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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 After cloning, an $ORX environment variable will be created automatically for your system which will help with making game projects much easier. It will also create several IDE projects for your operating system: Visual Studio, Codelite, Code::Blocks, and gmake. These Orx projects will allow you to compile the Orx library for use in your own projects. And the$ORX environment variable means that your projects will know where to find the Orx library.
For more details on this step, visit http://orx-project.org/wiki/en/tutorials/cloning_orx_from_github at the Orx learning wiki.
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. 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. • Hi Guys, really pleased to announce that my 5 part series on creating a 2D UFO game using the Orx Portable Game Engine has been published in the articles section. The series is designed to help beginners download Orx, then use the tools to create your first project in your favourite IDE/OS. It then takes you step by step through numerous topics: Creating a playfield The ufo movement Keyboard controls Collisions Physics Scores Sounds and; Shadows The series starts over here: How to write a 2D UFO game using the Orx Portable Game Engine - Part 1 If you find any problems, or enjoyed going through it, I'd love to hear about it. Graphics for the article series were kindly designed by my friend FullyBugged. • Hello my name is Erik Reis i'm 15 and i just got into game development. I don't want to spend hundreds of bucks on online classes i just want someone to help me. Kinda like a mentor or another new developer I can learn with. I'm young and i'm new and stupid and would love to learn this is just don't know where to start there is so much. I do know some basic C# and i want to use unity. I can do some pixel art though it is not up to the standard i would like but that can be improved. I would really enjoy to meet someone who has knowledge of the subject and can teach me on their spare time. Thanks i really appreciate if your read this post. • Here is the scenario I have pertaining to a combat system I am jotting down on paper. The attacker has 100 soldiers each with 1 attack point and 3 health points. The defender has the same. All the player has to do is press a button and combat is all computed then the player is just shown the results. From my current example, I would have the attacker's soldiers do 100 points of damage to the defender resulting in 33 defenders being killed. The same happens to the attacker's soldiers. This continues until both sides defeat each other at the same time and it ends in a draw. I feel if I introduce a random factor, the battle could get lop-sided and the smaller side could not recover So I thought I would ask the community for their opinions of the very simple combat scenario. The game concept I am designing deals with combat from outside the actual conflict. Sort of like a coach and a sports team. You give orders and watch as your units perform them. The game does start small, with 100 to 200 soldiers (all the same) and could grow to larger numbers as well. I was just wanting to get a system in place for small conflict that could scale into larger ones. Each side has a unit type (soldier) a unit quantity (100). The player give the order, and the computer does the rest. After both players give their orders, the results are computed instantly. Keeping all things equal, Attack power, defensive power, etc. (I need a baseline) What would be the best way to determine damage? Static numbers, or RNG numbers? To use or not use RNG in combat? • By simco50 Hello, I've stumbled upon Urho3D engine and found that it has a really nice and easy to read code structure. I think the graphics abstraction looks really interesting and I like the idea of how it defers pipeline state changes until just before the draw call to resolve redundant state changes. This is done by saving the state changes (blendEnabled/SRV changes/RTV changes) in member variables and just before the draw, apply the actual state changes using the graphics context. It looks something like this (pseudo): void PrepareDraw() { if(renderTargetsDirty) { pD3D11DeviceContext->OMSetRenderTarget(mCurrentRenderTargets); renderTargetsDirty = false } if(texturesDirty) { pD3D11DeviceContext->PSSetShaderResourceView(..., mCurrentSRVs); texturesDirty = false } .... //Some more state changes } This all looked like a great design at first but I've found that there is one big issue with this which I don't really understand how it is solved in their case and how I would tackle it. I'll explain it by example, imagine I have two rendertargets: my backbuffer RT and an offscreen RT. Say I want to render my backbuffer to the offscreen RT and then back to the backbuffer (Just for the sake of the example). You would do something like this: //Render to the offscreen RT pGraphics->SetRenderTarget(pOffscreenRT->GetRTV()); pGraphics->SetTexture(diffuseSlot, pDefaultRT->GetSRV()) pGraphics->DrawQuad() pGraphics->SetTexture(diffuseSlot, nullptr); //Remove the default RT from input //Render to the default (screen) RT pGraphics->SetRenderTarget(nullptr); //Default RT pGraphics->SetTexture(diffuseSlot, pOffscreenRT->GetSRV()) pGraphics->DrawQuad(); The problem here is that the second time the application loop comes around, the offscreen rendertarget is still bound as input ShaderResourceView when it gets set as a RenderTargetView because in Urho3D, the state of the RenderTargetView will always be changed before the ShaderResourceViews (see top code snippet) even when I set the SRV to nullptr before using it as a RTV like above causing errors because a resource can't be bound to both input and rendertarget. What is usually the solution to this? Thanks! • Advertisement • Advertisement # DX11 I need to learn DirectX. The examples for Introduction to 3D Programming with DirectX 11 by Frank D Luna does not work. Can anyone help me ## Recommended Posts I have to learn DirectX for a course I am studying. This book https://www.amazon.co.uk/Introduction-3D-Game-Programming-Directx/dp/1936420228 I felt would be great for me to learn from. The trouble is the examples which are all offered here http://www.d3dcoder.net/d3d11.htm . They do not work for me. This is a known issue as there is a link on the examples page saying how to fix it. I'm having difficulty with doing this though. This is the page with the solution http://www.d3dcoder.net/Data/Book4/d3d11Win10.htm. The reason why this problem is happening, the book was released before Windows 10 was released. Now when the examples are run they need slight fixes in order for them to even work. I just can't get these examples working at all. Would anyone be able to help me get the examples working please. I am running Windows 10 also just to make this clear, so this is why the examples are experiencing the not so desired behaviour. I just wish they would work straight away but there seems to be issues with the examples from this book mainly because of it trying to run from a Windows 10 OS. On top of this, if anyone has any suggestions with how I can learn DirectX 11 i would be most grateful. Thanks very much. I really would like to get them examples working to though from the book I mentioned. Look forward to reading any replies this thread receives. GameDevCoder. PS - If anyone has noticed. I asked this about 1 year ago also but this was when I was dabbling in it. Now I am actually needing to produce some stuff with DirectX so I have to get my head round this now. I felt at the time that I sort of understood what was being written to me in response to my thread back then. I had always been a little unsure though of being absolutely sure of what was happening with these troublesome examples. So I am really just trying to get to the bottom of this now. If anyone can help me work these examples out so I can see them working then hopefully I can learn DirectX 11 from them. *SOLUTION* - I was able to get the examples running thanks to the gamedev.net community. Great work guys. I'm so please now that I can learn from this book now I have the examples running. Edited by GameDevCoder #### Share this post ##### Link to post ##### Share on other sites Advertisement Need more information than "They do not work for me". What's not working? #### Share this post ##### Link to post ##### Share on other sites Thanks for the reply. So, In order to getting these examples to work there needs to be some tweaks so they run normally again. From stuff in a topic I made about the same thing last year actually as I was just looking into this (preparation work) just then but am now needing to actually use DirectX so am really trying to get these examples working fine now. I have tried using some knowledge of which I acquired when I made a similar topic about a year ago now. Last night I was able to get working examples for chapter 1, 2, there isn't any for 3, chapter 4. One of the four examples in Chapter 6 I have working now to. If I can talk about an issue I'm having with one example for chapter 6. Here is what is stopping me run the Box example for chapter 6 right now. https://ibb.co/mQbPvw Prior to this like I have done similarly with the examples before to get them working for me: -Clicking in properties I go on VC++ Directories and change the include and library directories to include$(DXSDK_DIR), or where a 'common' folder is located that all the examples rely on.

- In Linker - Input. I remove d3dx11d.lib (in debug config), d3dx11.lib (in release), dxerr.lib (for both).

- Lastly I right click on the project and add existing item - I select from common folder 'dxerr.h and dxerr.cpp.

These steps allow for some examples to work. I'm having a problem with this box example though now and am not sure what to do.

Lastly, in some cases I might reconfigure so the common folder can be found like in c/c++ property page include directory. In the end I just try many ways in the hope I can get the examples working, I was given some instructions in the past how to get them working although I wasn't so confident that they worked flawlessly (i mean, it worked for one example but I wasn't sure they would work for other examples) or that I understood properly how they worked.

I hope this helps with explaining my predicament a bit more.

Any help would be so very much appreciated from the community. Thank you.

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15 hours ago, GameDevCoder said:

On top of this, if anyone has any suggestions with how I can learn DirectX 11 i would be most grateful.

I dont know anything about that book, but you can learn dx11 directly from MSDN and their dx11 samples work on windows 10 (I just checked them)

Direct3D Tutorial Win32 Sample - https://code.msdn.microsoft.com/Direct3D-Tutorial-Win32-829979ef
This is the classic tutorials 1-7 that take you from setting up a window to displaying a rotating textured cube. The download button is at the top of that page.
The zip file contains:
1. description.html
this has links for all 7 tutorial step by step descriptions. You should read all of these

2. A folder called c++
You can open this "Tutorials.sln" solution in visual studio (I use visual studio 2017), and let it update them all to the latest version of visual studio. Or you can open the projects in the folders which seems to also open all of them.
The sample contains all 7 tutorials. Compile them.
To run a particular sample (as the solution contains all), in the solution explorer of visual studio right click on the one you want eg "Tutorial07" and select "set as startup project". Then from the top menu select debug - start debugging.
I just checked it and it does work on windows 10, with visual studio 2017

********
After these 7 tutorials I recommend MSDN:

Direct3D 11 Graphics - https://msdn.microsoft.com/en-us/library/windows/desktop/ff476080(v=vs.85).aspx

HLSL - https://msdn.microsoft.com/en-us/library/windows/desktop/bb509561(v=vs.85).aspx

Edited by CortexDragon

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I think you need to download and install the legacy june 2010 directx SDK, because the bewerkt SDK's dont include d3dx11, which is used in luna's book and examples. You can find it on github, might need to build the libs (debug and release) yourself. Which should be relatively easy with some googling (if you've never did this before).

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16 minutes ago, cozzie said:

I think you need to download and install the legacy june 2010 directx SDK, because the bewerkt SDK's dont include d3dx11, which is used in luna's book and examples. You can find it on github, might need to build the libs (debug and release) yourself. Which should be relatively easy with some googling (if you've never did this before).

Hi. thank you. Yeah, I have installed the june 2010 directx sdk. I have had to do things with the debug and release also like removing some libraries that someone mentioned to me in the past. I appreciate your post.
If anyone can see the issue I'm having at the moment with the BOX example that isn't working. If anyone knows how them errors can be fixed? It was in regards to this https://ibb.co/mQbPvw  . Thanks forum.

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If you install and use the june 2010 SDK then you won't need to change anything.

edit - code that is.

Edited by Infinisearch

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1 minute ago, Infinisearch said:

If you install and use the june 2010 SDK then you won't need to change anything.

Interesting. I am just working through these examples now as it goes. Will see how I get on. Thanks for these post. Food for thought.

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Ok. I have removed a couple errors and am just left with one issue for the BOX example in chapter 6.

Does anyone know how I can fix this please?  https://ibb.co/gstKvw

Edited by GameDevCoder

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Not overly familiar with DirectXMath, and it has been quite a while since I was digging through the Luna DX11 book, but it looks like you probably need to use the constructor for XMFLOAT4, rather than rely on an implicit conversion