Using PVector to plot coordinates

Programming Questions

nighrage

Using PVector to plot coordinates

in Programming Questions • 2 years ago

I am trying to plot X, Y and Z coordinates on a 3D landscape using PVector. How do I go about doing this?

I am having trouble declaring X, Y and Z values and then extracting the corresponding values from a table.

Any help would be much appreciated.

Replies(7)

owaunz

Re: Using PVector to plot coordinates

2 years ago

PVectors are great.

Just use...

PVector [] jet = new PVector [256];
PVector jani = new PVector(256,256,256);

void setup(){
size(512,512,P3D);

for (int i=0;i<jet.length-1;i++){
jet[i]=new PVector(random(width),random(height),random(width));
}

}

void draw(){
background(-1);
for (int i=0;i<jet.length-1;i++){
line(jani.x,jani.y,jani.z,jet[i].x,jet[i].y,jet[i].z);

}

}

nighrage

Re: Re: Using PVector to plot coordinates

2 years ago

I am trying to plot coordinates on a 3D scatter plot, I have a vague idea of what needs to be done but just can figure how it should be done. I hope what I have written down gives you a vague idea of what I am trying to do but the problem I am not sure how it should be properly implemented.

int rowCount;

float x;

float y;

PVector[] vecs = new PVector[rowCount] ;

void setup(){
size(512,512,P3D);
// Read the data table
jdTable = new Table("jd.tsv");
rowCount = jdTable.getRowCount();

void draw()
{background(255);
for (int row=0; row<rowCount; row++) {
                float x = locationTable.getFloat(row,1);
  float y = locationTable.getFloat(row,2);
  float z = locationTable.getFloat(row,3);
  PVector(float x, float y, float z);}
}

quarks

Re: Using PVector to plot coordinates

2 years ago

I assume that jd,tsv is a file where each line has three floating point values (x/y/z) separated by tab characters. If that is the case this will load the data and store it in an array of PVector

int rowCount;
float x;
float y;
float z;
PVector[] vecs;
String[] rows;
char tab = char('\t');
void setup() {
size(512, 512, P3D);
//String[] rows = loadStrings("jd.tsv");
rows = new String[] {
" 1.1 " + tab + "2.2 "+tab+"3.3 "
};
rowCount = rows.length;
vecs = new PVector[rowCount] ;
for (int i = 0; i < vecs.length; i++) {
String[] vstrings = split(rows[i], tab);
x = Float.parseFloat(vstrings[0].trim());
y = Float.parseFloat(vstrings[1].trim());
z = Float.parseFloat(vstrings[2].trim());
vecs[i] = new PVector(x, y, z);
println(vecs[i]);
}
}
void draw(){
background(255);
for (int i=0; i < vecs.length; i++) {
// xyz coordinates are stored in
// vecs[i].x vecs[i].y vecs[i].z;
}
}

nighrage

Re: Re: Using PVector to plot coordinates

2 years ago

Thank you mate but I dont quite understand why you have used

String[] rows;
char tab = char('\t');

Would you mind explaining why?

PhiLho

Re: Using PVector to plot coordinates

2 years ago

String[] rows declares an array of strings (uninitialized, so set to null).
The second line defines a char, ie. a character. The char() call is a bit redundant since '\t' is already a char.

quarks

Re: Re: Using PVector to plot coordinates

2 years ago

You probably realised that line 11 needs to be uncommented and lines 12-14 want removing since these were for testing only. If you do this line 6 ( String[] rows;) becomes redundant and should be removed. This is better because there you only need the vecs array for use with draw()

Also if you change line 18 to
String[] vstrings = split(rows[i], '\t');
then line 7 ( char tab = char('\t');) becomes redundant and can be removed.

nighrage

Re: Using PVector to plot coordinates

2 years ago

Guys the sketch seem to run without prompting an error message but the points are not visible. Does anybody know why?

import processing.opengl.*;
int dim = 250;
int rowCount;
float x;
float y;
float z;
PVector[] vecs;
String[] rows;
char tab= char('\t');
float rotY; // Amount of rotation around y-axis.
float rotX; // Amount of rotation around the x-axis.
PFont font;
Table jdTable;
float dataMin, dataMax;
void setup()
{
size(500,500,OPENGL);
smooth();
rotY = 0;
rotX = 0;
String[] rows = loadStrings("jd2.tsv");
font = createFont( "arial", 14 );
textFont(font);
// Read the data table
jdTable = new Table("jd.tsv");
rowCount = jdTable.getRowCount();
rowCount = rows.length;
vecs = new PVector[rowCount] ;
for (int i = 0; i < vecs.length; i++) {
String[] vstrings = split(rows[i], tab);
x = Float.parseFloat(vstrings[1].trim());
y = Float.parseFloat(vstrings[2].trim());
z = Float.parseFloat(vstrings[3].trim());
vecs[i] = new PVector(x, y, z);
println(vecs[i]);
}
}
void draw()
{
background(255);
translate(width/2,height/2);
scale(1,-1,1); // so Y is up, which makes more sense in plotting
rotateY(rotY);
rotateX(rotX);
noFill();
strokeWeight(1);
stroke(0,10);
box(dim);
translate(-dim/2,-dim/2,-dim/2);
strokeWeight(2);
stroke(0);
line(0,0,0,dim,0,0);
line(0,0,0,0,dim,0);
line(0,0,0,0,0,dim);
// Draw axis labels.
textSize(25);
String axisLabel;
fill(50);
pushMatrix();
scale(1,-1,1);
axisLabel = "x-axis";
text(axisLabel,dim-textWidth(axisLabel),0,0);
axisLabel = "y-axis";
rotateZ(HALF_PI);
text(axisLabel,-dim,0,0);
axisLabel = "z-axis";
rotateZ(-HALF_PI);
rotateY(HALF_PI);
text(axisLabel,-dim,0,0);
popMatrix();
// Draw cubes.
for (int i=0; i<vecs.length; i++)
{
PVector v = vecs[i];
// cubes
noStroke();
fill( 255, 100, 100 );
pushMatrix();
translate( v.x,v.y,v.z);
box(5);
popMatrix();
}
}
void mouseDragged()//navigate around the sketch
{
rotY += (mouseX-pmouseX)*0.01;
rotX += (mouseY-pmouseY)*0.01;
}
void keyReleased()//reset sketch
{
if (key==ENTER) setup();
}

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