Why aren't two of my rectangles showing up? - processing

void setup(){
size(100,100);
fill(255,255,255);
rect(0,0,50,50);
rect(50,50,100,0);
rect(50,50,0,100);
rect(50,50,100,100);
}
void draw(){
}
void mousePressed(){
if ((mouseX <= 50) && (mouseY <= 50)){
fill(random(0,255),random(0,255),random(0,255));
rect(0,0,50,50);
}
if ((mouseX >= 50) && (mouseY >= 50)){
fill(random(0,255),random(0,255),random(0,255));
rect(50,50,100,100);
}
if ((mouseX >= 50) && (mouseY <= 50)){
fill(random(0,255), random(0,255), random(0,255));
rect(50,50,100,0);
}
if ((mouseX <= 50) && (mouseY >= 50)){
fill (random(0,255),random(0,255),random(0,255));
rect(50,50,0,100);
}
}
Hello, I am a new programmer recently introduced to Processing 3. When I run this code, 2 squares are missing (top right and bottom left). I've reviewed the code but I do not see any errors. If someone knows what is wrong in the code, please let me know.
Any help is greatly appreciated.
Thanks!

Let's take a look at the reference for the rect() function:
By default, the first two parameters set the location of the upper-left corner, the third sets the width, and the fourth sets the height.
Now let's look at the two lines of code you're having trouble with:
rect(50,50,100,0);
This rectangle will be 0 pixels tall, so you won't see it. Similarly:
rect(50,50,0,100);
This rectangle will be 0 pixels wide, so you won't see it.
I'm guessing that you're thinking that the last two parameters are the lower-right corner, but that's not the case by default. Of course, you could change this using the rectMode() function:
rectMode(CORNERS);

Related

Constrain mouse daw to 45degrees Processing

How does one constrain interactively drawing a line to 45degrees?
Imagine there in an underlining grid that's at 45 degees which the mouse draw is magnetized too. Perhaps on mousedown decides which your starting position is and after that your Mouse.X and Mouse.Y position only update in 45 degrees from that starting click?
float dif = 10;
float easing = 0.05;
boolean current = false;
boolean started = false;
float rainbow, x, y;
float colbase;
PVector pos, prev_pos, update_pos;
float step = 25;
void setup(){
size(400, 400);
background(100);
colorMode(HSB);
}
void draw(){
if (rainbow >= 255) rainbow=0; else rainbow+=5;
if (frameCount % dif == 0) {
colbase = rainbow;
}
if(mousePressed){
update_pos();
if(current){
started = true;//start drawing
pos = update_pos;
}else{
prev_pos = update_pos;
}
current = !current;
}else{
update_pos();
started = false;
pos = update_pos;
prev_pos = update_pos;
}
if(started){
//style for lines
strokeWeight(step);
stroke(colbase,255,255);
noFill();
line(prev_pos.x, prev_pos.y, pos.x, pos.y);
}
}
PVector update_pos(){
x = lerp(x, mouseX, easing);
y = lerp(y, mouseY, easing);
update_pos = new PVector(x, y);
return update_pos;
}
I would like to say that I like this. Also, that this question was ultimately way harder to answer than I though it would be.
Here's the result:
First, I took the liberty to reorganize your example code. I don't know how experienced you are, and maybe some of the things I changed were on purpose, but it seemed to me that your example had a lot of weird code bits dangling. Here's the example code with my changes (check the next code block for the answer, this one is more like a code review to help you in general):
float dif = 10;
float easing = 0.05;
boolean current, started; // automatically initializing as false unless stated otherwise
float rainbow;
float colbase;
PVector pos, prev_pos;
float step = 25;
void setup() {
size(400, 400);
background(100);
colorMode(HSB); // clever!
pos = prev_pos = new PVector(); // instanciating some non-null PVectors
}
void draw() {
pos = prev_pos = update_pos(); // cascade attribution: it starts by the last one and goes back toward 'pos'
if (mousePressed) {
if (!started) {
// initializing variables needed for drawing
started = true;
pos = prev_pos = new PVector(mouseX, mouseY);
}
} else {
started = false;
}
if (started) {
updateColor();
strokeWeight(step);
stroke(colbase, 255, 255);
noFill();
line(prev_pos.x, prev_pos.y, pos.x, pos.y);
}
}
void updateColor() {
if (rainbow >= 255) {
rainbow=0;
} else {
rainbow+=5;
}
if (frameCount % dif == 0) {
colbase = rainbow;
}
}
PVector update_pos() {
float x = lerp(pos.x, mouseX, easing);
float y = lerp(pos.y, mouseY, easing);
return new PVector(x, y);
}
Notice how I changed a couple variables names. As a general rule, you should always name your variables as if the guy maintaining your code was an angry biker who knows where you live.
Now to solve your actual question:
boolean isDrawing;
float rainbow, colbase, dif, easing, step, centerZone;
PVector pos, prev_pos, origin, quadrant;
void setup() {
size(400, 400);
background(100);
colorMode(HSB); // clever!
centerZone = 5; // determine how close to the original click you must be to change quadrant
dif = 10;
easing = 0.05;
step = 25;
origin = pos = prev_pos = new PVector();
}
void draw() {
updatePosition();
if (mousePressed) {
if (!isDrawing) {
// setting variables needed for drawing
isDrawing = true;
origin = pos = prev_pos = new PVector(mouseX, mouseY); // drawing should always start where the mouse currently is
}
} else {
isDrawing = false;
}
if (isDrawing) {
updateColor();
strokeWeight(step);
stroke(colbase, 255, 255);
noFill();
line(prev_pos.x, prev_pos.y, pos.x, pos.y);
}
}
void updateColor() {
if (rainbow >= 255) {
rainbow=0;
} else {
rainbow+=5;
}
if (frameCount % dif == 0) {
colbase = rainbow;
}
}
void updatePosition() {
float relativeX = pos.x - origin.x;
float relativeY = pos.y - origin.y;
float diffX = mouseX - origin.x;
float diffY = mouseY - origin.y;
float distance = abs(diffX) > abs(diffY) ? abs(diffX) : abs(diffY); // this is just inline if, the syntax being " condition ? return if true : return if false; "
prev_pos = pos;
// validating if the mouse is in the same quadrant as the pencil
PVector mouseQuadrant = new PVector(diffX > 0 ? 1 : -1, diffY > 0 ? 1 : -1);
// we can only change quadrant when near the center
float distanceFromTheCenter = abs(relativeX) + abs(relativeY);
if (quadrant == null || distanceFromTheCenter < centerZone) {
quadrant = new PVector(diffX > 0 ? 1 : -1, diffY > 0 ? 1 : -1);
}
// if the mouse left it's quadrant, then draw toward the center until close enough to change direction
// ^ is the XOR operator, which returns true only when one of the sides is different than the other (one true, one false)
// if the quadrant info is positive and the diff coordinate is negative (or the other way around) we know the mouse has changed quadrant
if (distanceFromTheCenter > centerZone && (relativeX > 0 ^ mouseQuadrant.x > 0 || relativeY > 0 ^ mouseQuadrant.y > 0)) {
// going toward origin
pos = new PVector(lerp(prev_pos.x, origin.x, easing), lerp(prev_pos.y, origin.y, easing));
} else {
// drawing normally
pos = new PVector(lerp(prev_pos.x, origin.x + (distance * quadrant.x), easing), lerp(prev_pos.y, origin.y + (distance * quadrant.y), easing));
}
}
I'll answer your questions on this code if you have any. Have fun!
EDIT:
This part could use more explainations, so let's elaborate a little bit:
if (distanceFromTheCenter > centerZone && (relativeX > 0 ^ mouseQuadrant.x > 0 || relativeY > 0 ^ mouseQuadrant.y > 0)) {
// going toward origin
} else {
// drawing normally
}
The point of this check is to know if the mouse is still in the same quadrant than the "pencil", by which I mean the point where we're drawing.
But what are the "quadrants"? Remember, the user can only draw in 45 degrees lines. Theses lines are defines in relation to the point where the user clicked to draw, which I call "origin":
Which means that the screen is always divided into 4 different "quadrants". Why? Because there is 4 different directions where we can draw. But we don't want the user to have to stick to these exact pixels to be able to draw, do we? We could, but that's not how the algo is working: it poses a pencil on the page and then follows the mouse. So here if the mouse goes up-left from origin, the pencil will draw on the up-left branch of the 45 degrees X lines. Each of these imaginary lines has it's own "part of the screen" where they control where the pencil has the right to draw, which I call "quadrants":
Now with this algorithm we can force the pencil over the 45 degrees lines, but what happens if the mouse goes from one quadrant to another one? I figured out that the pencil should follow, but without breaking the "only drawing in 45 degrees lines" rule, so it has to go through the center before changing quadrant:
There is no big secret here. It's kind of easy to figure the business rules we want to apply:
While the mouse and the pencil are in the same quadrant, follow the mouse's position to draw (but only on the line).
If the mouse is in a different quadrant from the pencil, draw toward the center, then toward the mouse normally.
Which is exactly what we're doing here:
if (mouse and pencil are in different quadrants) {
// draw toward origin
} else {
// draw toward the mouse
}
Then... if it's so simple, why this convoluted code?
(distanceFromTheCenter > centerZone && (relativeX > 0 ^ mouseQuadrant.x > 0 || relativeY > 0 ^ mouseQuadrant.y > 0))
Well, really, it could be written in a waaay easier to read way, but it would be longer. Let's decompose it and see why it's written this way:
My operational logic here go as follow:
As you probably know, point (0,0) is on the upper-left side of the sketch. Most drawing in computer science calculate coordinates this way.
Quadrants exist in relation to the origin point (where the user clicked to start drawing).
Relative coordinates in each quadrant will be either positive or negative. X will be positive if they are to the right of origin. Y will be positive if they are lower in the screen than origin:
If you follow my logic, when relative coordinate of the mouse and pencil aren't both positive or both negative in the same way, it would mean that they are not located in the same quadrant.
So:
distanceFromTheCenter > centerZone => when we're close enough to the center, we can let the pencil switch direction. No need to calculate the rest if the pencil isn't near the center.
relativeX > 0 ^ mouseQuadrant.x > 0 => relativeX is really just pos.x - origin.x. It's where the pencil is in relation to origin. mouseQuadrant "knows" where the mouse is in relation to the origin (it's just diffX and diffY as interpreted for later use, in fact we totally could have used diffX and diffY instead as we just compare if they are positive or negative numbers)
Why the XOR operator if it's so simple? Because of this:
relativeX > 0 ^ mouseQuadrant.x > 0
// is the same thing than this pseudocode:
if (relativeX sign is different than mousequadrant.x's sign)
// and the same thing than this more elaborated code:
!(relativeX > 0 && mouseQuadrant.x > 0) || !(relativeX < 0 && mouseQuadrant.x < 0)
// or, in a better writing:
(relativeX > 0 && mouseQuadrant.x < 0) || (relativeX < 0 && mouseQuadrant.x > 0)
...which is also convoluted and also ugly. So, really, (relativeX > 0 ^ mouseQuadrant.x > 0 || relativeY > 0 ^ mouseQuadrant.y > 0) is just a short hand for:
(!(relativeX > 0 && mouseQuadrant.x > 0) || !(relativeX < 0 && mouseQuadrant.x < 0) || !(relativeY > 0 && mouseQuadrant.y > 0) || !(relativeY < 0 && mouseQuadrant.y < 0))
I hope this just made sense! Have fun!

Moving image leaving trail and directional movement according to mouse position -Processing

So I managed to make most of the exercise but can't think of a way to make the trail of the moving image. Also, in the video ball moves in the direction of mouse position.
However, when I tried to do that, mouse position is changing every time and the ball is following the mouse while moving. The velocity had to be calculated using the mouse position. Any help would be appreciated.
This is how it should look: https://streamable.com/9jdc3
My code:
PImage ball, bFire;
int xPosB, yPosB, bW, bH, bFW, bFH, velocityX, velocityY;
boolean bMoving;
void setup() {
size(1024, 512);
//loading images
ball = loadImage("ball.png");
bFire = loadImage("ballFire.png");
//resizing images
ball.resize(ball.width/4, ball.height/4);
bFire.resize(bFire.width/4, bFire.height/4);
//starting values
//ball
xPosB = width/2;
yPosB = height/2;
}
void draw() {
background(0);
//draw ball
imageMode(CENTER);
image(ball, xPosB, yPosB);
//draw fire ball
if (bMoving) {
image(bFire, xPosB, yPosB);
xPosB+=velocityX;
yPosB+=velocityY;
}
//colision detection
if (xPosB-bFire.width/2 <= 0 || xPosB+bFire.width/2 >= width) {
velocityX*=-1;
} else if (yPosB-bFire.height/2 <= 0 || yPosB+bFire.height/2 >= height) {
velocityY*=-1;
}
}
void mousePressed() {
if (mouseButton == LEFT) {
bMoving=!bMoving;
velocityX = mouseX/100;
velocityY = mouseY/100;
}
}
I can't repoduce the problem you describe - of the ball following the mouse.
I can tell you that the mousepressed() you use is incorrect.
You assign the velocity, but because mouseX and mouseY will always be positive the ball will always move to the right and down.
Try the code below, it sets the velocity to the difference between the mouse and the current position of the ball. The ball will now always move towards the mouse.
void mousePressed() {
if (mouseButton == LEFT) {
bMoving=!bMoving;
velocityX = (mouseX - xPosB) / 50;
velocityY = (mouseY - yPosB) / 50;
}
Second point: I don't know how your ballFire.png looks, but right now it is drawn at the exact same X/Y location of the ball. This cannot give you a trailing effect, for that you'll have to draw the fireball a little behind the ball.
Try the code below:
//draw fire ball
if (bMoving) {
image(bFire, xPosB-velocityX, yPosB-velocityY);
xPosB+=velocityX;
yPosB+=velocityY;
}
//draw ball
imageMode(CENTER);
image(ball, xPosB, yPosB);
It draws the fireBall behind the ball based on the velocity. So faster means more distance. You can tweak this distance of course. If you want multiple firballs as trailing effect, draw the fireball multiple times with different offsets.
Final note: you'll want to draw the ball last, else the fireball will be drawn half over the normal ball.

How do I change the color from white to black step by step of a rectangle, when I move my mouse away?

I have a question. How do I change the color of a rectangle from white to black step by step, when I move my mouse away? I'm kinda new to this.
I've tried a bit:
void setup () {
size (200,200);
}
void draw () {
background (0);
stroke (255);
line (100,0,100,200);
line (0,100,200,100);
// Fill a black color
noStroke ();
fill (255);
// Depending on the mouse location, a different rectangle is displayed.
if (mouseX < 100 && mouseY < 100) {
rect (0,0,100,100);
} else if (mouseX > 100 && mouseY < 100) {
rect (100,0,100,100);
} else if (mouseX < 100 && mouseY > 100) {
rect (0,100,100,100);
} else if (mouseX > 100 && mouseY > 100) {
rect (100,100,100,100);
}
}
I would appreciate that, if anyone could help me.
Thanks.
The call fill(255); is setting the rectangle color to white. Use fill(0); to set the rectangle to black, or fill(x); for any value x between 0 and 255 for shades of grey.
To make a fade, you'll need to draw multiple rectangles (drawing all of them is easiest) on each draw() call. The current box will be in white, where the mouse is. Others will be fading to black. So you'll need variables for each box indicating its current color.
Here's my version:
int boxColor1;
int boxColor2;
int boxColor3;
int boxColor4;
void setup () {
size (200,200);
boxColor1 = boxColor2 = boxColor3 = boxColor4 = 0;
}
void draw () {
background (0);
// Fill a black color
noStroke ();
// Subtrack 10 from each box color, but don't go below zero
boxColor1 = max( 0, boxColor1-10 );
boxColor2 = max( 0, boxColor2-10 );
boxColor3 = max( 0, boxColor3-10 );
boxColor4 = max( 0, boxColor4-10 );
// Depending on the mouse location, a different rectangle is displayed.
if (mouseX < 100 && mouseY < 100) {
boxColor1 = 255;
} else if (mouseX > 100 && mouseY < 100) {
boxColor2 = 255;
} else if (mouseX < 100 && mouseY > 100) {
boxColor3 = 255;
} else if (mouseX > 100 && mouseY > 100) {
boxColor4 = 255;
}
fill (boxColor1);
rect (0,0,100,100);
fill (boxColor2);
rect (100,0,100,100);
fill (boxColor3);
rect (0,100,100,100);
fill (boxColor4);
rect (100,100,100,100);
// Draw edge lines last, over the top
stroke (255);
line (100,0,100,200);
line (0,100,200,100);
}
If there are a lot of boxes, you should use an array, or some data structure instead of many different variables like boxColor1, boxColor2 etc.
If I understand your question, you want to show a grid of rectangles, and you want a rectangle to turn white and stay white when the mouse exits that rectangle. Is that right?
If so, then you need to keep track of whether each rectangle should be black or white. The simplest approach might be a 2D array of boolean values. Each cell in the array will represent a single square in your grid.
Set the corresponding cell in the array to true when you want that square to turn white. Then loop over the array and draw each square using the values in the array to determine the color.

Processing - show one circle at a time

I have written this code which, on a mouse button press, increases or decreases the number of circles visible, equally spaced around a circle.
int nbr_circles = 2;
void setup() {
size(600, 600);
smooth();
background(255);
}
void draw() {
background(255);
float cx = width/2.0;
float cy = height/2.0;
fill(0);
//float x, y; //
for (int i = 0; i < nbr_circles; i++)
{
float angle = i * TWO_PI / nbr_circles;
float x = cx + 110.0 * cos(angle);
float y = cy + 110.0 * sin(angle);
ellipse(x, y, 20, 20);
}
}
void mousePressed() {
if (mouseButton == LEFT) {
if (nbr_circles < 20)
nbr_circles = nbr_circles + 1;
} else if (mouseButton == RIGHT) {
if (nbr_circles > 2)
nbr_circles = nbr_circles - 1;
}
}
I would like to alter the code so that, with nbr_circles fixed at 10, only one circle is visible at a time, each in turn in successive frames.
I have changed the code a little. The mouse buttons do nothing and the nbr_circles is fixed at 10.
How can I now show one circle at a time?
show circle #1 -> hide circle #1, show circle #2 -> hide circle #2, show circle #3 … -> hide circle #9, show circle #10 -> hide circle #1, show circle #1…
Adjusted code - where is it going wrong?
int nbr_circles = 2;
int i = 1;
void setup () {
size (600, 600);
}
void draw () {
background (255);
fill (0);
float cx = width/2.0;
float cy = height/2.0;
float angle = i * TWO_PI / nbr_circles;
float x = cx + 110.0 * cos(angle);
float y = cy + 110.0 * sin(angle);
ellipse(x, y, 20, 20);
}
if (mouseButton == LEFT) {
if (ellipse(x,y,20,20))
rotate (angle);
}
Thanks in advance.
Taking a step back, I really suggest you start a bit smaller, instead of posting a new question every time you get stuck. It looks like you've got a fundamental misunderstanding of the basic syntax of Processing, so maybe you should go back and do some tutorials until you're more comfortable in it. That's probably the most "correct" answer I can give you, even though it's probably not what you're looking for.
To answer the question of why your adjusted code doesn't work, it's because none of the syntax makes sense. First of all, you've got an if statement outside of a function, which isn't valid. When do you expect that if statement to be executed?
Secondly, you've got the ellipse() function inside an if statement, but the ellipse() function doesn't return a boolean. What do you expect that to do? And finally, what do you expect that rotate function to do?
It seems like you're trying to copy-paste code you found on the internet without really understanding any of it. That's not going to work. You have to take a step back and understand the basics before you can expect to make a program that actually does what you want it to do.
If you edit your "adjusted code" to fix the problems I pointed out, I'll try to help you through the process, but you really should consider going back and starting smaller before trying to get somebody else's code you found on the internet to work.

Removing an image border using opencv

I have a lot of images with a thick white border around them. What's the easiest way for me to remove/isolate these borders? Anyway I can do this using OpenCV?
Not a very elegant solution, but here's my first attempt.
if( direction == BORDER_SEARCH_DIRECTION.TOP ||
direction == BORDER_SEARCH_DIRECTION.BOTTOM )
{
for (int y = startY; y >= 0 && y < _image.Height; y += deltaY)
{
bool foundNonWhite = false;
for (int x = startX; x < _image.Width; x += deltaX)
{
if (Convert.ToInt32(_image.ManagedArray.GetValue(y, x, 0)) < BORDER_WHITENESS_THRESHOLD)
{
foundNonWhite = true;
break;
}
}
if (!foundNonWhite)
{
borderAt = y;
break;
}
}
}
Basically, this assumes that a border will start at most a fifth of the way into the image from the top/bottom, and it searches for the first row that is completely "white". I run the routine twice and if I find an entire row of white on the top and bottom of the image, I assume we have a border.
Damn thing takes 250 milliseconds.
One approach would be to use quad-tree decomposition such that the border area is a "leaf" node. Then you can subtract it out.

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