# OpenGL OBJ to indexed VBO

## Recommended Posts

I'm having problems wrapping my head around on how to convert a OBJ file to a indexed interleaved VBO as OBJ uses separate indexes for vertex, normal, texcoords instead of just 1 for all as OpenGL. Now i only use the vertices and it loads and works great, but i need help on how to get vertex, normal and texcoords (using a single index).

##### Share on other sites
(Or of course, you could search for some Obj tool or source).
Anyway ... given a simple model that consists of a Vertex, tex coords and normals and a face index set you need to parse this into a vertex_array_friendly format.

The trick is to understand that the Obj file format is an optimized for storage format and not optimized for rendering. So - with that in mind you should essentially:

read the list of vertex coords and store in a temp vertex list
Do the same for the texture and normals
Then read each face in turn (and each face will have a set of indexes into the vertex, texture and normal temp lists). Use these indexes to obtain the corresponding vertex from the temp vertex list, the face-texture index to read the texture-coord from the temp texture list and so on for all the attributes. Finally, store the result into the Final_array_list and record the index in the final_index_list

see this

## Create an account

Register a new account

• ## Partner Spotlight

• ### Forum Statistics

• Total Topics
627664
• Total Posts
2978522
• ### Similar Content

• 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:

• By Defend
I've had a Google around for this but haven't yet found some solid advice. There is a lot of "it depends", but I'm not sure on what.
My question is what's a good rule of thumb to follow when it comes to creating/using VBOs & VAOs? As in, when should I use multiple or when should I not? My understanding so far is that if I need a new VBO, then I need a new VAO. So when it comes to rendering multiple objects I can either:
* make lots of VAO/VBO pairs and flip through them to render different objects, or
* make one big VBO and jump around its memory to render different objects.
I also understand that if I need to render objects with different vertex attributes, then a new VAO is necessary in this case.
If that "it depends" really is quite variable, what's best for a beginner with OpenGL, assuming that better approaches can be learnt later with better understanding?

• 10
• 10
• 12
• 22
• 13