How Can I Use drawGL?

instanceProto.draw = function (ctx) {
		var myx = this.x;
		var myy = this.y;
		var w = this.width;
		var h = this.height;
		ctx.fillStyle = "blue";
		ctx.fillRect(myx, myy, w, h);
	};

instanceProto.drawGL = function (glw) {
	};
[/code:2h5eova9]

There is not information in C3 manual ([url=https://www.construct.net/it/make-games/manuals/addon-sdk/search?q=drawGL]link[/url]). The same in C2 manual ([url=https://www.scirra.com/manual/search?q=drawGL]link 1[/url], [url=https://www.scirra.com/manual/23/runtime-functions]link 2[/url]).

instanceProto.drawGL = function(glw) {
    var q = this.bquad;
   
   glw.setColorFillMode(0,0,255,1); // colora
   glw.quad(q.tlx, q.tly, q.trx, q.try_, q.brx, q.bry, q.blx, q.bly);
};[/code:3g8azeha]

But this doesn't draw 3 blue points: they're black.
[code:3g8azeha]instanceProto.drawGL = function(glw) {
  glw.setColorFillMode(0,0,255,1);
  var a = glw.point(1,1,5,1);
  var b = glw.point(20,20,5,1);
  var c = glw.point(40,40,5,1);
};
[/code:3g8azeha]

And this code
[code:3g8azeha]instanceProto.drawGL = function(glw) {
  var x1 = glw.point(80,80,5,1);
  var x2 = glw.point(100,100,5,1);
  var x3 = glw.point(100,200,5,1);

  glw.convexPoly(x1, x2, x3);
};
[/code:3g8azeha]
gives me this error:
[code:3g8azeha]Uncaught TypeError: Cannot read property 'length' of undefined[/code:3g8azeha]

I don't undertand how I can draw lines. I can't find a line function in c2/glwrap.js

instanceProto.drawGL = function(glw) {
   var q = this.bquad;
   glw.setColorFillMode(0,0,255,1);
   glw.convexPoly([q.tlx, q.tly, q.trx, q.try_, q.brx, q.bry]);
};
[/code:305dxzse]

But, how I can draw a line? And points with color? Is this correct? Is the only way?
[code:305dxzse]
  var point = glw.quad(50, 50, 55, 50, 55, 55, 50, 55);
  var line = glw.quad(150,150,151,150,251,251,250,250);
[/code:305dxzse]

iRenderer.SetColorRgba(127,254,212, 1);
iRenderer.SetColorFillMode();
iRenderer.ConvexPoly([myx, myy, myx+w, myy, myx+w, myy+h, myx, myy+h]);
[/code:jfq526sl]

[b]runtime.js[/b]
[code:jfq526sl]
instanceProto.drawGL = function(glw) {
    var myx = this.x;
    var myy = this.y;
    var w = this.width;
    var h = this.height;
   glw.setColorFillMode(255, 255, 0, 1);
   glw.quad(myx, myy, myx+w, myy, myx+w, myy+h, myx, myy+h);
  };
[/code:jfq526sl]

But if I change 

[b]instance.js[/b] iRenderer.SetColorRgba(127, 254, 212, 1);
[b]runtime.js[/b] glw.setColorFillMode(127, 254, 212, 1);

I have a white quad.

Instead in [b]instanceProto.draw[/b] I can draw a coloured quad simply changing [i]ctx.fillStyle[/i]

[code:jfq526sl]
  // ctx.fillStyle = `rgba(255, 255, 0, 1)`;
  ctx.fillStyle = `rgba(127, 254, 212, 1)`;
  ctx.beginPath();
  ctx.moveTo(myx, myy);
  ctx.lineTo(myx+w, myy);
  ctx.lineTo(myx+w, myy+h);
  ctx.lineTo(myx, myy+h);
  ctx.closePath();
  ctx.fill();
 [/code:jfq526sl]

What's wrong with what I'm doing?