From b9be995232e8299d504e7898a9d6c5384664b8ee Mon Sep 17 00:00:00 2001
From: Kevin Chabowski <kevin@kch42.de>
Date: Sun, 11 Aug 2013 23:01:55 +0200
Subject: Initial commit.

Reading maps is already working :-D
---
 mcmap/chunk.go | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 mcmap/chunk.go

(limited to 'mcmap/chunk.go')

diff --git a/mcmap/chunk.go b/mcmap/chunk.go
new file mode 100644
index 0000000..22f9dfa
--- /dev/null
+++ b/mcmap/chunk.go
@@ -0,0 +1,81 @@
+package mcmap
+
+import (
+	"errors"
+	"github.com/kch42/gonbt/nbt"
+	"time"
+)
+
+func calcBlockOffset(x, y, z int) int {
+	if (x < 0) || (y < 0) || (z < 0) || (x >= 16) || (y >= 256) || (z >= 16) {
+		panic(errors.New("Can't calculate Block offset, coordinates out of range."))
+	}
+
+	return x + (z * 16) + (y * 256)
+}
+
+// BlockToChunk calculates the chunk (cx, cz) and the block position in this chunk(rbx, rbz) of a block position given global coordinates.
+func BlockToChunk(bx, bz int) (cx, cz, rbx, rbz int) {
+	cx = bx << 4
+	cz = bz << 4
+	rbx = ((cx % 16) + 16) % 16
+	rbz = ((cz % 16) + 16) % 16
+	return
+}
+
+// ChunkToBlock calculates the global position of a block, given the chunk position (cx, cz) and the plock position in that chunk (rbx, rbz).
+func ChunkToBlock(cx, cz, rbx, rbz int) (bx, bz int) {
+	bx = cx*16 + rbx
+	bz = cz*16 + rbz
+	return
+}
+
+// Chunk represents a 16*16*256 Chunk of the region.
+type Chunk struct {
+	Entities []nbt.TagCompound
+
+	x, z int32
+
+	lastUpdate      int64
+	populated       bool
+	inhabitatedTime int64
+	ts              time.Time
+
+	heightMap            []int32 // Note: Ordered ZX
+	blockLight, skyLight []byte  // Note: Ordered YZX, only half-bytes
+
+	modified bool
+	blocks   []Block // NOTE: Ordered YZX
+	biomes   []Biome // NOTE: Orderes XZ
+}
+
+// MarkModified needs to be called, if some data of the chunk was modified.
+func (c *Chunk) MarkModified() { c.modified = true }
+
+// Coords returns the Chunk's coordinates.
+func (c *Chunk) Coords() (X, Z int32) { return c.x, c.z }
+
+// Block gives you a reference to the Block located at x, y, z. If you modify the block data, you need to call the MarkModified() function of the chunk.
+//
+// x and z must be in [0, 15], y in [0, 255]. Otherwise a nil pointer is returned.
+func (c *Chunk) Block(x, y, z int) *Block {
+	off := calcBlockOffset(x, y, z)
+	if off < 0 {
+		return nil
+	}
+
+	return &(c.blocks[off])
+}
+
+// Height returns the height at x, z.
+//
+// x and z must be in [0, 15]. Height will panic, if this is violated!
+func (c *Chunk) Height(x, z int) int {
+	if (x < 0) || (x > 15) || (z < 0) || (z > 15) {
+		panic(errors.New("x or z parameter was out of range"))
+	}
+
+	return int(c.heightMap[z*16+x])
+}
+
+// TODO: func (c *Chunk) RecalcHeightMap()
-- 
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