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Lab 1: OpenGL Tutorial

Lab 1: OpenGL Tutorial. CS 282. What’s the plan for today?. Go over our framework code. Learn some basic OpenGL! Reveal Lab 1 Answer questions. Framework Environment. C/C++ and OpenGL Code will be given with Makefiles You can compile in Linux, Mac, and Windows!

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Lab 1: OpenGL Tutorial

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  1. Lab 1: OpenGL Tutorial CS 282

  2. What’s the plan for today? • Go over our framework code. • Learn some basic OpenGL! • Reveal Lab 1 • Answer questions

  3. Framework Environment • C/C++ and OpenGL • Code will be given with Makefiles • You can compile in Linux, Mac, and Windows! • You must use the framework

  4. What should you know? • At the very least • You’ve programmed before • You know the programming cycle • Better for you if • You are familiar with C/C++ • Amazing if • You already know OpenGL • Have a degree in Computer Science

  5. Framework • Where do I get it?! • Resources in Class Website • This lab’s framework provides you with • An initial OpenGL window • Callback functions you will need

  6. What is OpenGL? • A powerful, open source graphics library • Widely used in both industry and academia • Capable of rendering 3D geometries with a plethora of effects • Keeps a “global” state • Transformation, projection matrices • Attributes from primitives

  7. Exercise: Compiling • Compile the framework • Change window size, position, and title

  8. Exercise: Drawing Things! • Since you guys are now pros, let’s draw things! • Every GL primitive starts with glBegin(…), and ends with glEnd () • Example: glBegin (GL_POINT); glVertex3f( 1.0,1.0,1.0); glEnd()

  9. Exercise: Drawing Quads • Find the DrawGLScene() function • After glLoadIdentity(), create a GL primitiveusing GL_QUADS

  10. Exercise: Drawing Quads • Add this code • And this code…

  11. What just happened?! • OK, that’s weird, why is the screen yellow? • We’ve basically rendered our object too close for us to really see it. So, we need to move (or translate) it further back.

  12. Translation and Rotation • Rotation (unsurprisingly) rotates the primitive,BUT rotates it around the “world” axis, NOT itslocal axis • Hint: You can think of the camera as always being at the world origin(0,0,0) • Translation “moves” the primitive around to adifferent location • The order you do translations and rotations in MATTERS

  13. Translation and Rotation • Rotate • Translate

  14. Translation and Rotation • Rotate then Translate • Translate then Rotate

  15. Translation and Rotation • WARNING!!! • OpenGL will perform translations and rotations IN THE OPPOSITE ORDER YOU WRITE THEM IN CODE • i.e. writing the following in code: …glTranslate(...)glRotate(…) …Will rotate then translate the primitive

  16. Translation and Rotation • Important things to keep in mind: • Translate/Rotate operates relative to the world origin • The order of translations and rotations matters • OpenGL will perform translations and rotations in the OPPOSITE order you list them in code

  17. Exercise: Finish the cube • Add this line of code above your primitive in your drawing function. • Finish the rest of the cube. • Change the color of each side to something else! glColor3f( red, green, blue );

  18. Callbacks • GLUT allows us to interface between events (such as clicking, keyboard input, etc.) and OpenGL.

  19. Lab 1 • Implement a camera to move around in OpenGL. • Use the callback functions provided for you. • Use the cube as a way to debug your camera. • Make sure you at least create a vector, camera, and framework class.

  20. Questions?

  21. Useful sites • OpenGL Reference Pages: http://www.opengl.org/sdk/docs/man/ (what we use)http://www.opengl.org/sdk/docs/man4/ (latest ver.) • NeHe Tutorials (under Legacy Tutorials):http://nehe.gamedev.net/ • Note: As of Aug. 2011, the current tutorials are a little out-of-date/deprecated, but in the process of being updated. They still give a good explanation of the basics, but don’t expect to be able to run the code.

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