Can't use translate()

in Programming Questions • 1 year ago

I need a teacher I guess. I spent hours to find a solution to this simple problem. How to get 3 times 6 balls, spread like a fan (eventail in french).

There is the very simple code .

// get 3 times 6 balls in order

float x, y, theta, r;

int nC = 0;

void setup() {

size(600, 400);

background(255);

theta = 0.0;

r = 50 ;

}

void draw() {

noLoop();

stroke(0);

//translate(width/2, height/4);

for (int n=0;n<3;n++) {

nC = n;

choixCouleur();

//pushMatrix();

translate(width/2, height/4);

for (int i=0;i<6;i++) {

x = r*cos(theta);

y = r*sin(theta);

theta +=0.3;

ellipse(x, y, 16, 16);

}

//popMatrix();

//x += 20;

//y += 20;

//theta = 0.0;

}

void choixCouleur() {

if (nC<1) {

fill(255, 0, 0);// rouge

}

else {

if (nC<2) {

fill(0, 255, 0);// vert

}

else {

fill(0, 0, 255);// bleu

}

Replies(10)

Jesse Sco..

Re: Can't use translate()

1 year ago

You need to use your translate() within your for() ...

etiennefr..

Re: Can't use translate()

1 year ago

It doesn't work, I get only one ball has it always draw me back to the translate() position.

Or did I misunderstood ?

veeableful

Re: Can't use translate()

1 year ago

If I got your question right, here's an example implementation using rotate():

void setup() {
size(400, 400);
int numBlades = 3;
int numEllipses = 6;
int ellipseSize = 16;
for (int i = 0; i < numBlades; i++) {
pushMatrix();
translate(width/2, height/2);
rotate(2*PI/numBlades * i);
for (int j = 0; j < numEllipses; j++) {
float x = j * ellipseSize;
float y = j * sin(PI/numEllipses) * j;
ellipse(x, y, ellipseSize, ellipseSize);
}
popMatrix();
}
}

Basically, the translate() acts as the pivot point for the rotate(). Hope it helps!

etiennefr..

Re: Can't use translate()

1 year ago

It's not exactly what I wanted to do, however it helps me to better understand the way it works.

Thanks.

veeableful

Re: Can't use translate()

1 year ago

Cool! Do you think you can do what you wanted to do now? Feel free to ask questions :)

veeableful

Re: Can't use translate()

1 year ago

Hmm is this what you wanted? I missed the word eventail.

void setup() {
size(400, 400);
int numBlades = 3;
int numEllipses = 6;
int ellipseSize = 16;
float rad = 50;
for (int i = 0; i < numBlades; i++) {
pushMatrix();
translate(width/2, height/2);
rotate(PI/numBlades * i);
for(int j = 0; j < numEllipses; j++) {
pushMatrix();
rotate((PI/3) / numEllipses * j);
ellipse(rad, 0, ellipseSize, ellipseSize);
popMatrix();
}
popMatrix();
}
}

etiennefr..

Re: Can't use translate()

1 year ago

Not yet, that sort of ring, let's say, is easy to do. My english isn't very good and I'm missing the possibility to draw something to explain. So, I'll try to better explain.

Imagine a clockwork. You have a ball that starts right in the middle of the panel and goes on, step by step, to the number one. Then a second one, starting also from the middle starts and end to number two, etc. Finally you get six of them,from number one to six of your clock. Up to that level we can manage. :-)

Now the problem is that I want to have a second rank of those balls, in the same order but within a larger circle. And then a third circle, also larger. Without losing the first and the second one.

I've tried everything, translate, push and popMatrix. I always get a result but not the one I want. I must say that the usage cos and sin are'nt too familiar to me.

Thanks again for you help.

kooogy

Re: Can't use translate()

1 year ago

wider circles is just a case of increasing the radius.

get rid of the pushMatrix and popMatrix and the translation within the loop. also don't increment the angle all the time

for (int n = 0 ; n < 3 ; n++) { // 3 colours
nC = n;
choixCouleur();
for (int i = 0 ; i < 6 ; i++) { // 6 angles
theta = i * PI / 5; // from 3 to 9 o'clock
r = 30 * (n + 1); // radius is 30, 60, 90
x = r * cos(theta);
y = r * sin(theta);
ellipse(x, y, 16, 16);
}
}

kooogy

Re: Can't use translate()

1 year ago

also, all those variables, r, x, y, theta, should be local to the inner loop, there's no need for them to be global.

ditto nC - just pass n as an argument to choixCouleur()

etiennefr..

Re: Can't use translate()

1 year ago

that works perfectly when I get rid of the translate() instruction that I wasn't managed well.

Thanks for your help.

Top Reply

Response title

Attachments

New to this Portal?