# OpenGL Using Vertex Buffer Objects in OpenGL 2.1 and C

## Recommended Posts

(I specified 2.1 because my laptop won't go past that version. I would have probably done this anyway since 3.x and on introduces shaders as mandatory?).
Thanks to Wikipedia: [url="http://en.wikipedia.org/wiki/Vertex_Buffer_Object"]http://en.wikipedia.org/wiki/Vertex_Buffer_Object[/url] I am starting to grasp how simple it can be to use VBO's (I am still not positive about IBO's?). What I have understood so far is the primary reason to use them is a performance boost gained due to the fact that data is now stored in video memory.

What I would like to know is how I am supposed to use them in a practical context. For instance, all of what I have seen has been setting up one Vertex Buffer Object and drawing one triangle or one cube, etc. What if I want to draw 2 or more? Do I set up a new VBO for each entity that I want to draw? Or do I magically append to some static VBO that I setup early on?

##### Share on other sites
Memory usage strategy strongly depends on your setup. Do you need to draw many different objects (large VBO holding objects), or only few (no harm in one VBO per object)? Do you want to draw many objects with the same data (one location (VBO or a part of it) per shared object)? Do you have very large meshes for which you wish to cull some parts? (maybe several VBOs per object). Answers to such (and many other) questions will help you decide what strategy to use.

As for "magical" appending: no one forces you to allocate a VBO that can only hold one object: you can safely create a memory pool out of VBO, that is, a large VBO which you will fill with objects as you need them. But again, this is only useful in case when you're certain you won't waste too much memory (which would indicate you chose a wrong strategy).

And, it's not strictly "video" memory. It's just that the memory is managed by the driver. The exact location can be anywhere, but it's the driver that decides where, depending on buffer usage and some other implementation details. Furthermore, since the driver is in charge, it can freely move the data while you're not looking, but it's free to do so since client code has no way of depending on exact data location anyway (glMapBuffer is not an exception. In fact, it only emphasizes this). Edited by capricorn

##### Share on other sites
There is an app for that
http://www.opengl.org/wiki/Vertex_Buffer_Object
http://www.opengl.org/wiki/VBO_-_more

and also
http://www.opengl.org/wiki/VBO_-_just_examples

##### Share on other sites
Thank you for the help. I am slowly starting to understand VBOs and how they are to be used.

## Create an account

Register a new account

• ### Forum Statistics

• Total Topics
627700
• Total Posts
2978695
• ### Similar Content

• A friend of mine and I are making a 2D game engine as a learning experience and to hopefully build upon the experience in the long run.

-What I'm using:
C++;. Since im learning this language while in college and its one of the popular language to make games with why not.     Visual Studios; Im using a windows so yea.     SDL or GLFW; was thinking about SDL since i do some research on it where it is catching my interest but i hear SDL is a huge package compared to GLFW, so i may do GLFW to start with as learning since i may get overwhelmed with SDL.
-Questions
Knowing what we want in the engine what should our main focus be in terms of learning. File managements, with headers, functions ect. How can i properly manage files with out confusing myself and my friend when sharing code. Alternative to Visual studios: My friend has a mac and cant properly use Vis studios, is there another alternative to it?

• Both functions are available since 3.0, and I'm currently using glMapBuffer(), which works fine.
But, I was wondering if anyone has experienced advantage in using glMapBufferRange(), which allows to specify the range of the mapped buffer. Could this be only a safety measure or does it improve performance?
Note: I'm not asking about glBufferSubData()/glBufferData. Those two are irrelevant in this case.
• By xhcao
Before using void glBindImageTexture(    GLuint unit, GLuint texture, GLint level, GLboolean layered, GLint layer, GLenum access, GLenum format), does need to make sure that texture is completeness.
• By cebugdev
hi guys,
are there any books, link online or any other resources that discusses on how to build special effects such as magic, lightning, etc. in OpenGL? i mean, yeah most of them are using particles but im looking for resources specifically on how to manipulate the particles to look like an effect that can be use for games,. i did fire particle before, and I want to learn how to do the other 'magic' as well.
Like are there one book or link(cant find in google) that atleast featured how to make different particle effects in OpenGL (or DirectX)? If there is no one stop shop for it, maybe ill just look for some tips on how to make a particle engine that is flexible enough to enable me to design different effects/magic
let me know if you guys have recommendations.
• By dud3
How do we rotate the camera around x axis 360 degrees, without having the strange effect as in my video below?
Mine behaves exactly the same way spherical coordinates would, I'm using euler angles.
Tried googling, but couldn't find a proper answer, guessing I don't know what exactly to google for, googled 'rotate 360 around x axis', got no proper answers.

References:
Code: https://pastebin.com/Hcshj3FQ
The video shows the difference between blender and my rotation:

• 21
• 14
• 12
• 10
• 12