Error - Mapping value affects the other values

blyk

I have been mapping to write a code when I stumble upon this problem. Here in the code, line 11, I am mapping the i from 2-7 --> 0, 50 for R. Ideally this mapping shouldn't affect the value of i but it is affecting.

The problem -> when I map i from 0-7 it works and the letter "A" doesn't rotate but when I map i from 2-7 it affects the value of i and "C" is the letter which doesn't rotate, ideally it should be "A" no matter how do I map i for R

    String[] s = {
      "A", "B", "C", "D", "E", "F", "G"
    };  
    void setup() {
      size(300, 300);
    }
    int k=0;
    void draw() {
      background(-1);
      for (int i=0; i<7; i++) {
        float R = map(i, 2, 7, 0, 50);
        float ang = i*360/7;
        float x = width/2+R*cos(radians(ang)+radians(k));
        float y = height/2+R*sin(radians(ang)+radians(k));
        // println(i);
        //    if (i<4) {
        fill(0);
        text(s[i], x, y);
        //    } else {
        //      fill(0);
        //      ellipse(x, y, 5, 5);
        //    }
      }
      k++;
    }

koogs

println(map(0, 2, 7, 0, 50)); // -20
println(map(1, 2, 7, 0, 50)); // -10

this is a bit unexpected, i guess, but perfectly valid. you can think of the arguments as defining a line that goes through 2, 0 and 7, 50 BUT one that is defined outside of the range x=2 to 7 - the line carries on from -infinity to +infinity.

blyk

@koogs thank for the reply :)

my concern wasn't the value of R but i. It is somehow getting affected by mapping function. For instance, if you run the code with line 11 as R = map(i,0,7,0,50); then the letter "A" remain in the center whereas when I change the line 11 to R = map(i,2,7,0,50); then the letter "C" remain in the center but ideally "A" should be in the center. What I am is not able to understand is that the when I am mapping the values for R why the value of i is changing ?

koogs

it isn't.

println is your friend.

koogs

R is changing. with 2, 7 you have a negative R for a and b and c has 0 radius. that's why c isn't moving and a and b are.

with 0, 7 a has an R of 0 which is why it stays still.

blyk

@koogs I am a real retard b-( I don't know what I was thinking before asking this stupid question. I am really sorry :(

And thank you soooo much for the help :) :) :)