• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
wh1sp3rik

Indexed vs Non-indexed primitives

11 posts in this topic

Hello,

 

I am trying to choose the right way for me. I am rewriting some parts of my engine and now i stand before this question.

I will use these indexed/nonindexed primitives only for imported models ( characters or objects ), not for terrains, particles.

 

Let's say the advantages and disadvantages.

 

Advantages of indexed primitives:

  • Primitive can take less memory
  • They are rendered faster ( because of first point ? )

Disadvantages of indexed primitives:

  • More complex models needs normals/bitangents/tangents/uvs/colours per vertex
  • We have to bind two buffers, vertex and index
  • cache miss, if indexes not ordered propertly

and nonindexed are opposite of these.

 

Is indexed primitives really faster to render for medium complex objects ( even, 50% of vertices needs different normals/tangents/.... so they are reperating actually ). Perhaps it's easy to answer, i would like to hear opinions from more experienced users.

 

Thank you very much.

 

 

0

Share this post


Link to post
Share on other sites

The other advantage of indexed primitives that often seems ignored - probably because it's not as directly measurable as e.g. memory usage - is that they let you join multiple primitive types together.  Say you have a model that may be composed of multiple strips, or a mixture of strips and fans - using indexed primitives allows you to take the entire model in one draw call, whereas with non-indexed you would have multiple calls.  That can be a big win and can be a fair tradeoff of memory usage versus batching potential.

 

(Sure, you could do the same with primitive restart, but indexing gives you it on GL_VERSIONs that don't have primitive restart available, and also allows for mixing of different primitive types, which primitive restart doesn't.)

0

Share this post


Link to post
Share on other sites

[quote name='wh1sp3rik' timestamp='1358426328' post='5022498']
I am trying to choose the right way for me.
[/quote]

 

it depends on what you need, obviously. I needed speed (the 10,000 blades of grass challenge). testing revealed indexed to be the way to go.

 

determine your selection criteria (speed, memory, etc). write some test routines. the numbers don't lie.

1

Share this post


Link to post
Share on other sites

In the general case for artist-authored meshes you'd use in a game, indexing is going to be a win. It will allow you to share verts from multiple triangles which not only saves you memory, but can also save you vertex shader executions.

Edited by MJP
2

Share this post


Link to post
Share on other sites

Thank you very much for your answers.

 

I will stay with indexed primitives and i will try find a way, how to improve it :)

0

Share this post


Link to post
Share on other sites

Let's say the advantages and disadvantages.
 
Advantages of indexed primitives:

  • Primitive can take less memory


They take less memory if you have enough shared vertices; otherwise the index buffer will be larger than the amount by which you can reduce the vertex buffer(s). 



Great post!

I admit I'm pretty behind the times here. Having said that, what domains are you finding shared vertices to be limited?
0

Share this post


Link to post
Share on other sites

Let's say the advantages and disadvantages.
 
Advantages of indexed primitives:

  • Primitive can take less memory

 

They take less memory if you have enough shared vertices; otherwise the index buffer will be larger than the amount by which you can reduce the vertex buffer(s). 

 


Great post!

I admit I'm pretty behind the times here. Having said that, what domains are you finding shared vertices to be limited?

Hard corners and edges don't have shared vertices. The cube is the typical and ultimate example; it has eight corners but needs 24 vertices because all corners and edges are hard, and there are no shared vertices at all. Basically, any time you have two vertices that share position but not some other attribute such as normal.

 

Smooth corners and edges, for example a sphere (with the possible exception for special places such as its poles), can share vertices since all attributes are typically continuous over the surface. Hard corners and edges introduce discontinuities that break the shared vertices.

0

Share this post


Link to post
Share on other sites

Let's say the advantages and disadvantages.
 
Advantages of indexed primitives:

  • Primitive can take less memory

 

They take less memory if you have enough shared vertices; otherwise the index buffer will be larger than the amount by which you can reduce the vertex buffer(s). 

 


Great post!

I admit I'm pretty behind the times here. Having said that, what domains are you finding shared vertices to be limited?

Hard corners and edges don't have shared vertices. The cube is the typical and ultimate example; it has eight corners but needs 24 vertices because all corners and edges are hard, and there are no shared vertices at all. Basically, any time you have two vertices that share position but not some other attribute such as normal.

 

Smooth corners and edges, for example a sphere (with the possible exception for special places such as its poles), can share vertices since all attributes are typically continuous over the surface. Hard corners and edges introduce discontinuities that break the shared vertices.

 

But even in this case, the indexed version is smaller. Assume that you have really small vertices (16 bytes each). You're still talking about 24 vertices plus 36 (2 byte) indices for the indexed version: 456 bytes total. For the non-indexed version, you're looking at 36 verts, for a total of 576 bytes. As the vertices get larger (to a more realistic size), the numbers just get worse. In the absolute best case for non-indexed, you could render the cube as 6 separate tri-strips of four vertices each, so you only need the 24 vertices... but you still need enough other meta-data to remember that it's actually 6 strips of length 4. Plus, you're now issuing 6 draw calls for one cube.

 

Basically... it's almost always better to use indices these days. The vertex caching wins inside the GPU, the simplification in tools, the reduced memory footprint in nearly every case, ... it's pretty clear cut.

1

Share this post


Link to post
Share on other sites

This is one case where the GS stage is genuinely useful; you have access to all of the position data on a per-face basis, so you could use that to generate normals and texcoords for a cube (which tend to be pretty standard) while still keeping the vertex count down.

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0