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stl2gltf
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glb

This commit is contained in:
dengqn 2024-06-07 00:50:09 +08:00
parent 7acdc03776
commit d56044f05c
5 changed files with 177 additions and 21 deletions
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1
.gitignore vendored
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@ -1 +1,2 @@
*.gltf
*.glb

3
cmd/stl2gltf.go
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@ -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")
}

4
convert.go
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@ -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)
@ -115,7 +115,7 @@ func Convert(stl STL, outFile string) {
ByteOffset: 0,
ComponentType: 5126, // float
Type: "VEC3",
Count: len(positionBuf) / 12,// xyz = 4x3; or stl.TriangleNum * 3
Count: len(positionBuf) / 12, // xyz = 4x3; or stl.TriangleNum * 3
Max: stl.Max, // cal from stl data
Min: stl.Min,
},

155
convert_glb.go Normal file
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@ -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)
}

3
data.go
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@ -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-------|-----------...