CODEWITHSUNDEEP
javarotationdrawinglineprocessing
praxmon
praxmon

Reputation: 5121

Line rotation: Processing

The code given below is used for rotating a line about the center of the window. The thing is the output of the program is weird. Where am I going wrong? I am including code and the different outputs to illustrate the problem.

void setup()
{
  size(500,500);
  translate(width/2, height/2);
  line(0,0,200,0);
  line(0,0,0,200);
  line(0,0,-200,0);
  line(0,0,0,-200);
  pushMatrix();
  float x=200*cos(degrees(30));
  float y=200*sin(degrees(30));
  line(0,0,x,y);
  popMatrix();
}

enter image description here

When changing the angle to 45 I get:

enter image description here And when I change the angle to 60 I get:

enter image description here

How are the angles working here?

Upvotes: 1

Views: 1844

Answers (1)

user2468700
user2468700

Reputation: 974

You used the wrong function to get radians.

radians(angle) converts degrees --> radians;

degrees(angle) converts radians --> degrees.

The following code works well:

float x, y, radius;

void setup () {
  size(500, 500);
  radius = 200;
}

void draw () {
  background(255);

  pushMatrix();
  translate(width/2, height/2);
  line(-200, 0, 200, 0);
  line(0, -200, 0, 200);

  x = radius*cos(radians(30));
  y = radius*sin(radians(30));

  line(0, 0, x, y);
  popMatrix();
}

Let me clarify another thing:

Transformations are cumulative and apply to everything that happens after and subsequent calls to the function accumulates the effect. [...] If translate() or rotate() is called within draw(), the transformation is reset when the loop begins again. – P5 Reference

pushMatrix() and popMatrix() are useful to encapsulate matrix transformations you don't want to apply to the whole code. They are useless in your example.

Upvotes: 3

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