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GTE Tool Set

The Generic Tile Engine (GTE) Tool Set enables tile-based games to be implemented in an efficient manner. The tool set provides support for sprites, animations, large scrolling backgrounds and special effects.

To effectively use this tool set, a user should be familiar with the following

  • The IIgs Hardware Reference
  • The QuickDraw II tool set
  • IIgs Technical Note #70

A preview of the GTE Tool Set routines

To introduce you to the capabilities of the GTE Tool Set the routines are grouped by function and briefly described in Table 1. These routines are descibed in detail later where they are separated into housekeeping routines (discussed in routine number order) and the rest of the GTE Tool Set routines (discussed in alphabetical order).

Table 1
GTE Tool Set routines and their functions
Routine Description
Housekeeping Routines
GTEBootInitInitializes the GTE Tool Set; called only by the Tool Locator — must not be called by an application
GTEStartUpStarts up the GTE Tool Set for use by an application
GTEShutDownShuts down the GTE Tool Set when an application quits
GTEVersionReturns the version number of the GTE Tool Set
GTEResetResets the GTE Tool Set; called only when the system is reset — must not be called by an application
GTEStatusIndicates whether the GTE Tool Set is active
Sprite Routines
GTECreateSpriteStamp Creates a sprite stamp from the tile set
GTEAddSpriteAdd a active sprite to the scene
GTEMoveSpriteChanges a sprite's location
GTEUpdateSpriteChanges a sprite's tile set reference and display flags
GTERemoveSprite Removes a sprite from the scene
Tile Routines
GTELoadTileSetCopies a tileset into the GTE tileset memory
GTESetTileAssigns a tile to a tile store
GTEGetTileAtRetrieves the tile ID stored in the tile store
GTECopyTileToDynamicCopies a tile from the tileset memory into the managed dynamic tile memory. Changing the dynamic tile data will result in all of the tiles updating on the next call the GTERender()
GTEGetTileDataAddrReturns the base address of the tiledata memory
GTEFillTileStoreFills the entire tile store with a tile ID.
Primary Background Routines
GTESetBG0OriginSets the upper-left origin point in the primary background
GTERenderDraws the current scene to the graphics screen
GTEGetBG0TileMapInfoReturns a record describing the number of tiles in the primary tilemap and a pointer to the tilemap data.
GTESetBG0TileMapInfoDefines a tile map for the primary background
GTERefreshForces all of the tiles in the tile store to be refreshed on the next render.
Secondary Background Routines
GTESetBG1OriginSets the upper-left origin point in the secondary background
GTECopyPicToBG1Copies an uncompressed pixel image into the secondard background buffer
GTESetBG1TileMapInfoDefines a tile map for the secondary background
Timer Routines
GTEAddTimerAdd a timer callback that is fired after a designated number of VBL ticks
GTERemoveTimerRemoves an active timer
GTEStartScriptRegisters a GTE script to be handled in the background
Overlay Routines
GTESetOverlayRegisters an overlay routine to be integrated into the renderer. Typically used for status bars or messages.
GTEClearOverlayRemoves the current overlay from the renderer
Functions affecting the global state
GTESetScreenModeSets the playing field's port rectangle to a pre-defined size, or a specified width and height
GTESetPaletteCopies a palette to the Super HiRes palette memory
GTEBindSCBArrayTakes an array of SCB bytes and binds them to either the Primary or Secondary background's vertical position
GTEGetScreenInfoReturns a records describing the origin, width and height of the playfield on the physical graphics screen.
Misc. Functions
GTEReadControlReads the keyboard and returns key events in a gamepad structure
GTEGetSecondsReturns the number of seconds elapsed since the toolset was started

Using the GTE Tool Set

This section discusses how the GTE Tool Set routines fit into the general flow of an application and gives you an idea of which routines you'll need to use under normal circumstances. Each routine is described in detail later in this chapter.

The GTE Tool Set depends on the presence of the tool sets shown in Table 2 and requires at least the indicated version of each tool set be present.

Table 2
GTE Tool Set — other tool sets required
Tool set numberTool set nameMinimal version needed
$01#01Tool Locator3.x
$02#02Memory Manager3.x
$03#03Miscellaneous Tool Set3.2
$06#06Event Manager3.1

To use the GTE Tool Set routines, your application must call the GTEStartUp routine before making any other GTE calls. To save memory, the GTE Tool Set may be started up with some features disabled. See the section GTEStartUp in this chapter for further details.

Your application should also make the GTEShutDown call when the application quits.

$01XX

GTEBootInit

Initializes the GTE Tool Set; called only by the Tool Locator.

An application must never make this call

Parameters

The stack is not affected by this call. There are no input or output parameters.

Errors

None

C

Call must not be made by an application.

$02XX

GTEStartUp

Starts up the GTE Tool Set for use by an application.

Your application must make this call before it makes any other GTE Tool Set calls.

The GTE Tool Set uses two consecutive pages of bank zero for its direct page space starting at dPageAddr. If the ENGINE_MODE_DYN_TILES flag is set in the capFlags, the GTE will attempt to allocate an additional eight pages of bank zero space. If the ENGINE_MODE_BNK0_BUFF flag is set, then GTE will attempt to allocate an ~32KB buffer from $2000 to $9CFF in Bank 0.

Parameters
Stack before call
previous contents
dPageAddrWord16-bit address of two pages of page-aligned Bank 0 memory
capFlagsWordCapability flags to set the engine mode
userIDWordApplication word returned by the Memory Manager. All memory allocated by GTE will use this userId
SP
Stack after call
previous contents
SP
capFlags
ENGINE_MODE_TWO_LAYER $0001 Enables the second background layer. This will have a moderate impact on rendering performance.
ENGINE_MODE_DYN_TILES $0002 Enables the use of dynamic (animated) tiles. This will have a small impact on performance and requires allocating 8 pages of Bank 0 memory
ENGINE_MODE_BNK0_BUFF $0004 Allocates a 32KB buffer in Bank 0 for advanced graphical effects and customizations.
Errors
Memory Manager ErrorsReturned unchanged
C
extern pascal GTEStartUp(dPageAddr, capFlags, userID)
Word dPageAddr
Word capFlags
Word userID

$03XX

GTEShutDown

Parameters

The stack is not affected by this call. There are no input or output parameters.

Errors

None

C

extern pascal void GTEShutDown()

$04XX

GTEVersion

Returns the version number of the GTE Tool Set.

Parameters
Stack before call
previous contents
wordspaceWord — Space for result
SP
Stack after call
previous contents
versionInfoWord — Version number of the GTE Tool Set.
SP
Errors

None

C

extern pascal Word GTEVersion()

$05XX

GTEReset

Resets the GTE Tool Set; called only when the system is reset.

An application must never make this call

Parameters

The stack is not affected by this call. There are no input or output parameters

Errors

None

C

Call must not be made by an application.

$06XX

GTEStatus

Indicates whether the GTE Tool Set is active.

Parameters
Stack before call
previous contents
wordspaceWord — Space for result
SP
Stack after call
previous contents
activeFlagWord — BOOLEAN; TRUE if GTE Tool Set active, FALSE if inactive
SP
Errors

None

C

extern pascal Boolean GTEStatus()

GTE Tool Set routines

$09XX

GTEGetAddress

Returns the address of an internal GTE Tool Set array.

Stack before call
previous contents
addrIdWORD — INTEGER id
longspaceLong — Space for result
SP
Stack after call
previous contents
addressLong — POINTER to data structure
SP
Errors
$XX04gteBadAddressThe id is invalid
C
extern pascal Pointer GTEGetAddress(id)
Word         id
  

$0CXX

GTENewSprite

Allocates space for a new sprite and compiles it based on the pixel data in the locInfoPtr arguement. The sprite flags word is used to enable or disable certain capabilities. If an application does not need the all the features enabled, features may be disabled to save memory and slightly increase performance.

Parameters
Stack before call
previous contents
ptrToDataLocInfoLong — POINTER to data location information.
ptrToDataRectLong — POINTER to a Rect that defines the sprite bounds.
ptrToMaskLocInfoLong — POINTER to mask location information; may be nil.
ptrToMaskRectLong — POINTER to a Rect that defines the sprite bounds; may be nil.
spriteFlagsWord — INTEGER; sprite flags
longspaceLong — Space for result
SP
Stack after call
previous contents
spriteHandleLong — HANDLE to new sprite
SP
Errors

None

C
extern pascal SpriteHandle GTENewSprite(data, mask, spriteFlags)
locInfoPtr   data
locInfoPtr   mask
Word         spriteFlags
  

Sprite Flags

The values available for spriteFlags are shown in Figure ??-??.

1514131211109876543210

Bits 0spriteTypeReserved; must be zero
Bit 1fNoHFlipDo not create a horizontally flipped version of the sprite. Setting the horizontal flip bit in the Object Attribute Memory will have no effect.
Bit 2fNoVFlipDo not create a vertically flipped version of the sprite. Setting the vertical flip bit in the Object Attribute Memory will have no effect.
Bit 3fNoPriorityDo not generate code to honor the field mask. Seting the priority bit in the Object Attribute Memory will have no effect.
Bit 4fNoMask This sprite will not clip itself to the playing fields. This is potentially dangerous since, if the sprite move off screen, it may corrupt system memory. Only use this bit if the sprite will never leave the playing field.
Bits 5-15Reservedmust be zero.

$0DXX

GTEDisposeSprite

Parameters
Stack before call
previous contents
spriteHandleLong — Handle to a sprite returned by GTENewSprite.
SP
Stack after call
previous contents
SP
Error

None

C
extern pascal void GTEDisposeSprite(spriteHndl)
Handle       spriteHndl

$0FXX

GTENewTile

Allocates space for a new tile and compiles it based on the pixel data referenced by the locInfoPtr arguements. If the mask infoRecPtr is nil, then the mask is computed using the current backgound color. The mask is only used when the tile map specifies the tile to be drawn at high priority.

Parameters
Stack before call
previous contents
ptrToDataLocInfoLong — POINTER to data location information.
ptrToDataOriginLong — POINTER to Point that marks the top-left corner.
ptrToMaskLocInfoLong — POINTER to mask location information; may be nil.
ptrToMaskOriginLong — POINTER to Point that marks the top-left corner; may be nil.
longspaceLong — Space for result
SP
Stack after call
previous contents
tileHandleLong — HANDLE to new tile
SP
Erros

None

C
extern pascal TileHandle GTENewTile(ptrToDataLocInfo, ptrToDataOrigin, ptrToMaskLocInfo, ptrToMaskOrigin)
locInfoPtr   ptrToDataLocInfo
Point*       ptrToDataOrigin
locInfoPtr   ptrToMaskLocInfo
Point*       ptrToMaskOrigin
  

$10XX

GTEDisposeTile

Parameters
Stack before call
previous contents
tileHandleLong — Handle to a tile returned by GTENewTile.
SP
Stack after call
previous contents
SP
Error

None

C
extern pascal void GTEDisposeTile(tileHandle)
Handle       tileHandle

$11XX

GTESetTile

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

$12XX

GTEGetTile

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

Buffer Functions

GTESetBG0Fringe

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTESetBG0Mask

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTESetBG0Dynamic

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTESetBG0Palettes

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTESetBG0Origin

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTESetBG1Tiles

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTESetBG1Origin

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTERefreshAll

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTERefreshBG0

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTERefreshBG1

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

I/O Functions

GTELoadAPF

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTELoadBMP

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTELoadSHR

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern

GTELoadFile

Parameters
Stack before call
previous contents
SP
Stack after call
previous contents
SP
Errors

None

C
extern