Game Objects and Event Loop

Files
file	blitter.cpp
	Blitting algorithms for the SpriteManager.
file	sprite.cpp
	Function implementations for Sprite.
file	sprite.h
	Class definition for Sprite.
file	spriteloader.cpp
	Function implementations for SpriteLoader.
file	spriteloader.h
	Class definition for SpriteLoader.
file	spritemanager.cpp
	Function implementations for SpriteManager.
file	spritemanager.h
	Class definition for SpriteManager.
Classes
class	Sprite
	The basic Sprite class itself. More...
class	SpriteLoader
	Class to handle loading all necessary data for a sprite. More...
class	SpriteManager
	Class to manage movement, collision, and drawing of sprites. More...
Sprite flags
Functions of the various sprite flags
#define	SPRITE_NONE   0x0000
	No flags.
#define	SPRITE_WAIT   0x0001
	Sprite is waiting for first draw or removal from list.
#define	SPRITE_MOVED   0x0002
	Sprite needs redraw.
#define	SPRITE_EXPIRED   0x0004
	Sprite needs removal from list.
#define	SPRITE_DELETEABLE   0x0008
	Sprite can be freed from mem upon removal from list.
#define	SPRITE_OWNSURFACE   0x0010
	Sprite owns aka can free the contained SDL_surface.
#define	SPRITE_OWNBITMASK   0x0020
	Sprite owns aka can free the contained bitmasks.
SpriteManager flags
Flags to control the behavior of SpriteManager
#define	MAX_RECTS   512
	Maximum number of rectangles in draw-stack.
#define	SM_NONE   0x0000
	No flags.
#define	SM_RUNNING   0x0001
	SpriteManager is running.
#define	SM_TOTALREDRAW   0x0002
	SpriteManager needs to totally redraw screen.
#define	SM_PAUSED   0x0004
	SpriteManager is paused.
#define	SM_OWNBG   0x0008
	SpriteManager owns the background surface.
#define	SM_DOUBLEBUF   0x0010
	Spritemanager must do full screen flips.
Defines
#define	COL_LAYER(x)   (0xff&(1<<x))
	Converts a collision layer to a collision mask.
#define	SLASH   "/"
	Most sane systems use forward-slashes.
Typedefs
typedef Uint16	SpriteFlag
	Type used for sprite status flag.
typedef Uint8	ColType
	Type used for collision layer.
Enumerations
enum	SMRun_Return { SMRUN_OK = 0, SMRUN_TIMESTEP }
	Return values for SpriteManager::Run(). More...
Functions
SDL_Surface *	LoadConvertBMP (const char *fname, Uint8 tr, Uint8 tg, Uint8 tb)
	Loads an image and converts it to screen parameters.
bitmask *	MakeBitMask (SDL_Surface *surf, Rect rect)
	Converts selected portion of image into collision bitmask.
char *	SprMakePath (const char *filename, const char *path, char *buf)
	Function to assemble a full path from a path and filename.

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Detailed Description

The core of spritelib consists of a generic sprite engine, consisting of Sprites, which are game objects with positions, velocity, image frames, and collision attributes, and SpriteManager, a generic game loop framework. These objects work together to simplify the work of building a sprite-based game, and abstract away the complexities of efficient blitting.

Sounds really complicated, but it's not. Basically, you have a SpriteManager object, which contains a bunch of Sprite objects. The SpriteManager runs a game loop, which continues looping until an SDL quit message is recieved; this loop reads events, moves sprites, and redraws the screen.

You need not concern yourself with the low-level handling of movement, events, or collision - Sprite and SpriteManager handle all of these. To create custom sprite behavior, simply overload Sprite::Update() and do as you wish. There are many simple overloadable operatires in SpriteManager as well, take a look.

And for creating the sprites, SpriteLoader helps a LOT, by using external configuration files to define certain sprite parameters(like graphics and collision) instead of needing to hardcode them - it takes the mess out of sight unless it needs to be seen, and allows you to modify sprite parameters and graphics significantly without needing to recompile.

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Define Documentation

#define SPRITE_WAIT   0x0001

Prevents a potential race condition; if a sprite's Update() member causes more sprites to be added to a list of sprites, which cause more, and so forth. This flag prevents brand-new sprites from being considered for collision and movement until the NEXT frame. Definition at line 90 of file sprite.h. Referenced by Sprite::Init_Flags(), SpriteManager::Move(), and Sprite::New().

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Enumeration Type Documentation

enum SMRun_Return

Enumeration values: SMRUN_OK  Normal termination of Run() due to SDL_QUIT or flag clear. SMRUN_TIMESTEP  Timestep error - timestep too small or CPU power insufficient. Definition at line 61 of file spritemanager.h. Referenced by SpriteManager::Run().

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Function Documentation

SDL_Surface* LoadConvertBMP (  const char *  fname, Uint8  tr, Uint8  tg, Uint8  tb )

Loads an image file and converts it to local format. Definition at line 390 of file sprite.cpp. Referenced by SpriteLoader::Load(), and SpriteManager::SpriteManager().

bitmask* MakeBitMask (  SDL_Surface *  surf, Rect  rect )

Turns a portion of an image to a collision mask. Needs SDL_SRCCOLORKEY to be set. Definition at line 347 of file sprite.cpp. References getpixel(). Referenced by Sprite::Init_Bitmask(), and SpriteLoader::Load().

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char* SprMakePath (  const char *  filename, const char *  path, char *  buf )

Attempts to assemble a full path from a relative offset and a filename. Definition at line 419 of file spriteloader.cpp. References lastchar(), and SLASH. Referenced by SpriteLoader::Load().

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