Question

Can you draw an image directly onto a Renderbuffer Object?

Asked by: vedeveloper

Using OpenGL and I'm trying to draw an image off screen. I originally tried hiding the window but this only resulted in the saved image being a screen grab of whatever was being shown at the windows coordinates.

I'm wondering if I can use a Renderbuffer Object to solve the problem. I'm not sure if this is only used to render already existing images or if it can be drawn onto directly ( i.e. glBegin()......glEnd() ).

Any other suggestions of how I might be able to draw and image off screen and save it would be welcome as I'm quickly running out of ideas.

P.S. I know that there are Graphics Engines out there that allow you to do this with a simple function call but I'm not looking to go down that route at the moment.

Thanks.

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2009-08-14 at 01:59:13ID24652309
Tags

C++

,

OpenGL

,

Visual Studio

,

Graphics

,

Off Screen Rendering

,

Buffers

Topics

OpenGL Graphics & Game Programming

,

Microsoft Visual C++.Net

Participating Experts
1
Points
400
Comments
9

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. Drawing circles in OpenGL
    I need to draw circles using OpenGL with Windows NT. The drawing routing should be very fast. The frame-code is: glViewport(0, 0, w, h); glLoadIdentity(); glOrtho(xmin, xmax, ymin, ymax, 1.0f, -1.0f); glInitNames(); glPushName(1); ...
  2. mixing direct draw with opengl
    I want to draw bitmaps over my opengl generated graphics, and have tried using raster graphics, only to find the frame dropped considerably ( most 3d cards are optimised for 3d operations and not raster graphics ). I then tried to draw the bitmaps as texture mapped quads, b...
  3. opengl render context
    In windows GDI, when you want to draw to the screen you create a device context and use the HDC (handle to the device context) with any function, for example: BOOL Ellipse(HDC hdc, int nLeftRect, ...); now... in opengl programing you don't specify the HRC (handle to render c...
  4. How do I make the last object drawn in a 2D openGL wind…
    I have a 2D openGL window. I draw several object which overlap one another. I need the very last object that I draw to be displayed as the "TOP" object. Currently, the last object I draw is getting hidden behind the earlier drawn objects. Any thoughts? Thank you.
  5. Best Method to draw XYZ Coordinates
    Looking for the best method to draw lines and arcs from XYZ coordinates read from a text file using C#. I am not sure which one of these will be best, .Net framework drawing classes or OpenGL or DirectX or GDI+ An example or link to in the best (easiest) technology would gr...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: ikeworkPosted on 2009-08-15 at 01:21:13ID: 25104553

Hi vedeveloper,

Here is an example using the EXT_framebuffer_object extension.

http://www.codesampler.com/oglsrc/oglsrc_14.htm#ogl_frame_buffer_object

It renders off-scrren into a texture and renders that texture mapped onto a cube on-screen then.

ike

 

by: ikeworkPosted on 2009-08-15 at 01:32:21ID: 25104570

 

by: ikeworkPosted on 2009-08-15 at 01:37:14ID: 25104582

>> I'm not sure if this is only used to render already existing images or if it can be drawn onto directly ( i.e. glBegin()......glEnd() ).

You can render to it, like you render to the normal screen-Frambuffer with all gl-commands, including glBegin, glVertex3f, glEnd etc..

 

by: vedeveloperPosted on 2009-08-17 at 01:06:03ID: 25112278

I've already come across these links you posted, the problem I had was that as you said, the example code only renders a texture and not a drawing.  I'll have another look to see if they're making more sense now.

Thanks.

 

by: ikeworkPosted on 2009-08-17 at 02:38:38ID: 25112676

>> renders a texture and not a drawing

Not sure what you mean by "drawing". However, you can render to the texture first and then either map it to a 3d Quad or copy it directly into the Frambuffer with glDrawPixels or write it to a file.

 

by: vedeveloperPosted on 2009-08-17 at 02:45:29ID: 25112712

What I'm looking to be able to do is draw somethingoff screen, I'm thinking the Renderbuffer, then save it as an image without ever having to display on screen.

I've tried just drawing directly to GL_BACK but this doesn't work for Windows Vista as if the image is not rendered onto the screen the saved image will just be black. I've looked around the web for examples of drawing off screen with OpenGL but most forum relating to this usually point the person in the direction of a Graphics Engine like Qt.

My main objective here is to be able to render OpenGL images off screen and save them. I'm suspecting that drawing to the Renderbuffer might be a way of going about this.

 

by: vedeveloperPosted on 2009-08-21 at 02:22:44ID: 25150120

I managed to get this fixed using glReadPixel and reading the buffer.

 

by: ikeworkPosted on 2009-08-21 at 04:26:57ID: 25150657

Happy you fixed it :) From which buffer did you read it? From the normal framebuffer? I'm wondering, because your question was rendering off-screen, which was answered.

 

by: vedeveloperPosted on 2009-08-21 at 04:30:13ID: 31615714

I read it from the BackBuffer which I render the image to. Thanks for responding to the question.

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...