• 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
PhillipHamlyn

Foliage on Trees - Best Approach - Transforms or Batching ?

5 posts in this topic

Hi,

 

I have a number of tree models cribbed from Sketchup8's model repository and have converted them through a Collada pre-processor. The tree models themselves are reasonably small and make extensive use of a simple set of foliage quads transformed using a local matrix to be placed all around the tree.

 

I realise that the total number of triangles to be drawn is the same in either case, but for performance, which would be the best approach to rendering my mesh ?

 

  1. Render each foliage quad using the model transform matrix for that "leaf", giving a large number of calls but a small vertex buffer.
  2. Pre-calculate the model position of each "leaf" using the model transform, and put the baked in vertex positions into a vertex buffer, and accept a small number of calls but a large vertex buffer.

Since the accepted wisdom is to batch; I would have though option 2 would be the best performance, but want to know if I'm missing a technique here.

 

Thanks

 

Phillip

Edited by PhillipHamlyn
0

Share this post


Link to post
Share on other sites

Option 2, merge everything into one model since triangles cost almost nothing compared to draw calls when most engines have their bottleneck on the CPU to GPU communication over the motherboard. You should try reducing the detail level since 6 quads facing the camera usually look better than 10000 quads in random directions.

Edited by Dawoodoz
0

Share this post


Link to post
Share on other sites

It really depends on how many leaves/trees you're going to draw.

 

If you want to draw a large amount of trees, you're going to end up with enormous vertex buffersThe demands on video memory will grow rapidly with every baked tree you add, so unless you have a way of quickly streaming large chunks of mesh data in and out of video memory, your foliage will end up eating memory.

 

3. Hardware instancing.

 

Instanced leaves can be placed in smaller 16 bit vertex buffers accompanied by a texture (buffer) filled with transformation matrices. Combined they take up less memory, and can still be drawn in a single batch.

 

The drawback with static instance buffers is they make depth sorting harder and since all leaves carry the same vertex data, it's hard to bake local information like ambient occlusion.

Edited by eppo
0

Share this post


Link to post
Share on other sites

It really depends on how many leaves/trees you're going to draw.

 

If you want to draw a large amount of trees, you're going to end up with enormous vertex buffersThe demands on video memory will grow rapidly with every baked tree you add, so unless you have a way of quickly streaming large chunks of mesh data in and out of video memory, your foliage will end up eating memory.

 

3. Hardware instancing.

 

Instanced leaves can be placed in smaller 16 bit vertex buffers accompanied by a texture (buffer) filled with transformation matrices. Combined they take up less memory, and can still be drawn in a single batch.

 

The drawback with static instance buffers is they make depth sorting harder and since all leaves carry the same vertex data, it's hard to bake local information like ambient occlusion.

 

Eppo,

 

Thanks for the response.

 

I draw each tree individually, but my concern was that some of the trees are >20k triangles of which there are only a small number of unique vertexes (say around 500) so the best way of arranging my mesh for speed of rendering is what I'm after. It seems both you and Dawoodoz recommend not calling the shader with a new transform matrix for each "leaf", so I'm happy I'm on the right track. I haven't looked into hardware instancing at all on my project; I noticed a few comments on GameDev about it being a somewhat old approach now, and GPU speed has outstripped the need for it. Can you give me reference to a url which demonstrates or discusses using texture buffers to pass transformation matrixes - I've not come across that example of hardware instancing before ?

 

Phillip

0

Share this post


Link to post
Share on other sites

I overlooked the fact that you're using xna, which means 9.3-style stream based instancing is your only option. This is an older method, but results are the same when it comes to basic instancing.

 

This page explains it well.

 

The technique is still relevant, as it is still desired to limit the number of draw calls, limit the amount of memory used and limit the amount of dynamic data uploaded per frame.

Edited by eppo
0

Share this post


Link to post
Share on other sites

I overlooked the fact that you're using xna, which means 9.3-style stream based instancing is your only option. This is an older method, but results are the same.

 

This page explains it well.

 

The technique is still relevant, as it is still desired to limit the number of draw calls, limit the amount of memory used and limit the amount of dynamic data uploaded per frame.

 

Now that; ... that is cool.

 

I hadn't realised that hardware instancing multiplies the number of calls to the shader by the number of instances in the instance buffer - I had mistakenly assumed that it was a method of merging two vertex buffers together (i.e. using two streams of data to create one combined vertex buffer). Don't know where I got that idea from. I will definitely pursue this.

 

Phillip

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