2;

float plus=0;

void setup() {
size(500, 500);

// randx1 = random(0, width/2);
randx2= random(width/2, width);

// randy1 = random(height);
randy2= random(height);
}

void draw() {
background(255);
float mouseMove= constrain(mouseX, 0, width/2);
randx1= mouseMove;
randy1= mouseY;

//split tank line
line(width/2, 0, width/2, height);

// red= 1
noStroke();
fill(255, 0, 0);
ellipse(randx1, randy1, 10, 10);

// green 2
noStroke();
fill(0, 255, 0);
ellipse(randx2, randy2, 10, 10);

stroke(255, 0, 0);
//imaginary triangle
//line(randx1, randy1, randx1, randx1++);
strokeWeight(3);

//---------------------if RED is 'higher up' than green-----------------------------------
// if red ellipse
if (randy1 < randy2) {
    stroke(255, 0, 0);

    //horizontal for red (1)
    line(randx1, randy1, randx2, randy1);

    //vertical for green (2)
    line(randx2, randy2, randx2, randy1);

    ///------------ROTATED LINE... im trying to get this blue line to 'follow' the black one

    stroke(0, 0, 255);
    strokeWeight(3);

    //--------calculations

    // hypotenuse
    float h= dist(randx1, randy1, randx2, randy2);
    println("h is: " + h);

    //opposite (rise)
    float o= dist(randx2, randy2, randx2, randy1);
    println("o i: " + o);

    float thing= sin(o/h);
    float p = degrees(thing);
    println("thing is: " + thing);

    //------------- blue line

    pushMatrix();
    translate(randx1, randy1);
    rotate(thing);
    line(0, 0, 50, 0);
    popMatrix();
}

//---------------------if GREEN is 'higher up' than red---------------------------------------
// green
if (randy2 < randy1) {
    stroke(0, 255, 0);
    //horizontal for green (2)
    line(randx2, randy2, randx1, randy2);

    stroke(255, 0, 0);
    //vertical for red (1)
    line(randx1, randy1, randx1, randy2);

    ///------------ROTATED LINE... im trying to get this blue line to 'follow' the black one

    stroke(0, 0, 255);
    strokeWeight(3);

    //--------calculations

    // hypotenuse
    float h= dist(randx1, randy1, randx2, randy2);
    println("h is: " + h);

    //opposite (rise)
    float o2= dist(randx2, randy2, randx2, randy1);
    o2=o2*(-1);
    println("o2 i: " + o2);

    float thing= sin(o2/h);
    float p = degrees(thing);
    println("thing is: " + thing);

    //------------- blue line

    pushMatrix();
    translate(randx1, randy1);
    rotate(thing);
    line(0, 0, 50, 0);
    popMatrix();
}

//------------diagonal

stroke(0);
strokeWeight(1);
line(randx1, randy1, randx2, randy2);

}

Replies(6)

PhiLho

Re: How do I write a trig equation in processing?

2 years ago

I am a bit in a hurry, so I haven't analyzed fully the question or code, but a way to get an angle from two points is to use the atan2 function. Search the forums to see how to use it.

bjordal

Re: How do I write a trig equation in processing?

2 years ago

Your code is kinda messy (and hard to read) but here's basically what you're looking for. Also try to avoid using translate and rotate.

float randx1,randy1,randx2,randy2;

void setup() {
size(500, 500);
randx2= random(width);
randy2= random(height);
}

void draw() {
background(255);
randx1= mouseX;
randy1= mouseY;

/////////////layout code\\\\\\\
//draw points
noStroke();
fill(0,255,0);
ellipse(randx2, randy2, 10, 10);
ellipse(randx1, randy1, 10, 10);
//draw lines between points
strokeWeight(1);
stroke(0);
line(randx1,randy1,randx2,randy2);
strokeWeight(3);
stroke(255,0,0);
line(randx1,randy2,randx2,randy2);
line(randx1,randy2,randx1,randy1);

///////////// interesting code \\\\\\\\\\\\\\\
//draw blue line
stroke(0,0,255);
float angle = atan2(randy2-randy1,randx2-randx1);
line(randx1,randy1,randx1+cos(angle)*50,randy1+sin(angle)*50);
}

riot_theo..

Re: How do I write a trig equation in processing?

2 years ago

Wow thankyou so much! Thats exactly what I was trying to do. After phi_lho had suggested using atan2 I've vbeen trying to use it all morning with no luck, but this code is great.

Only problem is, the reason I was using rotate is because this is a preliminary sketch for something else... Im going to be 'placing' a wave form from a sound track between two constantly moving points, which is why I wanted the rotation and the angle because (as far as I know) thats the only way to manipulate a wave form... you cant set x and y positions for that.

I'll try and glimpse what I can out of your code, its still a step in the right direction.

fizzyp

Re: How do I write a trig equation in processing?

2 years ago

Why should I avoid using translate? I suspect it's slower because, underlying it all, it's keeping track of some Affine transformation (see pushMatrix() and popMatrix()). Is this why you make this suggestion?

bjordal

Re: How do I write a trig equation in processing?

2 years ago

Nope it's not slower, it's just bad practice and can easily give you lots of trouble. I can't think of any good example but i know there has been some threads where people have had trouble with collision detection (and things like that) because of translate/rotate/scale because they started using relative and absolute coordinates 'n stuff. So just try to avoid using it.

PhiLho

Re: How do I write a trig equation in processing?

2 years ago

There is precisely such thread recently: http://forum.processing.org/topic/array-confuses-translate
But here, unlike there, fizzyp is using pushMatrix, so is out of trouble (or in a different set of trouble...).
translate() and other transformations are powerful, but can easily confuse people (even experienced ones).

Top Reply

Response title

Attachments

New to this Portal?