• 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

Rendering multiple complex animated models

1 post in this topic

By now I think we've all seen the tank example, its a hierarchically composed model. Each part of the model has an associated effect, embedded into the asset and its own vertex and index buffer.

The provided examples always take one object to render (the tank) which has more or less the same texture and effect all over. They navigate the model as a tree rendering each part in sequence applying transformations until the tank is fully composed on screen, it works and looks nice and the code is fairly neat.

However, this looks awfully like a "laboratory conditions" kind of success that would not hold a decent FPS rate in real gameplay.
Suppose we have many objects to render, each of which has various parts, some objects are instances of the same model, some use different models, some models have parts that share the same properties as those of a part of another model, like two different models that both have rubber wheels. Most models have two or three, if not more, different effects on their different parts, like wheels, hull and cockpit glass.
The rendering cycle proposed by the tank example looks like it would be changing shaders and textures constantly in that scenario and does not apply any kind of batching.

Is the tank example good for a reason I may not be seeing or would a much better approach be grouping individual sub models by shader + texture (Materials) and rendering those in batches thus reducing render state changes?

[source lang="csharp"] public void Draw(Matrix viewMatrix, Matrix projectionMatrix)
// Apply matrices to the relevant bones, as discussed in the Simple
// Animation Sample.
leftBackWheelBone.Transform = wheelRollMatrix * leftBackWheelTransform;
rightBackWheelBone.Transform = wheelRollMatrix * rightBackWheelTransform;
leftFrontWheelBone.Transform = wheelRollMatrix * leftFrontWheelTransform;
rightFrontWheelBone.Transform = wheelRollMatrix * rightFrontWheelTransform;

// now that we've updated the wheels' transforms, we can create an array
// of absolute transforms for all of the bones, and then use it to draw.
Matrix[] boneTransforms = new Matrix[model.Bones.Count];

// calculate the tank's world matrix, which will be a combination of our
// orientation and a translation matrix that will put us at at the correct
// position.
Matrix worldMatrix = orientation * Matrix.CreateTranslation(Position);

foreach (ModelMesh mesh in model.Meshes)
foreach (BasicEffect effect in mesh.Effects)
effect.World = boneTransforms[mesh.ParentBone.Index] * worldMatrix;
effect.View = viewMatrix;
effect.Projection = projectionMatrix;

effect.PreferPerPixelLighting = true;

// Set the fog to match the black background color
effect.FogEnabled = true;
effect.FogColor = Vector3.Zero;
effect.FogStart = 1000;
effect.FogEnd = 3200;

Share this post

Link to post
Share on other sites
In my experience, XNA works far better with few large batches than with a bunch of small ones. It is also best to have effect and state changes kept to as few as possible. So if you have 10 models each with 5 sub-models, then you should instance each sub-model of the same type together so you have 5 batches of 10 instead of 10 batches of 5. Group all wheels together and all doors together instead of simply grouping each car's sub-models together. If a batch of sub-models requires an effect or state change, then change between batches. Each sub-model's world should be calculated by multiplying its world relative to its parent times its parent's world.

EDIT: Also, this allows you to only need one model in memory. When you send a batch of sub-models, you just simply send that one sub-model with an array of transforms. Take a look at the instancing sample by Microsoft. This method should allow you to have upwards of 100 complex models or possibly tens of thousands of simple models rendering at once. (Minecraft uses instancing.) Edited by Drakken255

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