Objects Disappear

OpenGL OpenGL: Basic Coding
1

Hi. Ive written a quick test app that sets up an ortho window then draws a traingle and a quad.

The problem is, when I resize or minimize the app, both objects disappear and will not return.

Here is the resize function

 
SUB mgeWindow_Resize(Width:INT, Height:INT)

' Prevent divide by zero
	IF Height = 0
		Height = 1

	ENDIF

' Set the viewport
	glViewport(0, 0, Width, Height)

	glMatrixMode(GL_PROJECTION)
	glLoadIdentity()

' Setup ortho projection
	glOrtho(-0.375, (Width - 0.375), (Height - 0.375), -0.375, -1.0, 1.0)

	glMatrixMode(GL_MODELVIEW)
	glLoadIdentity()

And the message callback is a simple

 CASE WM_SIZE
		' Resize the OpenGL viewport to match the new client area
			mgeWindow_Resize(mgeHelper_LoWord(lParam), mgeHelper_HiWord(lParam))

			RETURN 0

I cannot understand why this is happening or how to fix it. Any ideas (apologies if the code formatting is iffy).

Cheers :slight_smile:

2

Are you calling your display function when a resize occurs? If you’re not then that could be causing your problem.

3

Ive traced the error back to the HiWord function I wrote - the Loword one works fine as I checked the values they were both returning - and only this one was returning trash.

Keep in mind im not using C++.

 SUB mgeHelper_HiWord(Hi:UINT),WORD

RETURN (Hi & 0xFFFF0000 / 0x00010000)

ENDSUB
4

Hold your horses Ive fixed it :smiley:

a simple brackets addition was required

SUB mgeHelper_HiWord(Hi:UINT),WORD

RETURN ((Hi & 0xFFFF0000) / 0x00010000)

ENDSUB