WebAcademy.info

<h2 style="text-align: center;">
<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgggSgTSoJI_9muqSCAORiJtBMRjvl-VOCZmBFp1Igep2ahdJKdixtSxpEEc-7jxG98dXSFKpE9cEsHSZ-2KapJcMpn7yYbVGnf5IN8AUtj6W7AkFaoieM1Stl3c4SFCjgjJM1thm3tWTel/s1600/Untitled.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="192" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgggSgTSoJI_9muqSCAORiJtBMRjvl-VOCZmBFp1Igep2ahdJKdixtSxpEEc-7jxG98dXSFKpE9cEsHSZ-2KapJcMpn7yYbVGnf5IN8AUtj6W7AkFaoieM1Stl3c4SFCjgjJM1thm3tWTel/s1600/Untitled.png" width="400" /></a></h2>
<div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">In this lesson, you will learn what OpenGL is and how it enables you to program in 3D.</span></div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">What exactly is OpenGL? It's a way to draw stuff in 3D. It can also be used for 2D drawing, but this site doesn't focus on that. There are better tools for straight 2D drawing, such as SDL and Allegro.</span></div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">The graphics card is where the 3D computation happens. The purpose of OpenGL is to communicate with the graphics card about your 3D scene.</span></div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">So why not talk to the graphics card directly? Each graphics card is a little different. In a sense, they all speak different "languages". To talk to them all, you can either learn all of their languages, or find a "translator" that knows all of their languages and talk to the translator, so that you only have to know one language. OpenGL serves as a "translator" for graphics cards.</span></div>
</div>
<div style="text-align: justify;">
<span style="font-family: Helvetica Neue, Arial, Helvetica, sans-serif;"><br /></span></div>
<h3 style="text-align: center;">
<span style="font-family: inherit;">
Getting OpenGL Set Up</span></h3>
<h3>
<span style="font-family: inherit;">Set Up on Windows:</span></h3>
<div>
<div style="text-align: justify;">
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">This lesson will explain how to get OpenGL and GLUT set up on Windows. We'll use the Visual C++ Express 2005 IDE to edit, compile, and run our programs. Visual C++ Express is a free IDE. To use it, you will have to register, which is free, within 30 days. You can use another IDE if you prefer, but getting it set up will be a little different.</span><br />
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;"><br /></span></div>
<h3 style="text-align: justify;">
<span style="font-family: inherit;">
Downloading and Installing</span></h3>
<div style="text-align: justify;">
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">First, download and install the necessary software using the following instructions:</span></div>
<ol>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Download <a href="http://msdn.microsoft.com/vstudio/express/">Visual C++ Express</a> and the <a href="http://www.microsoft.com/downloads/details.aspx?familyid=0baf2b35-c656-4969-ace8-e4c0c0716adb&displaylang=en">Microsoft Platform SDK</a> from the Microsoft website. Note that when you download the SDK, it may say something about Windows Server. Don't worry about that; it'll install just fine on any modern version of Windows.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Install Visual C++ and the SDK.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Download the OpenGL installer from <a href="http://www.videotutorialsrock.com/opengl2.exe">here</a> and the GLUT binary from <a href="http://www.xmission.com/~nate/glut.html">here</a>.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Run the OpenGL installer.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Extract GLUT to the directory of your choice. You can do this by creating a new directory, locating and opening the ZIP file using Windows Explorer, and copying the files to the new directory using copy-paste. Alternatively, you can use a free program like <a href="http://www.winzip.com/">WinZip</a> to extract GLUT.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">In the directory to which you extracted GLUT, make two folders, one called "include" and one called "lib". In the "include" folder, create another folder called "GL", and move glut.h to that folder. Move all of the other files that you extracted for GLUT into the "lib" folder.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Run Visual C++ Express. Go to Tools -> Options, then Projects and Solutions -> VC++ Directories. Note where it says "Show directories for". You'll want to change the directories for include files by adding "<i>x</i>\include", "<i>y</i>\include", and "<i>z</i>\Include" and to change the directories for library files by adding "<i>x</i>\lib", "<i>y</i>\lib", and "<i>z</i>\Lib", where "<i>x</i>" is the folder where you installed OpenGL, "<i>y</i>" is the folder where you extracted GLUT, and "<i>z</i>" is the folder where you installed the Microsoft Platform SDK.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Change your PATH environment variable as follows: go to the control panel, and go to System. Go to the "Advanced" tab and click on "Environment Variables". Find the "PATH" (or "Path") variable. Change it by adding ";<i>x</i>\lib;<i>y</i>\lib;<i>z</i>\Lib" (without the quotes) to the end of it, where again, "<i>x</i>", "<i>y</i>", and "<i>z</i>" are the folders where you installed OpenGL, GLUT, and the Microsoft Platform SDK. Make sure there are no spaces before or after the semicolons.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Reboot your computer, so that Windows will recognise the changes to the PATH environment variable.</span></li>
</ol>
<center>
</center>
<h3>
<span style="font-family: inherit;">
Compiling and Running the Test Program</span></h3>
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">To make sure that everything was set up correctly, we're going to see if we can get a test program to work.</span><br />
<ol>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Download <a href="http://www.videotutorialsrock.com/opengl_tutorial/cube/cube.zip">this test program</a> and extract it somewhere on your computer.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Run Visual Studio C++. Go to File -> New -> Project From Existing Code.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Click next to indicate that you are making a Visual C++ project.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Set the project file location to the folder to which you extracted the test program. Enter in a name for your project (such as "cube") and click next.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Change the project type from "Windows application project" to "Console application project", and click next.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Click next, then click finish to finish creating the project.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Go to Project -> Properties. Click on Configuration Properties. Click the "Configuration Manager" button in the upper-right corner. Change the "Active solution configuration" from "Debug" to "Release". Click close, then click OK.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">In Project -> Properties, go to Configuration Properties -> General. Where it shows the output directory as "Release", backspace the word "Release", and click OK. This makes Visual C++ put the executable in the same directory as the source code, so when our program needs to open a file, it looks for it in that directory. In this case, the program will have to load in an image file called "vtr.bmp".</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Go to Build -> Build project_name to build your project.</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">There should be two warnings about ignoring /INCREMENTAL. You don't have to, but if you want, you can fix them as follows. In Project -> Properties, go to Configuration Properties -> Linker, and change "Enable Incremental Linking" from "Yes (/Incremental)" to "No (/Incremental:No)".</span></li>
<li style="text-align: justify;"><span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Run the program by going to Debug -> Start Without Debugging. If all goes well, the test program should run.</span></li>
</ol>
<div style="text-align: justify;">
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Note that you'll have to set up a project every time you want to work on a program from my site, so you'll have to repeat steps 1 - 11 above.</span></div>
<div style="text-align: justify;">
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">I'd like to point out a couple of things about the program. First of all, notice that the project has a file called "Makefile". It's not used on Windows; it's only needed for Linux, Mac OS X, and other UNIX-based operating systems. But Visual C++ will automatically ignore the file, so you don't have to worry about removing it from the project.</span></div>
<div style="text-align: justify;">
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Secondly, take a look at main.cpp. Notice that the include directives for OpenGL appear after the <kbd style="font-weight: bold;">#include</kbd> directives for the normal C++ include files. If we had them in the opposite order, because of the Windows download that I recommended for GLUT, you'd get a compiler error. So make sure that the include files for the standard C++ stuff appear before the include files for OpenGL.</span></div>
<div style="text-align: justify;">
<span style="background-color: white; font-family: Helvetica Neue, Arial, Helvetica, sans-serif;">Whew! We've finished setting up OpenGL. Now we're ready to learn how to program in 3D.</span></div>
</div>

What is OpenGL?

In this lesson, you will learn what OpenGL is and how it enables you to program in 3D. What exactly is OpenGL? It's a way to draw stuff in 3D. It can also be used for 2D drawing, but this site doesn'…

WebAcademy.info

What is OpenGL?

The basics of OpenGL

តាមយើង

មតិ

ការផ្សាយប្រចាំខែ