General Structure #

In this section, we discuss the general structure of our game which we will use as a base for future chapters.

Entry Point #

On Xbox 360, the runtime environment looks for a void function named main with no arguments and a __cdecl¹ calling convention as the application’s entry point. This reflects the fixed execution model of the Xbox’s OS, which—unlike desktop Windows—does not provide command-line arguments or environment variables. This is similar to how embedded or tool-style Windows programs operate, as seen in Microsoft’s own Cryptography API examples².

void __cdecl main() {
	// ...
}

Structures #

In our example code, we include two structures: Vertex and Time. These structs facilitate encapsulation of data, without hiding key implementation details.

struct Vertex {
	float position[3];
	DWORD color;
};

struct Time {
	LARGE_INTEGER previousFrameTime;
	LARGE_INTEGER totalElapsedTicks;
	
	float totalTimeSinceLaunch;
	float deltaTime;
	float secondsPerTick;
};

Vertex is used to help marshal data between the Xbox 360’s CPU and GPU, and Time is used for general time bookkeeping and is very useful for physics/rendering updates.

Pre-Compiled Header #

When developing a title for the Xbox 360 it was highly recommended to use a pre-compiled header in an effort to reduce compilation times. By default, the pre-compiled header file’s name will be stdafx.h and is intended for including frequently used but rarely changed headers, such as system headers. This header is accompanied by a source file with a similar name - stdafx.cpp which is used to simply include the header file.

Ensure stdafx.h is included above all other includes in every source file, for example:

// Renderer.cpp
#include "stdafx.h"
#include "Renderer.hpp"

Renderer::Renderer() {
		// ...
}

In the source code just shown, we are imagining that we have a Renderer class split into an interface and implementation (header and source) file.

Implementation Rationale #

In the first chapters, code will be written in a single main.cpp file. This way the usefulness of the code is hopefully maximised, and as the code we write begins to grow in size and complexity, we will make suggestions for classes/structures to help better organise the code.