OpenGL Apps Made Easy (Skeleton OGLApp Class)

Mike Lobanovsky · **Joined:** Tue Apr 19, 2005 7:22 am **Posts:** 890

This is a very early version of an OpenGL application class that resembles simple OpenGL windows created by GLUT libraries.

It will be developed further to include more functionality like e.g. simplified message handling, primarily to deal with mouse and keyboard events.

But even now you can see that writing OGL applications may be almost as easy as writing console programs. For example, the classical colored triangle example needs only the following code:

Code:

#Uses "@|WIN32"
#Option Strict

#Include "COGLTestApp.inc"

Dim TestApp As New COGLTestApp("OpenGL Test Bench", AddressOf Render)
Center(TestApp.hWnd())
Show(TestApp.hWnd())
TestApp.Run()

Sub Render()
   glBegin(GL_TRIANGLES)
      glColor3d(1.0, 0.0, 0.0)
      glVertex2i(0, 1)
      glColor3d(0.0, 1.0, 0.0)
      glVertex2i(-1, -1)
      glColor3d(0.0, 0.0, 1.0)
      glVertex2i(1, -1)
   glEnd()
End Sub

Mike

Gerome · **Posted:** Sun Feb 07, 2010 3:30 am

Hello Mike,

XTra nice Class !!!
Very useful and reusable !
Thanks

taobert · **Posted:** Sun Feb 07, 2010 1:10 pm

Thanks Mike

But I've a little question about 'OGLTestBench.fbs' :
Why the background (behind the triangle) is continually flashing with strange things ... on my PC (Win XP/SP3).

Gerome · **Posted:** Sun Feb 07, 2010 1:22 pm

taobert wrote:

Thanks Mike

But I've a little question about 'OGLTestBench.fbs' :
Why the background (behind the triangle) is continually flashing with strange things ... on my PC (Win XP/SP3).

Taobert,

And about :
- your CPU ? 64 or 32 bits ?
- your video card ? RAM ?
- your screen resolution ? 32k, 24k, 16k or 256 colors ?

taobert · **Posted:** Sun Feb 07, 2010 2:36 pm

Gerome wrote:

And about :
- your CPU ? 64 or 32 bits ?
- your video card ? RAM ?
- your screen resolution ? 32k, 24k, 16k or 256 colors ?

Sorry, I've forgotten :oops:

- MS Windows XP Home 32-bit SP3
- CPU Intel Celeron 331 2.66GHz
- RAM 1.3GB Dane-Elec Single-Channel DDR @ 133MHz 2.5-3-3-6
- Intel 82865G Graphics Controller, memory 96MB
- Screen : 1280x768, 32 bits per pixel, 60MHz

Codeman · **Posted:** Sun Feb 07, 2010 2:36 pm

just try this one :
i think it could be just a needed call to the glclear function

Code:

'==================================================================
' Simple demo of COGLTestApp usage
'==================================================================

#Uses "@|WIN32"
#Option Strict

' All OpenGL defines are also loaded via this include file.
#Include "COGLTestApp.inc"

' This creates an invisible OpenGL-ready window.
Dim TestApp As New COGLTestApp("OpenGL Test Bench", AddressOf Render)

' This positions and shows it on the screen. Other global declaration and
' initialization code should also go in here -- BEFORE the TestApp window's
' main loop is set off by TestApp.Run().
Center(TestApp.hWnd())
Show(TestApp.hWnd())
glclearColor(!0,!0,!0,!1.0)
' This triggers TestApp's main loop. NO CODE FOLLOWING THIS COMMAND will be
' executed UNTIL AFTER TestApp's window is destroyed by clicking its X button.
TestApp.Run()
'==================================================================
' Any app termination code may follow, but this app ends here... :)
'==================================================================

' This is the main rendering subproc whose entry point is passed to the
' TestApp object at its creation time. The actual name is irrelevant
' since it's referenced in the class code only by its entry point.
Sub Render()
glClear(GL_COLOR_BUFFER_BIT BOr GL_DEPTH_BUFFER_BIT)
   glBegin(GL_TRIANGLES)
      glColor3d(1.0, 0.0, 0.0)
      glVertex2i(0, 1)
      glColor3d(0.0, 1.0, 0.0)
      glVertex2i(-1, -1)
      glColor3d(0.0, 0.0, 1.0)
      glVertex2i(1, -1)
   glEnd()
End Sub

taobert · **Posted:** Sun Feb 07, 2010 2:40 pm

Yes, it works !
A plain black background ...
Thanks Codeman

Mike Lobanovsky · **Joined:** Tue Apr 19, 2005 7:22 am **Posts:** 890

taobert wrote:

Yes, it works !
A plain black background ...
Thanks Codeman

Bert, can you do me a favor?

Please don't use Codeman's suggestion (use the initial script) BUT:
- in between lines 77 and 78 of COGLTestApp.inc please insert the following line: "Wc.hbrBackground = 19"
- run the script and tell me if this paints the background in black.

Under my XP SP3, this line isn't necessary. It adds a black background brush to the newly created window but, since background erasure is suppressed by

Code:

Case WM_ERASEBKGND
    Return 1

my assumption was that I won't need any background brush for this window at all.

So please check if this helps (without Codeman's amendment), will you?

Thanks,

Mike

taobert · **Posted:** Sun Feb 07, 2010 9:02 pm

Mike Lobanovsky wrote:

Bert, can you do me a favor?

Please don't use Codeman's suggestion (use the initial script) BUT:
- in between lines 77 and 78 of COGLTestApp.inc please insert the following line: "Wc.hbrBackground = 19"
- run the script and tell me if this paints the background in black.

Under my XP SP3, this line isn't necessary. It adds a black background brush to the newly created window but, since background erasure is suppressed by

Code:

Case WM_ERASEBKGND
    Return 1

my assumption was that I won't need any background brush for this window at all.

So please check if this helps (without Codeman's amendment), will you?

Thanks,

Mike

No, unfortunately, this does not paint the background in black. I've a "flashing" background with black stripes scrolling up behind the triangle and sometimes I can even see intermittently some sorts of icons between those jumping black stripes.

SideshowBob · **Posted:** Sun Feb 07, 2010 9:24 pm

I'm seeing the same thing as Taobert. Codeman's amendment works but Mike's doesn't.

Mike Lobanovsky · **Joined:** Tue Apr 19, 2005 7:22 am **Posts:** 890

Thanks guys,

This means that I can safely omit assigning a background brush to the OpenGL window since its operation is suppressed.

I presume Codeman is totally right (anyway he's much better at OpenGL than I am) though the background for me is exactly the same in both cases.

But that's a pre-release version of COGLTestApp anyway, isn't it?..

That's what field testing is meant for!

Thanks again!

Mike

PS: What a pity: adding glClear() reduces FPS by 20 per cent...

SideshowBob · **Posted:** Sun Feb 07, 2010 11:54 pm

If we always got it perfect on the first try, we wouldn't need a Backspace key.

Codeman · **Posted:** Mon Feb 08, 2010 1:14 pm

mike> to avoid using glclear on each frame i think you can add double buffering or maybe triple buffering to avoid clearing the backbuffer every frame, i will try to see if i can found an easy sample to explain how it work but i will stuck the fps to the vertical synchro monitor speed so it kill the fps :p

the glclear function just erase the backbuffer hdc to get a clean one to draw the new frame and is simply necessary, it could be added directly in your class render function if you add a function to specify the rgb floats components to use on init...

-=:: FBSL ::=-

OpenGL Apps Made Easy (Skeleton OGLApp Class)

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