C++11 and “moving” data

Alright, time to get dirty in C++ land. We’re gonna talk about move semantics (also known as r-value references), one of the big new featuresets in C++11. Why do they matter? How do you use them?

Backstory: Copying vs Moving

Look at this code:
std::vector<MyClass> myCollection; MyClass myItem; myCollection.push_back(myItem);

When you run this code, you end up with two instances of MyClass that look the same: myItem, and myCollection[0], which is a copy of whatever myItem looked like at push_back() time.… Read the rest

Finding Stuff in 3D Space: An Overview

Let me tell you about a task that 3D games face a bunch. It’s a difficult task. That task is finding out what’s related to you in 3D space. It’s how you solve scenarios like these:

I’m a gravity well! I want to know all the triangles close to me so I can pull them towards me (cuz that’s what gravity does)!

… Read the rest

What the heck is COM?

You’re likely vaguely aware that COM exists and it’s important. But what the heck is COM?

Well:

COM stands for Component-Object Model.
It refers to a set of libraries and APIs, as well as the programming patterns required to use them.
Its goal is to provide a way for two separate programs with no prior knowledge of each other, possibly written in different languages or on different machines, to exchange data.

… Read the rest

Matrix Multiplication, A Novella: Chapter 4

So now you work at a video game company. That happened in between chapters.

That means you’re big league rolling! All those Khan Academy videos and Intro To Linear Algebra courses keep saying video games use matrices, and you’re gonna find out how.

So, most big-budget video games use 3D models (there’s 2D big-budget games, too, but fuck ’em).… Read the rest

Compiler-Generated Functions in C++

Let’s take a simple class:

class MyClass { public: int x; };

How many functions does MyClass have? None?

Oh, if only.

MyClass has four functions. These four default functions are generated by the compiler automatically. Here’s the functions and their behaviors:

CONSTRUCTOR: MyClass(). It’s called when you create an instance of your class. It calls the constructors of any base classes and member variables.

… Read the rest

Matrix Multiplication, A Novella: Chapter 3

There’s too many kids in the world!

See, you set up a great system going on for tracking a kid’s actions and determining how much coal or candy they get. It’s easy, and it’s foolproof. Why, it’s so good that Santa cut the budget for North Pole Behavior Psychology Lab, because he thinks you’re capable enough to do it without money.… Read the rest

Matrix Multiplication, A Novella: Chapter 2

Well, your days as an event planner are over. There was a lot of blood at Bacchanal S, and the police are looking for you. So you ditch town, fly to the North Pole, and find a job in Santa’s Behavior Psychology lab.

“Naughty” and “Nice” aren’t simple concepts, and Santa needs experts to determine which child is which.… Read the rest

Matrix Multiplication, A Novella: Chapter 1

So you got hired as an event planner. Congratulations on your new job!

You’re a clever event planner, and therefore you know that your events need tables for people to eat at. You rent tables per-event from your favorite party supply place, Vendor 1. Here’s the spreadsheet you use to track costs:
matrices-1

(I hope you didn’t just ignore that spreadsheet.… Read the rest

Let’s Talk About Cameras: Perspective and Field of View

[Note: This is technically part of the series on DirectX, but is readable on its own, and does not require programming experience to be understood.]

At the end of my previous post on rendering 3D scenes with DirectX, you were able to render an object, but you would only see a specific narrow area (-1 to +1 in X and Y, 0 to 1 in Z).… Read the rest

DirectX Part 4: Loading FBX Models

“Hey Ben”, you say, “these articles on DirectX are great!” (I know.) “But when you talked about vertices in your previous post, you had us hard-code an array of vertex information. I’m working with snooty artists who want to to use a graphical user interface to place thousands of triangles. Can I import a mesh from Maya?”… Read the rest