Another example, with sq and dist methods

Re: Another example, with sq and dist methods

Sat, 27 Mar 2010 19:24:52 +0000

Cool. A lot of functional programming in there?

Kinda, sorta. My first significant programming experience was with Lisp, and I've worked with SML some.

Re: Another example, with sq and dist methods

Sat, 27 Mar 2010 12:42:52 +0000

I do have about 30 years of experience with programming, though :)

Cool. A lot of functional programming in there?

I've cloned the source to have a look at the innards, so hopefully I'll be able to figure out commands on my
own in the future.

Feel free to continue asking about anything that you find unclear.

If you have any problems working with the source, please ask here (on the just created kojo-dev forum):
http://www.kogics.net/forum/c-110283/kojo-dev

Re: Another example, with sq and dist methods

Sat, 27 Mar 2010 09:51:44 +0000

I was thinking that this kind of generic declaration would be helpful to smooth out the learning curve a bit. I remember from my teaching days that the difference between integers and FPNs bothered my students, and the difference between floats and doubles baffled them. Still, there seems to be some pitfalls here.

I might add that I'm a bit new with Scala; I've only used it for a year or so. I do have about 30 years of experience with programming, though :)

I've cloned the source to have a look at the innards, so hopefully I'll be able to figure out commands on my own in the future.

Re: Another example, with sq and dist methods

Sat, 27 Mar 2010 03:25:24 +0000

Keep the good stuff coming.

I would think that the technique of using an implicit parameter to keep your methods generic should work with both scala 2.7 and 2.8

The 2.8 @specialize stuff might be able to make such method efficient for primitives.

fgClear() is to clear the foreground. It allows you to clear just the foreground (while keeping the background) within a Canvas animation.

An example of how to use fgClear() is available in the Samples included with Kojo:
Samples -> Early Preview -> Canvas -> Sine of an Angle

Another example, with sq and dist methods

Thu, 25 Mar 2010 09:09:01 +0000

import java.awt.Color._ def sq[A](x: A)(implicit n: Numeric[A]): A = n.times(x, x) def dist[A](x0: A, y0: A, x1: A, y1: A)(implicit n: Numeric[A]): A = { val v = n.plus(sq(n.minus(x0, x1)), sq(n.minus(y0, y1))) val r = Math.sqrt(n.toDouble(v)) if (v.isInstanceOf[Int]) r.toInt.asInstanceOf[A] else if (v.isInstanceOf[Float]) r.toFloat.asInstanceOf[A] else r.asInstanceOf[A] } clear invisible Canvas.fgClear //? val width = 200 val height = 200 // background(0) val maxDistance = dist(width/2, height/2, width, height) val distances = Seq.tabulate(width, height){ case (i, j) => dist(width/2f, height/2f, j, i)/maxDistance * 255 } for (i <- 0 until(height, 2) ; j <- 0 until(width, 2)) { val c = distances(j)(i).toInt Canvas.setPenColor(new Color(c, c, c)) Canvas.point(j, i) }