diff --git a/bot/world/chunk.go b/bot/world/chunk.go
index 5d339df..36fc3a1 100644
--- a/bot/world/chunk.go
+++ b/bot/world/chunk.go
@@ -103,11 +103,8 @@ type directSection struct {
 	data []uint64
 }
 
-func (d *directSection) GetBlock(x, y, z int) BlockStatus {
-	// According to wiki.vg: Data Array is given for each block with increasing x coordinates,
-	// within rows of increasing z coordinates, within layers of increasing y coordinates.
-	// So offset equals to ( x*16^0 + z*16^1 + y*16^2 )*(bits per block).
-	offset := (x + z*16 + y*16*16) * d.bpb
+func (d *directSection) GetBlock(offset int) BlockStatus {
+	offset *= d.bpb
 	padding := offset % 64
 	block := uint32(d.data[offset/64] >> padding)
 	if padding > 64-d.bpb {
@@ -117,8 +114,8 @@ func (d *directSection) GetBlock(x, y, z int) BlockStatus {
 	return BlockStatus(block & (1<<d.bpb - 1)) // mask
 }
 
-func (d *directSection) SetBlock(x, y, z int, s BlockStatus) {
-	offset := (x + z*16 + y*16*16) * d.bpb
+func (d *directSection) SetBlock(offset int, s BlockStatus) {
+	offset *= d.bpb
 	padding := offset % 64
 	mask := uint64(math.MaxUint64<<(padding+d.bpb) | (1<<padding - 1))
 	d.data[offset/64] = d.data[offset/64]&mask | uint64(s)<<padding
@@ -137,12 +134,8 @@ func (d *directSection) clone(bpb int) *directSection {
 		bpb:  bpb,
 		data: make([]uint64, 16*16*16*bpb/64),
 	}
-	for x := 0; x < 16; x++ {
-		for y := 0; y < 16; y++ {
-			for z := 0; z < 16; z++ {
-				newSection.SetBlock(x, y, z, d.GetBlock(x, y, z))
-			}
-		}
+	for offset := 0; offset < 16*16*16; offset++ {
+		newSection.SetBlock(offset, d.GetBlock(offset))
 	}
 	return newSection
 }
@@ -153,14 +146,14 @@ type paletteSection struct {
 	directSection
 }
 
-func (p *paletteSection) GetBlock(x, y, z int) BlockStatus {
-	v := p.directSection.GetBlock(x, y, z)
+func (p *paletteSection) GetBlock(offset int) BlockStatus {
+	v := p.directSection.GetBlock(offset)
 	return p.palette[v]
 }
 
-func (p *paletteSection) SetBlock(x, y, z int, s BlockStatus) {
+func (p *paletteSection) SetBlock(offset int, s BlockStatus) {
 	if i, ok := p.palettesIndex[s]; ok {
-		p.directSection.SetBlock(x, y, z, BlockStatus(i))
+		p.directSection.SetBlock(offset, BlockStatus(i))
 		return
 	}
 	i := len(p.palette)
@@ -172,5 +165,5 @@ func (p *paletteSection) SetBlock(x, y, z int, s BlockStatus) {
 		// So bpb+1 must enough for new len(p.palette).
 		p.directSection = *p.directSection.clone(p.bpb + 1)
 	}
-	p.directSection.SetBlock(x, y, z, BlockStatus(i))
+	p.directSection.SetBlock(offset, BlockStatus(i))
 }
diff --git a/bot/world/chunk_test.go b/bot/world/chunk_test.go
index c6b0acb..13b5fda 100644
--- a/bot/world/chunk_test.go
+++ b/bot/world/chunk_test.go
@@ -23,11 +23,11 @@ func TestDirectSection_clone(t *testing.T) {
 	s := newDirectSection(9)
 	dataset := randData(9)
 	for i := 0; i < 16*16*16; i++ {
-		s.SetBlock(i%16, i/16%16, i/16/16, dataset[i])
+		s.SetBlock(i, dataset[i])
 	}
 	s = s.(*directSection).clone(data.BitsPerBlock)
 	for i := 0; i < 16*16*16; i++ {
-		if s := s.GetBlock(i%16, i/16%16, i/16/16); dataset[i] != s {
+		if s := s.GetBlock(i); dataset[i] != s {
 			t.Fatalf("direct section error: want: %v, get %v", dataset[i], s)
 		}
 	}
@@ -48,13 +48,10 @@ func testSection(s Section, bpb int) func(t *testing.T) {
 	return func(t *testing.T) {
 		for _, dataset := range [][16 * 16 * 16]BlockStatus{secData(bpb), randData(bpb)} {
 			for i := 0; i < 16*16*16; i++ {
-				s.SetBlock(i%16, i/16%16, i/16/16, dataset[i])
+				s.SetBlock(i, dataset[i])
 			}
 			for i := 0; i < 16*16*16; i++ {
-				if v := s.GetBlock(i%16, i/16%16, i/16/16); dataset[i] != v {
-					//for i := 0; i < 18; i++ {
-					//	t.Log(s.(*paletteSection).directSection.GetBlock(i%16, i/16%16, i/16/16))
-					//}
+				if v := s.GetBlock(i); dataset[i] != v {
 					t.Fatalf("direct section error: want: %v, get %v", dataset[i], v)
 				}
 			}
diff --git a/bot/world/world.go b/bot/world/world.go
index f3d5a62..58a7e89 100644
--- a/bot/world/world.go
+++ b/bot/world/world.go
@@ -17,8 +17,17 @@ type Chunk struct {
 
 // Section store a 16*16*16 cube blocks
 type Section interface {
-	GetBlock(x, y, z int) BlockStatus
-	SetBlock(x, y, z int, s BlockStatus)
+	// GetBlock return block status, offset can be calculate by SectionOffset.
+	GetBlock(offset int) BlockStatus
+	// SetBlock is the reverse operation of GetBlock.
+	SetBlock(offset int, s BlockStatus)
+}
+
+func SectionOffset(x, y, z int) (offset int) {
+	// According to wiki.vg: Data Array is given for each block with increasing x coordinates,
+	// within rows of increasing z coordinates, within layers of increasing y coordinates.
+	// So offset equals to ( x*16^0 + z*16^1 + y*16^2 )*(bits per block).
+	return x + z*16 + y*16*16
 }
 
 type BlockStatus uint32
@@ -52,7 +61,7 @@ func (w *World) GetBlockStatus(x, y, z int) BlockStatus {
 	if c != nil {
 		// (n&(16-1)) == (n<0 ? n%16+16 : n%16)
 		if sec := c.Sections[y>>4]; sec != nil {
-			return sec.GetBlock(x&15, y&15, z&15)
+			return sec.GetBlock(SectionOffset(x&15, y&15, z&15))
 		}
 	}
 	return 0