Implement STL Parsing

1 files changed, 66 insertions, 0 deletions

diff --git a/stl.go b/stl.go
new file mode 100644
index 0000000..ceee2b7
--- /dev/null
+++ b/stl.go
@@ -0,0 +1,66 @@
+// vim: shiftwidth=4 tabstop=4 noexpandtab
+
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"encoding/binary"
+	"math"
+)
+
+type BinaryStl struct {
+	header []byte
+	numberOfTriangles uint32
+	surface Surface
+}
+
+func ReadBinaryStlFile(filePath string) (BinaryStl, error) {
+
+	fileContent, err := ioutil.ReadFile(filePath)
+	if err != nil {
+		return BinaryStl{}, err
+	}
+
+	model := BinaryStl{}
+	model.surface = Surface{}
+
+	model.header = fileContent[0:80]
+	log.Printf("STL header: '%s'\n", string(model.header))
+
+	model.numberOfTriangles = binary.LittleEndian.Uint32(fileContent[80:84])
+	log.Printf("STL model has %d triangles\n", model.numberOfTriangles)
+
+	var i uint32
+	for i = 0; i < model.numberOfTriangles; i++ {  // for each expected triangle
+		start := 84 + i*50  // 50 bytes is length of one triangle
+		end := 84 + (i+1)*50
+		model.surface.triangles = append(model.surface.triangles,
+			ParseBinaryStlTriangle(fileContent[start:end]))
+	}
+
+	return model,nil
+}
+
+func ParseBinaryStlTriangle(data []byte) *Triangle {  // FIXME: This function should only accept 50 byte slices/arrays
+
+	triangle := new(Triangle)
+	triangle.a = new(Point)
+	triangle.b = new(Point)
+	triangle.c = new(Point)
+
+	triangle.a.x = math.Float32frombits(binary.LittleEndian.Uint32(data[12:16]))
+	triangle.a.y = math.Float32frombits(binary.LittleEndian.Uint32(data[16:20]))
+	triangle.a.z = math.Float32frombits(binary.LittleEndian.Uint32(data[20:24]))
+
+	triangle.b.x = math.Float32frombits(binary.LittleEndian.Uint32(data[24:28]))
+	triangle.b.y = math.Float32frombits(binary.LittleEndian.Uint32(data[28:32]))
+	triangle.b.z = math.Float32frombits(binary.LittleEndian.Uint32(data[32:36]))
+
+	triangle.c.x = math.Float32frombits(binary.LittleEndian.Uint32(data[36:40]))
+	triangle.c.y = math.Float32frombits(binary.LittleEndian.Uint32(data[40:44]))
+	triangle.c.z = math.Float32frombits(binary.LittleEndian.Uint32(data[44:48]))
+
+	return triangle
+}
+