ml
104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
package level
|
|
|
|
const (
|
|
// ObjectCrossReferenceEntrySize describes the size, in bytes, of a ObjectCrossReferenceEntry.
|
|
ObjectCrossReferenceEntrySize = 10
|
|
|
|
defaultObjectCrossReferenceEntryCount = 1600
|
|
)
|
|
|
|
func offMapReferencePosition() TilePosition {
|
|
return TilePosition{X: 0xFF, Y: 0}
|
|
}
|
|
|
|
// ObjectCrossReferenceEntry links objects and tiles.
|
|
type ObjectCrossReferenceEntry struct {
|
|
TileX int16
|
|
TileY int16
|
|
|
|
ObjectID ObjectID
|
|
NextInTile int16
|
|
NextTileForObj int16
|
|
}
|
|
|
|
// TilePosition returns the position for that entry.
|
|
func (entry ObjectCrossReferenceEntry) TilePosition() TilePosition {
|
|
return TilePosition{
|
|
X: byte(entry.TileX),
|
|
Y: byte(entry.TileY),
|
|
}
|
|
}
|
|
|
|
// SetTilePosition sets the position for that entry.
|
|
func (entry *ObjectCrossReferenceEntry) SetTilePosition(pos TilePosition) {
|
|
if pos == offMapReferencePosition() {
|
|
entry.TileX = -1
|
|
entry.TileY = 0
|
|
} else {
|
|
entry.TileX = int16(pos.X)
|
|
entry.TileY = int16(pos.Y)
|
|
}
|
|
}
|
|
|
|
// Reset clears the members of the entry.
|
|
func (entry *ObjectCrossReferenceEntry) Reset() {
|
|
*entry = ObjectCrossReferenceEntry{}
|
|
}
|
|
|
|
// ObjectCrossReferenceTable is a list of entries.
|
|
// The first entry is reserved for internal use. For the reserved entry,
|
|
// The NextInTile member refers to the head of the single-linked free chain.
|
|
type ObjectCrossReferenceTable []ObjectCrossReferenceEntry
|
|
|
|
// DefaultObjectCrossReferenceTable returns an initialized table with a default size.
|
|
func DefaultObjectCrossReferenceTable() ObjectCrossReferenceTable {
|
|
table := make(ObjectCrossReferenceTable, defaultObjectCrossReferenceEntryCount)
|
|
table.Reset()
|
|
return table
|
|
}
|
|
|
|
// Reset wipes the entire table and initializes all links.
|
|
func (table ObjectCrossReferenceTable) Reset() {
|
|
tableLen := len(table)
|
|
for i := 0; i < tableLen; i++ {
|
|
entry := &table[i]
|
|
entry.Reset()
|
|
entry.NextInTile = int16(i + 1)
|
|
}
|
|
if tableLen > 0 {
|
|
table[tableLen-1].NextInTile = 0
|
|
}
|
|
}
|
|
|
|
// Allocate attempts to reserve a free entry in the table and return its index.
|
|
// Returns 0 if exhausted.
|
|
func (table ObjectCrossReferenceTable) Allocate() int {
|
|
if len(table) < 2 {
|
|
return 0
|
|
}
|
|
start := &table[0]
|
|
if start.NextInTile == 0 {
|
|
return 0
|
|
}
|
|
index := start.NextInTile
|
|
entry := &table[index]
|
|
start.NextInTile = entry.NextInTile
|
|
|
|
entry.Reset()
|
|
|
|
return int(index)
|
|
}
|
|
|
|
// Release frees the entry with given index.
|
|
func (table ObjectCrossReferenceTable) Release(index int) {
|
|
if (index < 1) || (index >= len(table)) {
|
|
return
|
|
}
|
|
start := &table[0]
|
|
entry := &table[index]
|
|
|
|
entry.Reset()
|
|
entry.NextInTile = start.NextInTile
|
|
start.NextInTile = int16(index)
|
|
}
|