var xT = 20;
var yT = 20;
var W = 500;
var H = 500;

var backgroundColor = 'rgb(200,200,200)';


tributary.init = function(ctx) {
};
tributary.run = function(ctx,t) {
    tributary.clear(); //helper function to clear the canvas

  	this.axisAndBackground(ctx);
};

//drawing functions

tributary.axisAndBackground = function(ctx){
  	ctx.fillStyle = backgroundColor;
  	this.drawRectT(ctx, 0, 0, 1, 1);
}



//drawing primitves

tributary.drawRectT = function(ctx, x, y, w, h){
  ctx.fillRect(x*W+xT, y*H+yT, w*W, h*H);
}
tributary.lineT = function(ctx, x0, y0, x1, y1){
  this.moveToT(x0, y0);
  this.lineToT(x1, y1);
}
tributary.moveToT = function(ctx, x, y){
  ctx.moveTo(x*W+xT, y*H+yT);
}
tributary.lineToT = function(ctx, x, y){
  ctx.lineTo(x*W+xT, y*H+yT);
}