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Drawing pixels on the screen with C

by Gza
Tags: drawing, pixels, screen
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May14-05, 04:49 AM
Gza's Avatar
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Okay, from the title of this post, you can already tell i'm pretty much a noob when it comes to C. But the situation is that I have visual c++ 6.0, and haven't been able to find any libraries with a putpixel(x,y) type function that i can use to simply plot a point within a dos window. Would i have to use some assembly to do this and mess with video memory directly? thanks for the feedback.
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May14-05, 11:12 AM
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What compiler are you using? It used to be that most computer monitors did not support graphics so graphics methods were not routinely included in compilers.

More modern compilers support "windows" type graphics. In particular, Borland's "C++ Builder" has the "Canvas" class that includes the method "Canvas->Pixels[i][j] that sets pixels at screen coords (i,j). MicrosSoft's, "Visual C++" uses "OpenGL" that includes the command "glDrawPixels(i,j)".
May14-05, 01:45 PM
P: 309
Do you want to draw in windows mode? There are several ways to accomplish this. If you you like C's procedural feel you can use the Win32 API directly without the MFC C++ OO-encapsulation classes. The basic way to acomplish this is to:.

1. Create a window, using the CreateWindow(...) function retaining the "handle" (pointer) that window
2. There is a window message handling procedure called "WndProc", which is called everytime the window receives a message (like being told to destroy itself). You need to get the "graphics" handle for the Window. This can be done in few ways, but the wizard included in the version of VC++ that I have uses a simple procedure called "BeginPaint". Looks like they learned their lesson from Java!
3. Use the "SetPixeL" function on the graphics handle of the window .

Visual C++ includes a "wizard" called "Win32 Application" which gives you a good chunk of the code that you need to accomplish this. It gives you a handle to the window it creats called "hWnd". You would then probably put your drawing functions in the WM_PAINT case of the "WndProc" procedure which handles window messages. It even gives you the handle to device context "hdc". You would then use the SetPixel function to accomplish your drawing.

May14-05, 02:34 PM
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robphy's Avatar
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Drawing pixels on the screen with C

Possibly useful examples:
May14-05, 02:38 PM
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chroot's Avatar
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C has no built-in graphical toolkit whatsoever, so you cannot, by definition, do what you're doing in C alone. You will need a library to accomplish drawing to the screen. I strongly recommend the Qt toolkit -- it's free for non-commercial use, easy as pie to use, and very, very powerful. You will not find a toolkit that's better designed or more easy-to-use.

If you need any help getting started with Qt or any other graphical toolkit, please ask for help -- I, as well as many others here, can help you.

- Warren
May15-05, 08:33 PM
Gza's Avatar
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thanks chroot and everyone else for your valuable advice and resources. i'm now able to draw on a window. I'll come back here to ask more questions when i begin work on my fully immersive 3d-engine for a massively multiplayer online game, with motion dictated by true to life physics, involving fields from general relativity to quantum mechanics.
May15-05, 08:37 PM
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Hurkyl's Avatar
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Oh, I thought everyone had one of those lying about someplace.
May15-05, 09:21 PM
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go with SDL its very easy to learn...but if your looking for the simplest library....
its graphics.h(and prolly one fo the oldest) was usually packaged with C(borland) but VC++6.0 took it out. I can send you the old version.

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