Hi,

The sketch below produces two vector fields. Part of the third last method called calculateField() is commented out. Uncommenting that section calculates an average for theta and magnitude for the two fields and should then plot a single vector field which would be the sum of the two fields.

Firstly the fields are not summing correctly and secondly moving the charges, only one seems to effect the overall field. (The fields can be changed by holding down the left mouse button and dragging the charges around.)

1. int numCharges = 2;//the number of charges
2. Electrons[] charge = new Electrons[numCharges];//Declare the 1D array called 'charge', the elements of which are objects of the class called 'Electrons'
3. int numVectorsX = 21;//20*30 that's number of vectors across by spacing between each is width and add 1 to the number of vectors in the x-direction
4. int numVectorsY = 11;//10*30 that's number of vectors down by spacing between each is height and add 1 to the number of vectors in the y-direction
5. int distance = 30;//spacing between vectors, same for x and y directions
6. Field[][] vectors = new Field[numVectorsX][numVectorsY];//Declare the 2D array called 'vectors', the elements of which are objects of the class called 'Field'
7. float targetX = 300, targetY = 150, pol, fieldStrength, minDiameter, maxDiameter;//the field initially points to a singularity at the coordinate (300,150). targetX and targetY is where the field points to. 'pol' is the polarity of the charge
8. float theta = 0;//angle between charge and each vector
9. float magnitude = 0;//length or magnitude of a vector
10. float fieldTransparency = 0;
11. int r, g, b;//red green blue variables for charge colour
12. float Fieldstrength;
13. int countCharges = -1;
14. void setup() {
15.   size(600, 300);
16.   smooth();
17.   noStroke();
18.   for (int k = 0; k < numCharges; k++) {//these loops populate the 2D array, each element of this array is an object and each object is a vector
19.     //x, y, r, g, b, transparency, count, initial diameter, minChargediameter, maxChargediameter... the fields
20.     charge[k] = new Electrons(100 + (100*k), 100 + (50*k), 0, 0, 255, 30, 1, 100, 20, 400); //Construct the object charge
21.   }
22.   float maxdist = 400;
23.   for (int i = 0; i < numVectorsX; i++) {//these loops populate the 2D array, each element of this array is an object and each object is a vector
24.     for (int j = 0; j < numVectorsY; j++) {
25.       // fieldTransparency, xField, yField, magnitude, theta, maxdist, countCharges
26.       vectors[i][j] = new Field(fieldTransparency, i*distance, j*distance, magnitude, theta, maxdist, countCharges);
27.     }
28.   }
29. }
30. void draw() {
31.   background(#DAEBF2);
32.   for (int k = 0; k < numCharges; k++) {//these loops populate the 2D array, each element of this array is an object and each object is a vector
33.     charge[k].move();
34.     charge[k].display();
35.   }
36.   for (int i = 0; i < numVectorsX; i++) {
37.     for (int j = 0; j < numVectorsY; j++) {
38.       for (int k = 0; k < numCharges; k++) {
39.         vectors[i][j].calculateField();
40.         vectors[i][j].update(charge[k].x, charge[k].y, charge[k].diameter, charge[k].minChargediameter, charge[k].maxChargediameter);//puts the fields x, y etc. from the object 'charge' into the object 'vectors', there they are set equal to targetX, targetY, etc. which is where the field points to
41.         vectors[i][j].polarity(charge[k].r);//puts the field r from the object 'charge' into the object 'vectors', there it is set equal to 'pol'.
42.         //vectors[i][j].plotField();
43.       }
44.     }
45.   }
46. }
47. void mouseReleased() {
48.   if (mouseButton == CENTER) {
49.     for (int k = 0; k < numCharges; k++) {//these loops populate the 2D array, each element of this array is an object and each object is a vector
50.       charge[k].released();
51.     }
52.   }
53. }
54. class Electrons {
55.   float x, y, r, g, b, transparency, diameter, minChargediameter, maxChargediameter;
56.   int count;
57.   //Constructor
58.   Electrons(float xpos, float ypos, float rpos, float gpos, float bpos, float trans, int countpos, float diameterpos, float minChargediameterpos, float maxChargediameterpos) {
59.     x = xpos;
60.     y = ypos;
61.     r = rpos;
62.     g = gpos;
63.     b = bpos;
64.     transparency = trans;
65.     count = countpos;
66.     diameter = diameterpos;
67.     minChargediameter = minChargediameterpos;
68.     maxChargediameter = maxChargediameterpos;
69.   }
70.   void move() {
71.     if (((dist(mouseX, mouseY, x, y))<(diameter/2))&&(mousePressed == true)) {//tests to see if mouse is on charge
72.       if (mouseButton == LEFT) {
73.         x = mouseX;
74.         y = mouseY;
75.       }
76.       else if (mouseButton == RIGHT) {//dragging mouse toward centre decreases size of charge
77.         if (((dist(mouseX, mouseY, x, y))-(dist(pmouseX, pmouseY, x, y)))>(0)) {
78.           if (diameter < maxChargediameter) {//prevents diameter getting too big, max diameter is 400
79.             diameter = diameter + 5; //increases size of diameter
80.             transparency += 0.5;
81.           }
82.         } //dragging mouse away from center increases size of charge
83.         else if (((dist(mouseX, mouseY, x, y))-(dist(pmouseX, pmouseY, x, y)))<(0)) {
84.           if (diameter > minChargediameter) {//prevents diameter getting too small and circle disappearing, min diameter is 20
85.             diameter = diameter - 5; // decreases size of diameter
86.             transparency -= 0.5;
87.           }
88.         }
89.       }
90.     }
91.   }
92.   void display() {
93.     fill(r, g, b, transparency);//fills the charge with colours red, green, blue
94.     ellipse(x, y, diameter, diameter);//draws the charge
95.   }
96.   void released() {
97.     if (((dist(mouseX, mouseY, x, y))<(diameter/2))) {//tests to see if mouse is on charge
98.       count = (count + 1) % 2;
99.       if (count == 1) {//sets colour to blue once
100.         r = 0;
101.         b = 255;
102.       }
103.       else if (count == 0) {//set colour red to blue
104.         r = 255;
105.         b = 0;
106.       }
107.     }
108.   }
109. }
110. class Field {
111.   float fieldTransparency, xField, yField, magnitude, theta, maxdist, countCharges;
112.   //Constructor
113.   Field(float fieldTransparencypos, float xFieldpos, float yFieldpos, float magnitudepos, float thetapos, float maxdistpos, int countChargespos) {
114.     fieldTransparency =fieldTransparencypos;
115.     xField = xFieldpos;
116.     yField = yFieldpos;
117.     magnitude = magnitudepos;
118.     theta = thetapos;
119.     maxdist = maxdistpos;
120.     countCharges = countChargespos;
121.   }
122.   void calculateField() {
123.     float theta = atan((targetY-yField)/(targetX-xField));//(targetX,targetY) coordinates of the charges. (xField,yField) coordinates of point at which vector is defined.
124.     float d = (sqrt(pow(targetY-yField, 2) + pow(targetX-xField, 2)));//should be 1/r^2 but not practical here
125.     if (targetX < xField) {//without this the vectors on the left of screen will point away from charge and vectors on right of screen toward it. All should point away or toward it
126.       theta += PI;
127.     }
128.     if (pol == 0) {//if 'pol' is 0 then r = 0 in charge.released and so charge is blue and positive
129.       theta += PI; //points the field away from the charge position for a positive charge
130.     }    
131.     float maxFieldstrength, minFieldstrength = 0;
132.     float newVectorlengthmin = 10, newVectorlengthmax = 35;
133.     maxFieldstrength = map(fieldStrength, minDiameter, maxDiameter, newVectorlengthmin, newVectorlengthmax);//maps the fieldStrength, which is the diameter of the charge, from the max and mix charge diameter to the max and min charger length
134.     if (d > maxFieldstrength) {
135.       magnitude = map(d, 0, maxdist, maxFieldstrength, minFieldstrength);//the second last value is the maximum length of a vector. 2nd last value should a min and last a max value, inverting them puts longest vectors near charge
136.       fieldTransparency = map(d, 0, maxdist, 205, -20);
137.     }
138. /*    countCharges = (countCharges + 1) % numCharges;
139.     if (countCharges != 0) {
140.       fieldTransparency += fieldTransparency;
141.       theta += theta;//sums theta
142.       magnitude += magnitude;//sums theta
143.     }
144.     if (countCharges == 0) {
145.       fieldTransparency = fieldTransparency/numCharges;//calculates average
146.       theta = theta/numCharges;//calculates average
147.       magnitude = magnitude/numCharges;//calculates average
148. */
149.       stroke(1, fieldTransparency);
150.       fill(0, 0, 0);
151.       pushMatrix();
152.       translate(xField, yField);
153.       rotate(theta);
154.       line(0, 0, magnitude, 0);
155.       beginShape();//this shape is the arrow heads of the vectors
156.       vertex(magnitude, -3);
157.       vertex(magnitude, 3);
158.       vertex(magnitude + 3, 0);
159.       endShape(CLOSE);
160.       popMatrix();
161.       noFill();
162.       noStroke();
163.     //} THIS BRACKET IS COMMENTED OUT
164.   }
165.   void update(float x, float y, float diameter, float minChargediameter, float maxChargediameter) {//this method transfers fields x, y, diameter, ... etc from the class Electrons to the class Field
166.     targetX = x;//x-coordinate of charge
167.     targetY = y;//y-coordinate of charge
168.     fieldStrength = diameter;
169.     minDiameter = minChargediameter;
170.     maxDiameter = maxChargediameter;
171.   }
172.   void polarity(float r) {
173.     pol = r;
174.   }
175. }

Any help would be greatly appreciated.

Thanks,

Shane

Hi,

I am trying to pass a variable called elapsedTime (line 20.) from an Ardunio sketch to a Processing sketch. I know in the Processing I can't read into a float like this. A float is 4 bytes and a read reads one byte. (line 3 of the Processing sketch)

The Ardunio code is as follows,

1. int ledTX = 12; //Receives InfraRed signal
2. int photodiodePin = 2;              // Photodiode connected to digital pin 2
3. int lastState;
4. unsigned long startTime;
5. unsigned long elapsedTime;
6. void setup() {               
7.   Serial.begin(9600);         
8.   pinMode(ledTX, OUTPUT);
9.   pinMode(photodiodePin, INPUT);    // sets the digital pin as input to read photodiode
10. }
11. void loop() {
12.   byte currentState = digitalRead(photodiodePin);
13.   digitalWrite(ledTX, HIGH);   // turn the TX Infrared LED on
14.   if(currentState == LOW && lastState == HIGH){
15.     startTime = millis();
16.   }
17.   if(currentState == HIGH && lastState == LOW){
18.     elapsedTime = millis() - startTime;
19.     Serial.println(elapsedTime);
20.     Serial.write(elapsedTime);
21.   }
22.   lastState = currentState;
23. }

The Processing code is as follows,

1. import processing.serial.*;
2. Serial port;
3. float elapsedTime;
4. void setup() {
5.   size(200, 200);
6.   background(204);
7.   noStroke();
8.   port = new Serial(this, 9600);
9. }
10. void draw() {
11.   if (0 < port.available()) {
12.     elapsedTime = port.read();
13.   }
14.   println(elapsedTime);
15. }

I was getting help with this here in the Arduino forum, but am stuck now.

Any help would be greatly appreciated.

Thanks,

Shane

Hi,

I want to create a vector field where each vector is an object and each object is an element in an array. But at the moment i am only trying to draw the tail of the vectors, I will hopefully be able to add a head to these vectors later. At the moment the sketch is only producing the tail of one vector and not the others.

1. int numVectors = 16;
2. Field[] vectors = new Field[numVectors];
3. int r, g, b;
4. void setup() {
5.   size(600, 300);
6.   int arrayx = width/5;
7.   int arrayy = height/4;
8.   smooth();
9.   noStroke();
10.   //The following 'for' loops populate the objects
11.   for (int i = 0; i < 16; i++) {//i is the object element number 
12.     for (int j = 0; j < 5; j++) {//j is for the x coordinate
13.       for (int k = 0; k < 5; k++) {//k is for the y coordinate 
14.         // x1, y1, x2, y2
15.         vectors[i] = new Field(10*j, 10*k, (10*j)+10, (10*k)+10);
16.       }
17.     }
18.   }
19. }
20. void draw() {
21.   frameRate(24);
22.   stroke(1);
23.   background(#DAEBF2);
24.   for (int i = 0; i < 16; i++) {
25.    vectors[i].plot();
26.   }
27. }
28. class Field {
29.   float x1, y1, x2, y2;
30.   //Constructor
31.   Field(float x1pos, float y1pos, float x2pos, float y2pos) {
32.     x1 = x1pos;
33.     y1 = y1pos;
34.     x2 = x2pos;
35.     y2 = y2pos;
36.   }
37.   void plot() {
38.     line(x1, y1, x2, y2);//this is just as an example
39.   }
40. }

Thanks,

shane

Hi,

I'm very new to classes but can't see why this class doesn't draw a simple line as it should.

1. Field vectors;
2. int r, g, b;
3. void setup() {
4.   size(600, 300);
5.   smooth();
6.   noStroke();
7.   // x1, y1, x2, y2
8.   vectors = new Field(100, 100, 200, 200);
9. }
10. void draw() {
11.   frameRate(24);
12.   background(#DAEBF2);
13.   vectors.plot();
14. }
15. class Field {
16.   float x1, y1, x2, y2;
17.   //Constructor
18.   Field(float x1pos, float y1pos, float x2pos, float y2pos) {
19.     x1 = x1pos;
20.     y1 = y1pos;
21.     x2 = x2pos;
22.     y2 = y2pos;
23.   }
24.   void plot() {
25.     line(x1, y1, x2, y2);//this is just as an example
26.   }
27. }

Any help would be greatly appreciated.

Thanks,

Shane

Hi,

Is writing two classes in one sketch not allowed?

I get the error:

expecting TRIPLE_DOT, found',

1. Control mouse; //Declare the object called mouse
2. Field vectors;
3. int r, g, b;
4. void setup() {
5.   size(600, 300);
6.   smooth();
7.   noStroke();
8.   //x, y, r, g, b, count, diameter... the fields
9.   mouse = new Control(300, 150, 0, 0, 255, 1, 150); //Construct the object mouse
10.   // x1, y1, x2, y2
11.   vectors = new Field(100, 100, 300, 300);
12. }
13. void draw() {
14.   frameRate(24);
15.   background(#36B5F2);
16.   mouse.move();
17.   mouse.display();
18. }
19. void vectors() {
20.   vectors.plot();
21. }
22. void mouseReleased() {
23.   if (mouseButton == CENTER) {
24.     mouse.released();
25.   }
26. }
27. class Control {
28.   float x, y, r, g, b, diameter;
29.   int count;
30.   //Constructor
31.   Control(float xpos, float ypos, float rpos, float gpos, float bpos, int countpos, float diameterpos) {
32.     x = xpos;
33.     y = ypos;
34.     r = rpos;
35.     g = gpos;
36.     b = bpos;
37.     count = countpos;
38.     diameter = diameterpos;
39.   }
40.   void move() {
41.     if (((dist(mouseX, mouseY, x, y))<(diameter/2))&&(mousePressed == true)) {//tests to see if mouse is on charge
42.       if (mouseButton == LEFT) {
43.         x = mouseX;
44.         y = mouseY;
45.       }
46.       else if (mouseButton == RIGHT) {//dragging mouse toward centre decreases size of charge
47.         if (((dist(mouseX, mouseY, x, y))-(dist(pmouseX, pmouseY, x, y)))>(0)) {
48.           diameter = diameter + 5; //increases size of diameter
49.         } //dragging mouse away from center increases size of charge
50.         else if (((dist(mouseX, mouseY, x, y))-(dist(pmouseX, pmouseY, x, y)))<(0)) {
51.           if (diameter > 20) {//prevents diameter getting too small and circle disappearing
52.             diameter = diameter - 5; // decreases size of diameter
53.           }
54.         }
55.       }
56.     }
57.   }
58.   void display() {
59.     fill(r, g, b);//fills the circle with colours red, green, blue
60.     ellipse(x, y, diameter, diameter);
61.   }
62.   void released() {
63.     if (((dist(mouseX, mouseY, x, y))<(diameter/2))) {//tests to see if mouse is on charge
64.       count = (count + 1) % 2;
65.       if (count == 1) {//sets colour to blue once
66.         r = 0;
67.         b = 255;
68.       }
69.       else if (count == 0) {//set colour red to blue
70.         r = 255;
71.         b = 0;
72.       }
73.     }
74.   }
75. }
76. class Field {
77.   float x1, y1, x2, y2;
78.   //Constructor
79.   Control(float x1pos, float y1pos, float x2pos, float, y2pos) {
80.     x1 = x1pos;
81.     y1 = y1pos;
82.     x2 = x2pos;
83.     y2 = y2pos;
84.     void vectors() {
85.       line(x1, y1, x2, y2);//this is just as an example
86.     }
87.   }

Thanks,

Shane

Hi,

I've been examining an example in the reference http://processing.org/learning/topics/arraylistclass.html which creates and destroyes element objects in an array.

I see there are three methods: move(), finished() and display() but what about .remove which seems to me a method but isn't in the class? Is this a built in function of some sort? Where can I read about this in the reference and also the 'add' in  balls .add(new Ball(mouseX, mouseY, ballWidth));

Thanks,

Shane

Hi,

I am trying to create a sketch that does the following:

LEFT mouse button allows circle to be moved

RIGHT mouse button allows circle size to change when moving toward and away from centre

CENTRE mouse button changes colour of circle from red to blue. A second click should bring it back to its previous fill colour. This last thing is what I am stuck on.

I would very much appreciate if anyone has any ideas on how this can be done.

1. float x = 300, y = 150, diameter=100;
2. void setup() {
3.   size(600, 300);
4.   stroke(1);
5. }
6. void draw() {
7.   frameRate(24);
8.   background(#36B5F2);
9.   fill(255);
10.   if (((dist(mouseX, mouseY, x, y))<(diameter/2))&&(mousePressed == true)) {
11.     if (mouseButton == LEFT) {
12.       x = mouseX;
13.       y = mouseY;
14.     }
15.     else if (mouseButton == RIGHT) {
16.       if (((dist(mouseX, mouseY, x, y))-(dist(pmouseX, pmouseY, x, y)))>(0)) {
17.         diameter++;
18.       }
19.       else if (((dist(mouseX, mouseY, x, y))-(dist(pmouseX, pmouseY, x, y)))<(0)) {
20.         diameter--;
21.       }
22.     }
23.     else if (mouseButton == CENTER) {
24.       fill(#FF0000);//red
25.     }
26.     else if (mouseButton == CENTER) {
27.       fill(#0000FF);//blue
28.     }
29.   }
30.   ellipse(x, y, diameter, diameter);
31.   fill(255);
32. }

Thanks,

Shane

I wrote a sketch using arrays and then tried to rewrite the sketch using OOP, thinking this would be less memory and processing intensive for my computer. But I am surprised that the OOP sketch is crashing.

I will post both sketches here.

1.     int numDots = 400;
2.     int amplitude = 30;
3.     float frequency = PI/30;
4.     float xPos, xPosLine;
5.     float vel = 0.01;
6.     int[]ArrayX = new int[numDots];
7.     int[]ArrayY = new int[numDots];
8.     float[]XsinVal = new float[numDots];
9.     float[]angle = new float[numDots];
10.     void setup() {
11.       size (600, 300);
12.       for (int i = 0; i < numDots; i++) {
13.         ArrayX[i] = (int) random(50, width-amplitude);
14.         ArrayY[i] = (int) random(30, height/2);
15.       }
16.     }
17.     void draw() {
18.       frameRate(24);
19.       background (33, 204, 232);
20.       noStroke();
21.       fill(24, 35, 234);
22.      
23.       for (int i = 0; i < numDots; i++) {
24.         fill(24, 35, 234);
25.        
26.         XsinVal[i] = sin(angle[i])*amplitude;
27.         ellipse(ArrayX[i] + sin(angle[i] + HALF_PI)*amplitude, ArrayY[i], 3, 3);
28.        
29.         if (xPos > ArrayX[i]) {
30.           angle[i] += frequency;
31.         }
32.        
33.         ellipse(ArrayX[i], XsinVal[i] + 230, 3, 3);
34.         stroke(250, 0, 0);
35.         fill(0);
36.         ellipse(xPos, 100, 3, 3);
37.         noStroke();
38.         fill(0);
39.        
40.         xPos += vel;
41.         stroke(0);
42.         line(35, 230, 570, 230);
43.         line(55, 180, 55, 280);
44.       }
45.     }
46.     boolean bStop;
47.     void mousePressed()
48.     {
49.       bStop = !bStop;
50.       if (bStop)
51.         noLoop();
52.       else
53.         loop();
54.     }

and the OOP sketch is

1. int numSpots = 400;
2. int amplitude = 30;
3. float frequency = PI/30;
4. //Declare and create the array
5. Spot[] spots = new Spot[numSpots];
6. void setup() {
7.   size(600, 300);
8.   smooth();
9.   noStroke();
10.   for (int i = 0; i < spots.length; i++) {
11.     float x = random(50, width-amplitude);
12.     float equilib = x;
13.     float xGlide = 10;
14.     float y = random(30, height/2);
15.     //Create each object
16.     spots[i] = new Spot(x, equilib, xGlide, y, 10, frequency);
17.   }
18. }
19. void draw() {
20.   fill(0);
21.   rect(0, 0, width, height);
22.   fill(255);
23.   for (int i = 0; i < spots.length; i++) {
24.     if (i==0) {
25.       spots[0].glide();
26.       spots[0].display();     
27.     }
28.     else {
29.       spots[i].move(); //Move each object
30.       spots[i].display(); //Display each object
31.     }
32.   }
33. }
34. class Spot {
35.   float x, y, equilib, xGlide, diameter, frequency, angle;
36.   int direction = -1;
37.   //Constructor
38.   Spot(float xpos, float equilibpos, float xGlidepos, float ypos, float dia, float fr) {
39.     x = xpos;
40.     xGlide = xGlidepos;
41.     equilib = equilibpos;
42.     y = ypos;
43.     diameter = dia;
44.     frequency = fr;
45.   }
46.   void move() {
47.     if (equilib < spots[0].x) {
48.       x = equilib + (sin(angle))*amplitude;
49.       angle += frequency;
50.       println(angle);
51.     }
52.   }
53.   void display() {
54.     ellipse(x, y, diameter, diameter);
55.   }
56.   void glide() {
57.     xGlide += 1.0;
58.     x = xGlide;
59.   }
60. }
61. boolean bStop;
62. void mousePressed()
63. {
64.   bStop = !bStop;
65.   if (bStop)
66.     noLoop();
67.   else
68.     loop();
69. }

Does anyone have any ideas why this might be? Is there something particularly inefficient about my OOP sketch?

Thanks,

Shane

Hi,

I am having a problem with an OOP. Each object should have a different xRand value but this is not happening.

Does anyone have any ideas.

Thanks,

Shane

1. int numSpots = 2;
2. int amplitude = 30;
3. float frequency = PI/24;
4. float angle;
5. float x, xRand, y;
6. //Declare and create the array
7. Spot[] spots = new Spot[numSpots];
8. void setup() {
9.   size(600, 300);
10.   smooth();
11.   noStroke();
12.   for (int i = 0; i < spots.length; i++) {
13.     x = random(50, width-amplitude);
14.     xRand = x;
15.     y = random(30, height/2);
16.     //Create each object
17.     spots[i] = new Spot(x, xRand, y, 15, frequency);
18.   }
19. }
20. void draw() {
21.   //frameRate(24);
22.   fill(0);
23.   rect(0, 0, width, height);
24.   fill(255);
25.   for (int i = 0; i < spots.length; i++) {
26.     spots[i].move(); //Move each object
27.     spots[i].display(); //Display each object
28.   }
29. }
30. class Spot {
31.   float x, y, diameter, frequency;
32.   int direction = -1;
33.   //Constructor
34.   Spot(float xpos, float xRandpos, float ypos, float dia, float fr) {
35.     x = xpos;
36.     xRand = xRandpos;
37.     y = ypos;
38.     diameter = dia;
39.     frequency = fr;
40.   }
41.   void move() {
42.     x = xRand + (sin(angle))*amplitude;
43.     angle += frequency;
44.     println(xRand);
45.   }
46.   void display() {
47.     ellipse(x, y, diameter, diameter);
48.   }
49. }
50.     boolean bStop;
51.     void mousePressed()
52.     {
53.       bStop = !bStop;
54.       if (bStop)
55.         noLoop();
56.       else
57.         loop();
58.     }

Hi,

I know I posted on this 10 months ago, but does anyone know how to stop the blinking caret (cursor) in the Processing IDE?

I can never understand why blinking is the default for so many editors.

I opened C:\Users\...\AppData\Roaming\Processing\preferences.txt

and searched for editor.caret.blink but there no such thing in this file.

Is there any other way to do this?

Thanks,

Shane

Hi,

In this programme all spots have the same x-position. I would like them to oscillate about random x-positions. But that not working?

1. int numSpots = 4;
2. int amplitude = 30;
3. float frequency = PI/120;
4. float angle;
5. //Declare and create the array
6. Spot[] spots = new Spot[numSpots];
7. void setup() {
8.   size(600, 300);
9.   smooth();
10.   noStroke();
11.   for (int i = 0; i < spots.length; i++) {
12.     float x = random(50, width-amplitude);
13.     float y = random(30, height/2);
14.     //Create each object
15.     spots[i] = new Spot(x, y, 3, frequency);
16.   }
17. }
18. void draw() {
19.   fill(0, 12);
20.   rect(0, 0, width, height);
21.   fill(255);
22.   for (int i = 0; i < spots.length; i++) {
23.     spots[i].move(); //Move each object
24.     spots[i].display(); //Display each object
25.   }
26. }
27. class Spot {
28.   float x, y, diameter, frequency;
29.   int direction = -1;
30.   //Constructor
31.   Spot(float xpos, float ypos, float dia, float fr) {
32.     x = xpos;
33.     y = ypos;
34.     diameter = dia;
35.     frequency = fr;
36.   }
37.   void move() {
38.     x =+ (sin(angle) + HALF_PI)*amplitude;
39.     angle += frequency;
40.   }
41.   void display() {
42.     ellipse(x, y, diameter, diameter);
43.   }
44. }

Line 38 is I think where the problem is.

I am new to OOP so any help would be greatly appreciated.

Thanks,

Shane

Hi,

Is it possible to use import processing.pdf.*; to merge several pdf files, not created in processing, into one pdf document?

Thanks,

Shane

Hi,

In the following simple sound wave simulation the compression lags behind the wave slightly, by about 1/8 of a wavelength. Is there any smple way to correct this? I've tried but only been able to move the wave left a bit but that's not correct.

1. int numDots = 400;
   
2. int amplitude = 30;
   
3. float frequency = PI/30; //
4. float increment = 1;
   
5. float xPos, xPosLine;
   
6. float vel = 0.01;
   
7. float xIncr = (width-50-amplitude)/numDots;
   
8.  int[]ArrayX = new int[numDots];
   
9. int[]ArrayY = new int[numDots];
   
10. float[]XsinVal = new float[numDots];
    
11. float[]angle = new float[numDots];
    
12. void setup() { size (600, 300);
    
13. for (int i = 0; i < numDots; i++) {
    
14. ArrayX[i] = (int) random(50, width-amplitude);
    
15. ArrayY[i] = (int) random(30, height/2);
    
16.  }
    
17. }
    
18. void draw() { frameRate(24);
    
19.  background (33, 204, 232);
    
20. noStroke();
    
21.  fill(24, 35, 234);
    
22. for (int i = 0; i < numDots; i++) {
    
23. XsinVal[i] = sin(angle[i])*amplitude;
    
24. ellipse(ArrayX[i] + XsinVal[i], ArrayY[i], 3, 3);
    
25.  if (xPos > ArrayX[i]) {
    
26.  angle[i] += frequency;
    
27. }
    
28. ellipse(ArrayX[i], XsinVal[i] + 230, 3, 3);
    
29.  stroke(250, 0, 0);
    
30.  fill(0);
    
31. ellipse(xPos, 100, 3, 3);
    
32. noStroke(); fill(0);
    
33. xPos += vel;
    
34. fill(24, 35, 234);
    
35. }
    
36. }
    
37. boolean bStop;
    
38. void keyPressed() {
    
39. bStop = !bStop;
    
40. if (bStop) noLoop();
    
41. else loop();
    
42. }
    

Thanks,

Shane

Hi,

While trying to run the following code I get the error

The function mouseOverRect() does not exist.

1. import processing.serial.*;
2. Serial port;
3. void setup() {
4.   size(200, 200);
5.   noStroke();
6.   frameRate(10);
7.  
8.   port = new Serial(this, 9600);
9. }
10. void draw() {
11.   background(255);
12.   if (mouseOverRect() == true) { 
    
13.     fill(204);             
    
14.     myPort.write('H');         
    
15.   }
16.   else {                       
    
17.     fill(0);                   
    
18.     myPort.write('L');             
    
19.   }
20.   rect(50, 50, 100, 100);        
    
21. }

I can't see any errors. Line 12 seems correct to me.

Thanks,

Shane

I am starting to think I have a fundamental misunderstanding of how sin() works.

e.g. the following code (just lines 12 and 14 are of interest here)

1. float XsinVal, angle, frequency = PI;
2. int XequiPos = 100; //the x-coordinate of the equilibrium position
3. int YequiPos = 100; //the y-coordinate of the oscillation
4. int amplitude = 50;
5. void setup() {
6.   size (300, 300);
7. }
8. void draw() {
9.   background (127);
10.   stroke(0);
11.   fill(0);                      
12.   XsinVal = sin(radians(angle))*amplitude;
13.   ellipse(XequiPos + XsinVal, YequiPos, 3, 3);
14.   angle -= frequency;
15. }

The first time through the draw() function, the angle is, I think 0 so sin(0)*amplitude = 0*50 = 0

Next time through and the angle is now -PI so sin(-PI)*amplitude = 0*50 = 0

And the angle becomes -2*PI and so sin(-2*PI)*amplitude = 0*50 = 0

and so on....

But how does this allow for the other value? It seems to me that the code should only give values of 0.

Thanks,

Shane

Hi,

I am trying to simulate how particles behave in a sound wave.

I have a random array of dots which oscillate horizontally. But I'd like the oscillation of each to only begin when their x-coordinate is the same as that of a red dot which travels horizontally across the screen.

The code for the dots all oscillating together is,

1. int numDots = 10;
2. float x, angle, frequency = PI;
3. float xpos;
4. float vel = 0.1;
5. int[]ArrayX = new int[numDots];
6. int[]ArrayY = new int[numDots];
7. void setup() {
8.   size (600, 300);
9.   for (int i = 0; i < numDots; i++) {
10.     ArrayX[i] = (int) random(0, width); 
11.     ArrayY[i] = (int) random(0, height);
12.   }
13. }
14. void draw() {
15.   background (127);
16.   stroke(0);
17.   fill(0);                      
18.   for (int i = 0; i < numDots; i++) {
19.     x = sin(radians(angle))*50;
20.     ellipse(ArrayX[i]+x, ArrayY[i], 3, 3);
21.     angle -= frequency/32;
22.     noStroke();
23.     fill(250, 0, 0);
24.     ellipse(xpos, 100, 5, 5);
25.     stroke(0);
26.     fill(0);
27.     xpos += vel;
28.   }
29. }

and to try to get them to only oscillate when the red dot passes using the 'if' statement on line 20:

1. int numDots = 10;
2. float x, angle, frequency = PI;
3. float xpos;
4. float vel = 0.1;
5. int[]ArrayX = new int[numDots];
6. int[]ArrayY = new int[numDots];
7. void setup() {
8.   size (600, 300);
9.   for (int i = 0; i < numDots; i++) {
10.     ArrayX[i] = (int) random(0, width); 
11.     ArrayY[i] = (int) random(0, height);
12.   }
13. }
14. void draw() {
15.   background (127);
16.   stroke(0);
17.   fill(0);                      
18.   for (int i = 0; i < numDots; i++) {
19.     angle -= frequency/32;
20.     if (xpos==ArrayX[i]) {
21.       x = sin(radians(angle))*50;
22.       ellipse(ArrayX[i]+x, ArrayY[i], 3, 3);
23.     }
24.     noStroke();
25.     fill(250, 0, 0);
26.     ellipse(xpos, 100, 5, 5);
27.     stroke(0);
28.     fill(0);
29.     xpos += vel;
30.   }
31. }

 
I don't know why the array of dots can't be seen in the second code.

I'd really appreicate any help.

Thanks,

Shane

Hi,

I'm trying to create a random array of ellipses. But I want to save athe coordinates of each in an array. I want this array only to be generated once within draw() and then to be able to use that array again with in draw.

Below is my attempt,
Any help would be greatly appreciated.

Thanks,

Shane

Hi,

I have four dots oscillating horizontally. I am trying to get them to each oscillate a quarter wave out of phase with the next one.

Here's the basic sketch:

1. float x, angle;
   
   void setup() {
     size (600, 400);
   }
   void draw() {
     background (127);
     noStroke();
     fill(0);
   
     for (int i=1; i<5; i++) {
       x = sin(radians(angle))*50;
       ellipse (x + i*100, 100, 5, 5);
       angle -= PI/4;
     }
   }
   

Here's my attempt to get the dots to oscillate out of phase.

1. float x, angle, phi;
   
   void setup() {
     size (600, 400);
   }
   void draw() {
     background (127);
     noStroke();
     fill(0);
   
     for (int i=1; i<5; i++) {
       x = sin(radians(angle))*50;
       ellipse (x + i*100 + phi, 100, 5, 5);
       angle -= PI/4;
       phi += PI/8;
     }
   }
   

This gives weird behaviour.

Any help would be greatly appreciated.

Thanks,

Shane

Hi,

I'm trying to input two numbers and have the program sum them. But I am unable to get the program to allow me to input the second number.

Does anyone know what I am doing wrong?

Thanks,

1. void setup()
   {
     size(500, 200);
     background(255);
     fill(0);
     PFont f = createFont("Verdana", 16);
     textFont(f);
   }
   
   void draw()
   {
     noLoop();
     text("Type a number to be summed:", 10, 20);
   }
   
   void keyReleased()
   {
     int number1 = int(key) - int('0');
     text(number1 + "+", 270, 20);
     if (number1 != '0') {
       int number2 = int(key) - int('0');
       text(number2, 293, 20);
       int sum = number1 + number2;
       text("=", 307, 20);
       text(sum, 322, 20);
     }
       loop();
   }
   

Hi,

I'm having a little difficulty creating a pdf. All I get is a white background.

One other thing, I've seen people upload code this this forum with lines numbered. How is that done?

Any help would be greatly appreciated.

Thanks,

1. import processing.pdf.*; // Import PDF code
   
   int cols = 5;
   int rows = 10;
   int xn0 = 1;
   int yn0 = 1;
   float y = 1, y1;
   float h = 0.1;
   float[][] myArray = new float[cols][rows]; // declares array
   
   void setup() {
     size(400, 400);
     // size(400, 400, PDF, "Euler.pdf");
     background(255);
     fill(0);
     populateArray();
     readArray();
   }
   
   void draw() {
     noLoop();
     pushMatrix();
     translate(width/2 + 52, height/2 + 55);
     line(-100, 0, 100, 0);
     line(0, 100, 0, -100);
     scale(60);
     strokeWeight(1/10);
     line(-0.05, -1, 0.05, -1);
     line(1, -0.05, 1, 0.05);
     popMatrix();
     text("(0,1)", width/2 + 22, height/2 - 5);
     text("(1,0)", width/2 + 102, height/2 + 72
       );
     pushMatrix();
     translate(width/2 + 52, height/2 + 55);
     scale(60);
     for (int j = 0; j < rows - 1; j++) {
       stroke(0, 0, 255);
       int i = 1;
       line(myArray[i][j], -myArray[i+1][j], myArray[i][j+1], -myArray[i+1][j+1]);
       ellipse(myArray[i][j], -myArray[i+1][j], 0.05, 0.05);
     }
   
     // Graph original function y(x)=(x^4 + 3)/4x
     for (float x = 1.0; x < 2.5; x += 0.01) {
       y = (pow(x, 4) + 3)/4*x;
       stroke(255, 0, 0);
       ellipse(x, -y, 0.01, 0.01);
       // point(x, -y);
     }
     popMatrix();
   }
   
   void keyPressed() {
     if (key == 'B' || key == 'b') {
       beginRecord(PDF, "Euler.pdf");
     }
     else if (key == 'E' || key == 'e') {
       endRecord();
       exit();
     }
   }
   
   void populateArray() {
     for (int j = 0; j < rows; j++) {
       for (int i = 0; i < cols; i++) {
         if (j==0);
         {
           myArray[1][0] = xn0;
           myArray[2][0] = yn0;
         }
         if (i==0) // first column
         {
           myArray[i][j] = j+1;
         }
         if ((i==1) && (j!=0)) // xn values, adds h to the previous xn value
         {
           myArray[i][j] = h + myArray[i][j-1];
         }
         if ((i==2) && (j!=0)) // yn values, previous yn value
         {
           myArray[i][j] = myArray[i+2][j-1];
         }
         if (i==3) // fn values, fn = (xn^3 - yn)/xn (this is the derivative dy/dx)
         {
           myArray[i][j] = (pow(myArray[i-2][j], 3) - myArray[i-1][j])/myArray[i-2][j];
         }
         if ((i==4)) // y_{n+1} values, yn+1 = yn + h*fn
         {
           myArray[i][j] = myArray[i-2][j] + h*myArray[i-1][j];
         }
       }
     }
   }
   
   void readArray() { // reads the myArray and tabulates it
     translate(-20, 20);
     for (int i = 0; i < cols; i++) {
       for (int j = 0; j < rows; j++) {
         if (j==0);
         {
           text(myArray[i][j], ((i+1)*40), ((j+1)*20)+20);
         }
       }
     }
     stroke(0, 0, 0);
     text("Euler method: dy/dx=(x^3-y)/x)", 40, -3);
     text("n", 50, 15);
     text("xn", 90, 15);
     text("yn", 130, 15);
     text("fn", 170, 15);
     text("y_{n+1}", 200, 15);
     line(40, 23, 247, 23);
     line(80, 5, 80, (rows*20)+30);
   }
   
   

Hi,

The following code produces an array of numbers. But there seem to be numbers over numbers and I am not sure how to fix this.

I think the problem may be to do with the fact that the two functions are called from inside draw() and so are endlessly running. I tried placing the call to them outside of this but inside draw() seems to be the only place i can get them to work.

Any help would be greatly appreciated.

Thanks,

Shane

1. int cols = 5;
   int rows = 10;
   int xn0 = 1;
   int yn0 = 1;
   float h = 0.1;
   float[][] myArray = new float[cols][rows]; // declares array
   
   void setup() {
     size(400, 400);
     background(255);
     fill(0);
   }
   
   void draw() {
     populateArray();
     readArray();
   }
   
   void populateArray() {
     for (int i = 0; i < cols; i++) {
       for (int j = 0; j < rows; j++) {
         if (j==0);
         {
           myArray[1][0] = xn0;
           myArray[2][0] = yn0;
         }
         if (i==0) // first column
         {
           myArray[i][j] = j+1;
         }
         if ((i==1) && (j!=0)) // xn values, adds h to the previous xn value
         {
           myArray[i][j] = h + myArray[i][j-1];
         }
         if ((i==2) && (j!=0)) // yn values, previous yn value
         {
           myArray[i][j] = myArray[i+2][j-1];
         }
         if (i==3) // fn values, fn = (xn^3 - yn)/xn
         {
           myArray[i][j] = (pow(myArray[i-2][j], 3) - myArray[i-1][j])/myArray[i-2][j];
         }
         if ((i==4)) // y_{n+1} values, yn+1 = yn + h*fn
         {
           myArray[i][j] = myArray[i-2][j] + h*myArray[i-1][j];
         }
       }
     }
   }
   
   void readArray() {
     for (int i = 0; i < cols; i++) {
       for (int j = 0; j < rows; j++) {
         if (j==0);
         {
           text(myArray[i][j], ((i+1)*40), ((j+1)*20)+20);
         }
       }
     }
     text("n", 50, 15);
     text("xn", 90, 15);
     text("yn", 130, 15);
     text("fn", 170, 15);
     text("y_{n+1}", 210, 15);
     line(40, 23, 250, 23);
     line(80, 5, 80, (rows*20)+30);
   }
   

Hi,

I'm trying to control a variable inside draw() with data from the serial port. The serial port is connected to an Arduino with a simple potentiometer circuit.

I can read in from the serial port to a variable called inByte. But then how do I work with that inside draw()? The code is below.

Any help would be greatly appreciated.

Thanks,

Shane

1. import processing.serial.*;
   
   Serial myPort;        // The serial port
   
   void setup () {
     size(400, 300);       
     println(Serial.list());
     myPort = new Serial(this, Serial.list()[0], 9600);
     myPort.bufferUntil('\n');
   }
   void draw () {
2.     fill(0, 12);
       line(inByte, 0, width, height);
   }
   
   void serialEvent (Serial myPort) {
     String inString = myPort.readStringUntil('\n');
   
     if (inString != null) {
       inString = trim(inString);
       float inByte = float(inString);
       inByte = map(inByte, 0, 1023, 0, 255);
   
     }
   }
   

Why does the following not work to grow an ellipse?

1. void setup() {
     size(200, 200);
     smooth();
   }
   void draw() {
     background(255);
     scale(1.2, 1.2);
     ellipse(20, 20, 20, 20);
   }
   
   

Any help would be greatly appreciated,

Thanks,

Shane

Hi,

I have seen how processing can be used to to export a frame or image to pdf but is it possible to make a pdf of data which would normally be output to the console?

For example of something simple like,

for(int i = 1; i < 11; i++){
 println(i);
}

Any help would be greatly appreciated,

Thanks,

Shane

Hi, 

Can Processing be installed on a USB so that it can be run on a computer where the user does not have admin access?

Any help would be greatly appreciated,

Shane