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annoyer101

OpenGL Blitting in OpenGL

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annoyer101    100
Hello. A Few Weeks Ago I Finally Finished A Text-Based Game. I Like The Plot To The Game, But, Being A Far-From-Original-Text-Based Game, It Is Pretty Boring. So, I Decided To Do Something I Never Thought I Could Possibly Do In My Whole Life... Learn OpenGL (Which Actually Is Proving To Be Not Nearly As Bad As I Thought). Since I've Made More Progress In This Library Then Ones I Have Tried Before, I've Finally Decided That I Will Use C and OpenGL. So What I Would Like To Do With My Game Is Have A Picture For Every Time Someone Presses A Key. The Picture Will Be A Single 2d Picture And Will Instantly Switch To Another Picture When The Player Presses A Key. Then It Will Sort Of Be Like A Text Based Game, But With Images I Make In MSPaint! There Is Only One Problem With This: [help] I Have Know Idea How To Blit Images In OpenGL! [help] How Is This Done? I Always Have Problems When I Try To Blit An Image In Graphics Libraries! So I Really, Really Need Help! I'm Not Having A Problem With Opengl Blitting (Yet...), I Just Haven't Have The First Clue On How To. So Help Is Very Greatly Appreciated. Thank You So, So Much To Anyone Who Helps Me. Sincerely, Annoyer

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Guest Anonymous Poster   
Guest Anonymous Poster
Your best bet would be to load the image as an OpenGL texture and create a new quad to render to the screen. Then use the texture on the quad.

Blitting directly to the screen in OpenGL is generally not recommended. I've wanted to do the same thing in the past, but a lot of people claim that blitting directly to the buffer causes the application to run slower for some reason.

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Guest Anonymous Poster   
Guest Anonymous Poster
First, you need to use glRasterPos to set the position on the screne. Then you use the command glDrawPixels and pass a pointer that points to the pixels data in the memory to the function. You can find a lot of the functions and descriptions for what they do here:

http://windowssdk.msdn.microsoft.com/en-us/library/ms537062.aspx

You can even go a bit farther and zoom and possibly rotate the image as well.

I'd highly recommend getting the OpenGL reference book, or downloading the PDF from opengl.org.

Also, I think it would be a good idea to use SDL because then you can use it to control the window that OpenGL renders to and also load your images into video memory and still pass it to glDrawPixels.

Hope this helps :)

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Odiee    100
OMG :lol: I never think I never in my life have seen someone using capital letters in every single word, and no mistakes, geez. :)

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AndyEsser    394
I mean, I must admit that I use capitals at the beginning of all my user messages in software I write. But it's kinda 'annoy'ing to read on a forum post.

Hope you've got everything sorted though? I'm also quite interested in bitmap blitting so this post was helpful to me. :P

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