// title: Sketch Pad
// author: eli.fieldsteel
// description:
// An environment in which the user can draw using the mouse.
// code:
//LET'S PAINT!
//select all and compile

var point, red, green, blue, win, view, colorTask;
var redChange, greenChange, blueChange;

//rate of change of each color component
//mess around with these values for fun
//zero results in no color change
redChange = 0.01;
greenChange = 0.015;
blueChange = 0.02;

//default starting RGB values
//these values can be changed as well
//maintain range of 0≤x≤1
red=0; green=0.33; blue=0.67;

//window creation
win = Window("FANCY ARTWORK", resizable:true, border:false);
win.fullScreen;
win.onClose = {
	if( 
		colorTask.isPlaying,
		{colorTask.stop},
		{}
	);
};

//userview creation
view = UserView(win, Window.screenBounds);
view.clearOnRefresh = false;
view.background = Color.white;

//any click sets point as current mouse location
//left-click does nothing special
//right-click clears palette
view.mouseDownAction = {
	|v, x, y, mod, butNum, clkCnt|
	point = [x,y];
	if(butNum == 1,
		{
			view.drawFunc_({nil});
			view.clearDrawing;
			view.refresh},{}
	);
};

//mouse drag redefines userview drawFunc
//Pen draws line from old point to current point
//then sets old point equal to current point
view.mouseMoveAction = {
	|v, x, y, mod|
	view.drawFunc = {
		Pen.strokeColor = Color.new(
			red.fold(0,1),
			green.fold(0,1),
			blue.fold(0,1)
		);
		Pen.width = 3;
		Pen.line(point.asPoint,x@y);
		point = [x,y];
		Pen.stroke;
		};
	win.refresh;
};

//RGB values wrap through range 0≤x<2
//and are folded into 0≤x≤1 via mouseMove function
//thus RGB values oscillate linearly, out of phase with
//one another, back and forth from 0 to 1
colorTask = Task({
	{
		red = (red + redChange)%2;
		green = (green + greenChange)%2;
		blue = (blue + blueChange)%2;
		0.05.wait; //arbitrary wait time
	}.loop;
});

//comment out for no color change
colorTask.start;

win.front;