fix HiDPI issue

[burner-account]

• as of HiDPI broken, possible workaround inside #159
• switch to glfw 3.3
• retrieving scale via (*glfw.Window).GetContentScale()
• scaling mouse positions accordingly

[burner-account]

If this one is accepted, you will need to patch the g3nd raycasting demo to obey UI scaling.

func (t *Raycast) onMouse(a *app.App, ev interface{}) {

	// Convert mouse coordinates to normalized device coordinates
	mev := ev.(*window.MouseEvent)
	width, height := a.GetSize()
	scx, scy := a.GetScale()
	x := 2*(mev.Xpos/(float32(width) / scx)) - 1
	y := -2*(mev.Ypos/(float32(height) / scy)) + 1

       // that's it

[wolfgarnet]

Why the extra lines?

[burner-account]

Lack of coffee... definitly not intention.

[wolfgarnet]

Tentative approval from me.

[danaugrs]

Thanks @burner-account and @wolfgarnet. There have been a lot of changes since this was created, so I'll close it.
I see you set the following GLFW flag, which we don't set currently:

glfw.WindowHint(glfw.ScaleToMonitor, glfw.True)

Did it have an impact in fixing HDPI?

[burner-account]

glfw.WindowHint(glfw.ScaleToMonitor, glfw.True)

Did it have an impact in fixing HDPI?

Quite frankly, i do not remember. Might have been only relevant to my system setup without me knowing it.
A quick web search got me the following description:

"ScaleToMonitor - Specifies whether the window content area should be resized based on the monitor current scale of any monitor it is placed on. This includes the initial placement when the window is created."

From my current point of view this should be something configurable in the product using g3n/engine.