# C++ [MAYA API] MItDependencyGraph won't iterate properly

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I have a function that takes in an MObject and is supposed to iterate its children and print any nodes it comes across using MItDependencyGraph:

void QueueChildrenTransforms(MObject& node)
{
MItDependencyGraph it
(
node,
MFn::kInvalid,
MItDependencyGraph::kDownstream,
MItDependencyGraph::kNodeLevel
);

MString s = "Found: ";
for (; !it.isDone(); it.next())
{
MFnDagNode child(it.currentItem());
s += child.name();
s += " ";
}
MGlobal::displayInfo(s);
}

When it is called, it only outputs the name of the node passed in to it. (If i use kInvalid as filter, which should iterate all nodes)

It doesn't seem to make a difference changing the direction or traversal priority.

I've tried different filteres as well such as kTransform and kMesh (these are the ones I want in the end, but using these filter seem to not output even the node passed in)

I'm not sure if im using the correct type of iterator for this but this is the only one I've found that lets you define the root node of the search, which I need to do.

So what am I missing here?

End goal is to pass in a transform node, and iterate through its children in order to queue any transforms found for export.

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Solved it by doing the following:

	MItDag it(MItDag::kDepthFirst, MFn::kTransform);
it.reset(node, MItDag::kDepthFirst, MFn::kTransform);

though I am still curious as to why the original approach didn't work..

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• Overview
Welcome to the 2D UFO game guide using the Orx Portable Game Engine. My aim for this tutorial is to take you through all the steps to build a UFO game from scratch.
The aim of our game is to allow the player to control a UFO by applying physical forces to move it around. The player must collect pickups to increase their score to win.
I should openly acknowledge that this series is cheekily inspired by the 2D UFO tutorial written for Unity.
It makes an excellent comparison of the approaches between Orx and Unity. It is also a perfect way to highlight one of the major parts that makes Orx unique among other game engines, its Data Driven Configuration System.
You'll get very familiar with this system very soon. It's at the very heart of just about every game written using Orx.
If you are very new to game development, don't worry. We'll take it nice and slow and try to explain everything in very simple terms. The only knowledge you will need is some simple C++.
I'd like say a huge thank you to FullyBugged for providing the graphics for this series of articles.

What are we making?
Visit the video below to see the look and gameplay of the final game:
Getting Orx
The latest up to date version of Orx can be cloned from github and set up with:
git clone https://github.com/orx/orx.git Once cloning has completed, the setup script in the root of the files will start automatically for you. This script creates an $ORX environment variable for your system. The variable will point to the code subfolder where you cloned Orx. Why? I'll get to the in a moment, but it'll make your life easier. The setup script also creates several projects for various IDEs and operating system: Visual Studio, Codelite, Code::Blocks, and gmake. You can pick one of these projects to build the Orx library. Building the Orx Library While the Orx headers are provided, you need to compile the Orx library so that your own games can link to it. Because the setup script has already created a suitable a project for you (using premake), you can simply open one for your chosen OS/IDE and compile the Orx library yourself. There are three configurations to compile: Debug, Profile and Release. You will need to compile all three. For more details on compiling the Orx lbrary at: http://orx-project.org/wiki/en/tutorials/cloning_orx_from_github at the Orx learning wiki. The$ORX Environment Variable
I promised I would explain what this is for. Once you have compiled all three orx library files, you will find them in the code/lib/dynamic folder:
orx.dll orxd.dll orxp.dll Also, link libraries will be available in the same folder:
orx.lib orxd.lib orxp.lib When it comes time to create our own game project, we would normally be forced to copy these library files and includes into every project.
A better way is to have our projects point to the libraries and includes located at the folder that the $ORX environment variable points to (for example: C:\Dev\orx\code). This means that your projects will always know where to find the Orx library. And should you ever clone and re-compile a new version of Orx, your game projects can make immediate use of the newer version. Setting up a 2D UFO Project Now the you have the Orx libraries cloned and compiled, you will need a blank project for your game. Supported options are: Visual Studio, CodeLite, Code::Blocks, XCode or gmake, depending on your operating system. Once you have a game project, you can use it to work through the steps in this tutorial. Orx provides a very nice system for auto creating game projects for you. In the root of the Orx repo, you will find either the init.bat (for Windows) or init.sh (Mac/Linux) command. Create a project for our 2D game from the command line in the Orx folder and running: init c:\temp\ufo or init.sh ~/ufo Orx will create a project for each IDE supported by your OS at the specified location. You can copy this folder anywhere, and your project will always compile and link due to the$ORX environment variable. It knows where the libraries and includes are for Orx.
Open your project using your favourite IDE from within the ufo/build folder.
When the blank template loads, there are two main folders to note in your solution:
config src Firstly, the src folder contains a single source file, ufo.cpp. This is where we will add the c++ code for the game. The config folder contains configuration files for our game.
What is config?
Orx is a data driven 2D game engine. Many of the elements in your game, like objects, spawners, music etc, do not need to be defined in code. They can be defined (or configured) using config files.
You can make a range of complex multi-part objects with special behaviours and effects in Orx, and bring them into your game with a single line of code. You'll see this in the following chapters of this guide.
There are three ufo config files in the config folder but for this guide, only one will actually be used in our game. This is:
ufo.ini All our game configuration will be done there.
Over in the Orx library repo folder under orx/code/bin, there are two other config files:
CreationTemplate.ini SettingsTemplate.ini These are example configs and they list all the properties and values that are available to you. We will mainly concentrate on referring to the CreationTemplate.ini, which is for objects, sounds, etc. It's good idea to include these two files into your project for easy reference.
Alternatively you can view these online at https://github.com/orx/orx/blob/master/code/bin/CreationTemplate.ini and here: https://github.com/orx/orx/blob/master/code/bin/SettingsTemplate.ini

The code template
Now to take a look at the basic ufo.cpp and see what is contained there.
The first function is the Init() function.
This function will execute when the game starts up. Here you can create objects have been defined in the config, or perform other set up tasks like handlers. We'll do both of these soon.
The Run() function is executed every main clock cycle. This is a good place to continually perform a task. Though there are better alternatives for this, and we will cover those later. This is mainly used to check for the quit key.
The Exit() function is where memory is cleaned up when your game quits. Orx cleans up nicely after itself. We won't use this function as part of this guide.
The Bootstrap() function is an optional function to use. This is used to tell Orx where to find the first config file for use in our game (ufo.ini). There is another way to do this, but for now, we'll use this function to inform Orx of the config.
Then of course, the main() function. We do not need to use this function in this guide.
Now that we have everything we need to get start, you should be able to compile successfully. Run the program and an Orx logo will appear slowly rotating.

Great. So now you have everything you need to start building the UFO game.
If you experience an issue compiling, check the troubleshooting article for Orx projects    for help.

Setting up the game assets
Our game will have a background, a UFO which the player will control, and some pickups that the player can collect.
The UFO will be controlled by the player using the cursor keys.
First you'll need the assets to make the game. You can download the file  assets-for-orx-ufo-game.zip which contains:
The background file (background.png😞

The UFO and Pickup sprite images (ufo.png and pickup.png😞

And a pickup sound effect (pickup.ogg😞
pickup.ogg
Copy the .png files into your data/texture folder
Copy the .ogg file into your data/sound folder.
Now these files can be accessed by your project and included in the game.

Setting up the Playfield
We will start by setting up the background object. This is done using config.
Open the ufo.ini config file in your editor and add the following:

[BackgroundGraphic] Texture = background.png Pivot = center
The BackgroundGraphic defined here is called a Graphic Section. It has two properties defined. The first is Texture which has been set as background.png.
The Orx library knows where to find this image, due to the properties set in the Resource section:

[Resource] Texture = ../../data/texture
So any texture files that are required (just like in our BackgroundGraphic section) will be located in the ../../data/texture folder.
The second parameter is Pivot. A pivot is the handle (or sometimes “hotspot” in other frameworks). This is set to be center. The position is 0,0 by default, just like the camera. The effect is to ensure the background sits in the center of our game window.
There are other values available for Pivot. To see the list of values, open the CreationTemplate.ini file in your editor. Scroll to the GraphicTemplate section and find Pivot in the list. There you can see all the possible values that could be used.
top left is also a typical value.
We need to define an object that will make use of this graphic. This will be the actual entity that is used in the game:

[BackgroundObject] Graphic = BackgroundGraphic Position = (0, 0, 0)
The Graphic property is the section BackgroundGraphic that we defined earlier. Our object will use that graphic.
The second property is the Position. In our world, this object will be created at (0, 0, 0). In Orx, the coordinates are (x, y, z). It may seem strange that Orx, being a 2D game engine has a Z axis. Actually Orx is 2.5D. It respects the Z axis for objects, and can use this for layering above or below other objects in the game.
To make the object appear in our game, we will add a line of code in our source file to create it.
In the Init() function of ufo.cpp, remove the default line:
orxObject_CreateFromConfig("Object"); and replace it with:
orxObject_CreateFromConfig("BackgroundObject"); Compile and run.
The old spinning logo is now replaced with a nice tiled background object.

Next, the ufo object is required. This is what the player will control. This will be covered in Part 2.

• bs::framework is a newly released, free and open-source C++ game development framework. It aims to provide a modern C++14 API & codebase, focus on high-end technologies comparable to commercial engine offerings and a highly optimized core capable of running demanding projects. Additionally it aims to offer a clean, simple architecture with lightweight implementations that allow the framework to be easily enhanced with new features and therefore be ready for future growth.
Some of the currently available features include a physically based renderer based on Vulkan, DirectX and OpenGL, unified shading language, systems for animation, audio, GUI, physics, scripting, heavily multi-threaded core, full API documentation + user manuals, support for Windows, Linux and macOS and more.
The next few updates are focusing on adding support for scripting languages like C#, Python and Lua, further enhancing the rendering fidelity and adding sub-systems for particle and terrain rendering.
A complete editor based on the framework is also in development, currently available in pre-alpha stage.

View full story

• bs::framework is a newly released, free and open-source C++ game development framework. It aims to provide a modern C++14 API & codebase, focus on high-end technologies comparable to commercial engine offerings and a highly optimized core capable of running demanding projects. Additionally it aims to offer a clean, simple architecture with lightweight implementations that allow the framework to be easily enhanced with new features and therefore be ready for future growth.
Some of the currently available features include a physically based renderer based on Vulkan, DirectX and OpenGL, unified shading language, systems for animation, audio, GUI, physics, scripting, heavily multi-threaded core, full API documentation + user manuals, support for Windows, Linux and macOS and more.
The next few updates are focusing on adding support for scripting languages like C#, Python and Lua, further enhancing the rendering fidelity and adding sub-systems for particle and terrain rendering.
A complete editor based on the framework is also in development, currently available in pre-alpha stage.

• Hi again,  After some looking around I have decided to base my game directly on Direct X rather than using an existing game engine.  Because of the nature of the stuff I'm doing it just didn't seem to fit very well and I kept running into road blocks.  At this point I have a big blob of code for doing fractal world generation and some collision code,  and I'm trying to put it into some form that resembles a game engine.  Since I've never used one before It's a bit alien to me ..... so can someone direct me to a book, website, article, whatever... that covers this?  I'm mainly looking for stuff that covers C++ library design. I'm not adverse to using 3rd party tools for stuff I can used them for.
• By chiffre
Introduction:
In general my questions pertain to the differences between floating- and fixed-point data. Additionally I would like to understand when it can be advantageous to prefer fixed-point representation over floating-point representation in the context of vertex data and how the hardware deals with the different data-types. I believe I should be able to reduce the amount of data (bytes) necessary per vertex by choosing the most opportune representations for my vertex attributes. Thanks ahead of time if you, the reader, are considering the effort of reading this and helping me.
I found an old topic that shows this is possible in principal, but I am not sure I understand what the pitfalls are when using fixed-point representation and whether there are any hardware-based performance advantages/disadvantages.
(TLDR at bottom)
The Actual Post:
To my understanding HLSL/D3D11 offers not just the traditional floating point model in half-,single-, and double-precision, but also the fixed-point model in form of signed/unsigned normalized integers in 8-,10-,16-,24-, and 32-bit variants. Both models offer a finite sequence of "grid-points". The obvious difference between the two models is that the fixed-point model offers a constant spacing between values in the normalized range of [0,1] or [-1,1], while the floating point model allows for smaller "deltas" as you get closer to 0, and larger "deltas" the further you are away from 0.
To add some context, let me define a struct as an example:
struct VertexData { float[3] position; //3x32-bits float[2] texCoord; //2x32-bits float[3] normals; //3x32-bits } //Total of 32 bytes Every vertex gets a position, a coordinate on my texture, and a normal to do some light calculations. In this case we have 8x32=256bits per vertex. Since the texture coordinates lie in the interval [0,1] and the normal vector components are in the interval [-1,1] it would seem useful to use normalized representation as suggested in the topic linked at the top of the post. The texture coordinates might as well be represented in a fixed-point model, because it seems most useful to be able to sample the texture in a uniform manner, as the pixels don't get any "denser" as we get closer to 0. In other words the "delta" does not need to become any smaller as the texture coordinates approach (0,0). A similar argument can be made for the normal-vector, as a normal vector should be normalized anyway, and we want as many points as possible on the sphere around (0,0,0) with a radius of 1, and we don't care about precision around the origin. Even if we have large textures such as 4k by 4k (or the maximum allowed by D3D11, 16k by 16k) we only need as many grid-points on one axis, as there are pixels on one axis. An unsigned normalized 14 bit integer would be ideal, but because it is both unsupported and impractical, we will stick to an unsigned normalized 16 bit integer. The same type should take care of the normal vector coordinates, and might even be a bit overkill.
struct VertexData { float[3] position; //3x32-bits uint16_t[2] texCoord; //2x16bits uint16_t[3] normals; //3x16bits } //Total of 22 bytes Seems like a good start, and we might even be able to take it further, but before we pursue that path, here is my first question: can the GPU even work with the data in this format, or is all I have accomplished minimizing CPU-side RAM usage? Does the GPU have to convert the texture coordinates back to a floating-point model when I hand them over to the sampler in my pixel shader? I have looked up the data types for HLSL and I am not sure I even comprehend how to declare the vertex input type in HLSL. Would the following work?
struct VertexInputType { float3 pos; //this one is obvious unorm half2 tex; //half corresponds to a 16-bit float, so I assume this is wrong, but this the only 16-bit type I found on the linked MSDN site snorm half3 normal; //same as above } I assume this is possible somehow, as I have found input element formats such as: DXGI_FORMAT_R16G16B16A16_SNORM and DXGI_FORMAT_R16G16B16A16_UNORM (also available with a different number of components, as well as different component lengths). I might have to avoid 3-component vectors because there is no 3-component 16-bit input element format, but that is the least of my worries. The next question would be: what happens with my normals if I try to do lighting calculations with them in such a normalized-fixed-point format? Is there no issue as long as I take care not to mix floating- and fixed-point data? Or would that work as well? In general this gives rise to the question: how does the GPU handle fixed-point arithmetic? Is it the same as integer-arithmetic, and/or is it faster/slower than floating-point arithmetic?
Assuming that we still have a valid and useful VertexData format, how far could I take this while remaining on the sensible side of what could be called optimization? Theoretically I could use the an input element format such as DXGI_FORMAT_R10G10B10A2_UNORM to pack my normal coordinates into a 10-bit fixed-point format, and my verticies (in object space) might even be representable in a 16-bit unsigned normalized fixed-point format. That way I could end up with something like the following struct:
struct VertexData { uint16_t[3] pos; //3x16bits uint16_t[2] texCoord; //2x16bits uint32_t packedNormals; //10+10+10+2bits } //Total of 14 bytes Could I use a vertex structure like this without too much performance-loss on the GPU-side? If the GPU has to execute some sort of unpacking algorithm in the background I might as well let it be. In the end I have a functioning deferred renderer, but I would like to reduce the memory footprint of the huge amount of vertecies involved in rendering my landscape.
TLDR: I have a lot of vertices that I need to render and I want to reduce the RAM-usage without introducing crazy compression/decompression algorithms to the CPU or GPU. I am hoping to find a solution by involving fixed-point data-types, but I am not exactly sure how how that would work.