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Using the Map function

In Processing, you can use the map function to convert an input value that is usually between a certain range, to another value between a new range.

The map function takes 5 arguments:

  • The input value (the one you want to convert);
  • The minimum that value could have.
  • The maximum that value could have (the end point of the range).
  • The start of the new range we want our value to be in.
  • The end of the new range we want our value to be in.

For example, if we want to use the x position of the mouse to impact the color of an ellipse within the width of a sketch, we would use the map function that way:

int grey = map(mouseX, 0, width, 0, 255);
fill(grey);
ellipse(0,0,20,20);

The value we use to have the x position of the mouse is mouseX which is within the range 0 and width. But colors are usually between 0 and 255 so we need to convert the value we get from mouseX to a new range between 0 and 255.