glb

.gitignore

@@ -1 +1,2 @@
 *.gltf
+*.glb

cmd/stl2gltf.go

@@ -7,10 +7,13 @@ import (
 func main() {
 	stl := stl2gltf.Load("./example/0c448109-7ac9-4f6d-aaf6-ce6bb744032f.stl")
 	stl2gltf.Convert(stl, "./example/0c448109-7ac9-4f6d-aaf6-ce6bb744032f.gltf")
+	stl2gltf.ConvertGLB(stl, "./example/0c448109-7ac9-4f6d-aaf6-ce6bb744032f.glb")
 
 	stl = stl2gltf.Load("./example/1ec91891-c25a-4905-a79c-f3bc96045d37.stl")
 	stl2gltf.Convert(stl, "./example/1ec91891-c25a-4905-a79c-f3bc96045d37.gltf")
+	stl2gltf.ConvertGLB(stl, "./example/1ec91891-c25a-4905-a79c-f3bc96045d37.glb")
 
 	stl = stl2gltf.Load("./example/3ea057e5-1520-4898-a59c-f33a6c955bd7.stl")
 	stl2gltf.Convert(stl, "./example/3ea057e5-1520-4898-a59c-f33a6c955bd7.gltf")
+	stl2gltf.ConvertGLB(stl, "./example/3ea057e5-1520-4898-a59c-f33a6c955bd7.glb")
 }

convert.go

@@ -49,7 +49,7 @@ func Convert(stl STL, outFile string) {
 	}
 	indexBuf = padding(indexBuf)
 
-	log.Println(len(positionBuf), len(normalBuf), len(indexBuf))
+	log.Println("positions: ", len(positionBuf), " normals: ", len(normalBuf), " indices: ", len(indexBuf))
 
 	// concat
 	allData := make([]byte, 0)

convert_glb.go

@@ -0,0 +1,155 @@
+package stl2gltf
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"log"
+	"os"
+)
+
+func ConvertGLB(stl STL, outFile string) {
+	// buf
+	indexBuf := make([]byte, 0)
+	normalBuf := make([]byte, 0)
+	positionBuf := make([]byte, 0)
+
+	// padding each buffer part
+	padding := func(buf []byte) []byte {
+		for len(buf)%4 != 0 {
+			buf = append(buf, 0x00)
+		}
+		return buf
+	}
+
+	// positions to byte
+	for i := range stl.TriangleNum {
+		t := stl.Triangles[i]
+		positionBuf = append(positionBuf, t.Position...)
+	}
+	positionBuf = padding(positionBuf)
+
+	// normals to byte
+	for i := range stl.TriangleNum {
+		t := stl.Triangles[i]
+		// each position, write 3 times
+		normalBuf = append(normalBuf, t.Normal...)
+		normalBuf = append(normalBuf, t.Normal...)
+		normalBuf = append(normalBuf, t.Normal...)
+	}
+	normalBuf = padding(normalBuf)
+	// indices to byte
+	for i := range stl.TriangleNum * 3 {
+		buf := make([]byte, 4)
+		binary.LittleEndian.PutUint32(buf, uint32(i))
+		indexBuf = append(indexBuf, buf...)
+	}
+	indexBuf = padding(indexBuf)
+
+	log.Println("positions: ", len(positionBuf), " normals: ", len(normalBuf), " indices: ", len(indexBuf))
+
+	// concat
+	allData := make([]byte, 0)
+	allData = append(allData, indexBuf...)    // Indices: 0
+	allData = append(allData, normalBuf...)   // attributes["NORMAL"] = 1
+	allData = append(allData, positionBuf...) // attributes["POSITION"] = 2
+
+	// base := base64.StdEncoding.EncodeToString(allData)
+	attributes := make(map[string]int, 0)
+	attributes["NORMAL"] = 1
+	attributes["POSITION"] = 2
+
+	gltf := GLTF{
+		Asset:  Asset{Version: "2.0"},
+		Scenes: []Scene{{Nodes: []int{0}}},
+		Nodes:  []Node{{Mesh: 0}},
+		Meshes: []Mesh{{Primitives: []Primitive{{Attributes: attributes, Indices: 0, Mode: 4}}}},
+		// ByteLength not length after base64
+		Buffers: []Buffer{{ByteLength: len(allData)}},
+		BufferViews: []BufferView{
+			// index
+			{
+				Buffer:     0,
+				ByteOffset: 0,
+				ByteLength: len(indexBuf),
+				Target:     34963, // ELEMENT_ARRAY_BUFFER  float   indices
+			},
+			// normal
+			{
+				Buffer:     0,
+				ByteOffset: len(indexBuf),
+				ByteLength: len(normalBuf),
+				Target:     34962, // ARRAY_BUFFER    int   vertex
+			},
+			// position
+			{
+				Buffer:     0,
+				ByteOffset: len(indexBuf) + len(normalBuf),
+				ByteLength: len(positionBuf),
+				Target:     34962, // ARRAY_BUFFER    int   vertex
+			},
+		},
+		Accessors: []Accessor{
+			{
+				BufferView:    0,
+				ByteOffset:    0,
+				ComponentType: 5125,                // uint ;      5124 int will loss model parts
+				Type:          "SCALAR",            // index
+				Count:         stl.TriangleNum * 3, // 1 index : 1 position
+			},
+			{
+				BufferView:    1,
+				ByteOffset:    0,
+				ComponentType: 5126, // float
+				Type:          "VEC3",
+				Count:         stl.TriangleNum * 3, // 1 normal : 1 position
+				Max:           []float32{1, 1, 1},  // or cal from stl data
+				Min:           []float32{-1, -1, -1},
+			},
+			{
+				BufferView:    2,
+				ByteOffset:    0,
+				ComponentType: 5126, // float
+				Type:          "VEC3",
+				Count:         len(positionBuf) / 12, // xyz = 4x3; or stl.TriangleNum * 3
+				Max:           stl.Max,               // cal from stl data
+				Min:           stl.Min,
+			},
+		},
+	}
+
+	// 生成glb
+	outBuf := make([]byte, 0)
+
+	jsonChunkBuf := make([]byte, 0)
+
+	jsonData, err := json.Marshal(gltf)
+	if err != nil {
+		log.Println("marshal error: ", err.Error())
+		return
+	}
+	jsonChunkBuf = binary.LittleEndian.AppendUint32(jsonChunkBuf, uint32(len(jsonData)))
+	jsonChunkBuf = binary.LittleEndian.AppendUint32(jsonChunkBuf, uint32(0x4E4F534A))
+	jsonChunkBuf = append(jsonChunkBuf, jsonData...)
+
+	binChunkBuf := make([]byte, 0)
+	binChunkBuf = binary.LittleEndian.AppendUint32(binChunkBuf, uint32(len(allData)))
+	binChunkBuf = binary.LittleEndian.AppendUint32(binChunkBuf, uint32(0x004E4942))
+	binChunkBuf = append(binChunkBuf, allData...)
+
+	outBuf = binary.LittleEndian.AppendUint32(outBuf, uint32(0x46546C67))
+	outBuf = binary.LittleEndian.AppendUint32(outBuf, uint32(2))
+	outBuf = binary.LittleEndian.AppendUint32(outBuf, uint32(12+len(jsonChunkBuf)+len(binChunkBuf)))
+
+	outBuf = append(outBuf, jsonChunkBuf...)
+	outBuf = append(outBuf, binChunkBuf...)
+
+	// output
+	os.Remove(outFile)
+	f, err := os.OpenFile(outFile, os.O_CREATE, os.ModePerm)
+	if err != nil {
+		log.Println("write file error: ", err.Error())
+		return
+	}
+	defer f.Close()
+	f.Write(outBuf)
+}

data.go

@@ -1,7 +1,5 @@
 package stl2gltf
 
-import "encoding/binary"
-
 // Triangle 50B
 type Triangle struct {
 	Normal    []byte // 4 * 3     12
@@ -11,7 +9,6 @@ type Triangle struct {
 	XYZ []float32
 }
 
-
 //
 //        header     num
 //   |----80B------|-4B-|-----triangle1--------|--------triangle2-------|-----------...