I have a very strange problem. Everything in my code works super fine, but I still have an issue.
import processing.serial.*;
float r_height;
float r_width;
float hypotnuse;
int d = 20;
float x ;
float y ;
float ledGlow;
Serial myPort; // Create object from Serial class
void setup () {
size (510, 510);
String portName = Serial.list()[8];
myPort = new Serial(this, portName, 9600);
background (0);
fill(204);
ellipseMode (CORNER);
x = 0;
y = 0;
ellipse (x, y, d, d);
}
void draw () {
r_height = mouseY - y;
r_width = mouseX - x;
println ("Height is " + r_height);
println ("Width is " + r_width);
hypotnuse = sqrt (( (sq(r_height)) + (sq (r_width)) ) );
ledGlow = round (hypotnuse/2.84);
myPort.write(ledGlow);
println (ledGlow);
}
I need to get values 0-255 from the hypotenuse of my triangle. but when I am writing it to the serial port (myPort.write (ledGlow)), i need those values to be flipped. So if the hypotenuse is 0, it actually needs to equal to 255, if it's 1 it needs to be 254 and so on. I am not sure how to approach this problem.
Can you just subtract the hypotenuse from 255 at that time, to get the flipped hypotenuse value?
new_hypotenuse = 255 - hypotenuse ;
Related
I’m trying to make 6 dots along a line(0, random(height), width, random(height)). The dots should be evenly spaced.
You can use lerp(start, end, t) to linearly interpolate between to values by specifying t: where in between the start/end values you'd like the result to be.
This t value is between 0.0 and 1.0 (normalised value). You can think if of it as percentage. (e.g. 0.0 is at the start (0%) value, 1.0 is at the end value(100%), 0.5 is 50% between the start and end value).
In your case, you would:
store the randomly generated values first (before interpolation)
iterate 6 times, and for each iteration
for each iteration, map the iteration index to the normalised value (t)
Finally, use lerp() by plugging in the from/to values and the t value at the current iteration.
Here's a basic example:
float fromX = 0;
float fromY = random(height);
float toX = width;
float toY = random(height);
int numPoints = 6;
for(int i = 0 ; i < numPoints; i++){
float interpolationAmount = map(i, 0, numPoints - 1, 0.0, 1.0);
float interpolatedX = lerp(fromX, toX, interpolationAmount);
float interpolatedY = lerp(fromY, toY, interpolationAmount);
ellipse(interpolatedX, interpolatedY, 9, 9);
}
Alternatively you can use PVector's lerp() to easiely interpolate between points in 2D (or 3D), without having to interpolate every component:
PVector start = new PVector(0 , random(height));
PVector end = new PVector(width, random(height));
for(float t = 0.0 ; t <= 1.0 ; t += 1.0 / 5){
PVector inbetween = PVector.lerp(start, end, t);
ellipse(inbetween.x, inbetween.y, 9, 9);
}
Update
The slope is the ratio (division) between the difference on Y axis (called rise, Δy = y2 - y1 (E.g. toY - fromY)) and the difference on the X axis (called run, Δx = x2 - x1 (e.g. toX - fromY)).
You can use this difference between start and end points (defining the slope) to draw the points in between.
If you divide this difference into equal sections, each for a point you'd like to draw, then you can multiply it as you iterate and simply translate/offset it from the start position:
// start point
float fromX = 0;
float fromY = random(height);
// end point
float toX = width;
float toY = random(height);
// difference between each component
float diffY = toY - fromY;
float diffX = toX - fromX;
// slope = ratio between Y and X difference
float slope = diffY / diffX;
println("slope as ratio", slope, "as degrees", degrees(atan2(diffY, diffX) + PI));
// start drawing 6 points
int numPoints = 6;
// precalculate a sixth
float sectionIncrement = 1.0 / (numPoints - 1);
for(int i = 0 ; i < 6; i++){
// a sixth incremented (e.g. 1/6 * 0, * 1, *2, ...)
float section = sectionIncrement * i;
// a sixth incremented and mulitplied to the difference
// e.g. 1/6 of slope difference, 2/6 of slope / etc.
// to which we offset the start location (fromX, fromY +)
float x = fromX + (diffX * section);
float y = fromY + (diffY * section);
// render
ellipse(x, y, 9, 9);
}
point(0, random(height))
point(width/5, random(height))
point(width/5*2, random(height))
point(width/5*3, random(height))
point(width/5*4, random(height))
point(width, random(height))
I am currently going through Daniel Shiffman's 'The Nature Of Code', and have been playing around with one of the first exercises - a simple 'RandomWalker()'. I have implemented similar things in Java & had no trouble, however for some reason my walker always seems to go in more or less the same direction:
RandomWalker
This happens 100% of the time. Here is my code:
class Walker
{
int x;
int y;
// Constructor
Walker()
{
x = width / 2;
y = height / 2;
}
void display()
{
stroke(0); // Colour
point(x, y); // Colours one pixel in
}
void step()
{
float stepX;
float stepY;
stepX = random(-1, 1);
stepY = random(-1, 1);
x += stepX;
y += stepY;
}
}
Walker w;
void setup()
{
size(640, 360);
w = new Walker();
background(255);
}
void draw()
{
w.step();
w.display();
}
Is this some artefact of the random function? My first thought is that it's something to do with the pseudorandom nature of the function but the textbook specifically states that this should not be noticeable, and yet this happens every single time. I was wondering if maybe there's something wrong with my code?
Thanks in advance.
Your x and y variables are both int types. That means that they don't have a decimal part, so any time you add or subtract from them, they are truncated. Here are some examples:
int x = 1;
x = x + .5;
//1.5 is truncated, and x stays 1
int x = 1;
x = x - .5;
//.5 is truncated, and x becomes 0
This is why you see your x and y variables only decreasing. To fix this, just change x and y to float types, so they keep track of the decimals.
If you really need x and y to be int values, then you need stepX and stepY to also be int values:
int stepX;
int stepY;
stepX = (int)random(-5, 5);
stepY = (int)random(-5, 5);
x += stepX;
y += stepY;
But you probably just want to store x and y as float values.
PS: I love random walkers!
I am trying to draw a Gaussian curve with mean = 0 and standard deviation = 1 using processing, but when my code runs, nothing is drawn to the screen (not even the background).
Here is my code:
float x, y, mu, sigma;
void setup() {
size(900, 650);
background(255);
stroke(0);
strokeWeight(1);
mu = 0.0;
sigma = 1.0;
for(int i = -4; i < 4; i += 0.5) {
x = i;
y = (1/(sigma * sqrt(2 * PI)))*(exp((-1 * sq(x - mu)) / (2 * sq(sigma)) ));
x = map(x, -4, 4, 0, width);
y = map(y, 0, 1, 0, height);
point(x, y);
}
}
void draw() {
}
In your for loop, you are using an int as the counter, but you're incrementing it by 0.5. When i is positive and it is incremented, that 0.5 gets truncated and i remains what is was before-- so the loop runs forever. It's a fun observation that i does increase when it is negative-- truncation works towards zero, so adding 0.5 ends up adding 1. Changing the declaration of i from int i = -4 to float i = -4 fixed it on my computer. You may also want to increase the stroke weight, at least temporarily, to verify that the points are being drawn (they were hard to see for me and I wasn't sure it was working at first).
I am trying to make some objects, say 12, to rotate in an ellipse path continuously in Processing. I got a sketch which does rotation in a circle and I want to make it to rotate in a ellipse. I have some pointer from processing forum but the code from the pointer is different from the code that I posted and I couldn't understand yet (weak in trigonometry).
I googled a bit and found a post trying to achieve this with this algorithm:
You need to define your ellipse with a few parameters:
x, y: center of the ellipse
a, b: semimajor and semiminor axes
If you want to move on the elipses this means that you change the
angle between the major axes and your position on the ellipse. Lets
call this angle alpha.
Your position (X,Y) is:
X = x + (a * Math.cos(alpha));
Y = y + (b * Math.sin(alpha));
In order to move left or right you need to increase/decrease alpha and
then recalculate your position. Source:
http://answers.unity3d.com/questions/27620/move-object-allong-an-ellipsoid-path.html
How do I integrate it into my sketch? Thank you.
Here's my sketch:
void setup()
{
size(1024, 768);
textFont(createFont("Arial", 30));
}
void draw()
{
background(0);
stroke(255);
int cx = 500;
int cy = 350;
int r = 300; //radius of the circle
float t = millis()/4000.0f; //increase to slow down the movement
ellipse(cx, cy, 5, 5);
for (int i = 1 ; i <= 12; i++) {
t = t + 100;
int x = (int)(cx + r * cos(t));
int y = (int)(cy + r * sin(t));
line(cx, cy, x, y);
textSize(30);
text(i, x, y);
if (i == 10) {
textSize(15);
text("x: " + x + " y: " + y, x - 50, y - 20);
}
}
}
Replace
int r = 300; //radius of the circle
with
int a = 350; // major axis of ellipse
int b = 250; // minor axis of ellipse
and replace
int x = (int)(cx + r * cos(t));
int y = (int)(cy + r * sin(t));
with
int x = (int)(cx + a * cos(t));
int y = (int)(cy + b * sin(t));
first post here, and probably an easy one.
I've got the code from Processing's reference site:
float a = 0.0;
float inc = TWO_PI/25.0;
for(int i=0; i<100; i=i+4) {
line(i, 50, i, 50+sin(a)*40.0);
a = a + inc;
}
http://processing.org/reference/sin_.html
However, what I need is a line that follows the curve of a Sin wave, not lines representing points along the curve and ending at the 0 axis. So basically I need to draw an "S" shape with a sin wave equation.
Can someone run me through how to do this?
Thank you in advance,
-Askee
To draw a curve you need to store the previous point's position.
float a = 0.0;
float inc = TWO_PI/25.0;
float prev_x = 0, prev_y = 50, x, y;
for(int i=0; i<100; i=i+4) {
x = i;
y = 50 + sin(a) * 40.0;
line(prev_x, prev_y, x, y);
prev_x = x;
prev_y = y;
a = a + inc;
}