FileFormat.Drako

FileFormat.Drako was ported from Google Draco.

1. Installation

Add the following code in your pom.xml:

<dependency>
  <groupId>dev.fileformat</groupId>
  <artifactId>drako</artifactId>
  <version>1.4.2</version>
</dependency>

2. Example

Vector3[] controlPoints = new Vector3[] {
    new Vector3(-5F, 0F, 5.0f),
    new Vector3(5F, 0F, 5.0f),
    new Vector3(5F, 10F, 5.0f),
    new Vector3(-5F, 10F, 5.0f),
    new Vector3(-5F, 0F, -5.0f),
    new Vector3(5F, 0F, -5.0f),
    new Vector3(5F, 10F, -5.0f),
    new Vector3(-5F, 10F, -5.0f)
};
        
int[] indices = new int[]
{
        0,1,2, 0, 2, 3, // Front face (Z+)
        1,5,6, 1, 6, 2, // Right side (X+)
        5,4,7, 5, 7, 6, // Back face (Z-)
        4,0,3, 4, 3, 7, // Left side (X-)
        0,4,5, 0, 5, 1, // Bottom face (Y-)
        3,2,6, 3, 6, 7 // Top face (Y+)
};
        
DracoMesh mesh = new DracoMesh();
PointAttribute attrPos = PointAttribute.wrap(AttributeType.POSITION, controlPoints);
mesh.addAttribute(attrPos);
//add triangle indices
mesh.getIndices().addRange(indices);
//number of the control points, it's required for the encoder to produce correct result.
mesh.setNumPoints(8);
DracoEncodeOptions opt = new DracoEncodeOptions();
byte[] drcBytes = Draco.encode(mesh, opt);

Convert Draco to OBJ format:

byte[] cube = Files.readAllBytes(Paths.get("TestData/cube.drc"));
DracoMesh dm = (DracoMesh)Draco.decode(cube);
PointAttribute attrPos = dm.getNamedAttribute(AttributeType.POSITION);
FloatSpan points = attrPos.getBuffer().asSpan().asFloatSpan();
StringBuilder sb = new StringBuilder();
for (int i = 0; i < points.size(); i += 3)
{
    sb.append(String.format("v %f %f %f\n", points.get(i), points.get(i + 1), points.get(i + 2)));
}

int[] face = new int[3];
for (int i = 0; i < dm.getNumFaces(); i++)
{
    dm.readFace(i, face);
    int a = attrPos.mappedIndex(face[0]) + 1;
    int b = attrPos.mappedIndex(face[1]) + 1;
    int c = attrPos.mappedIndex(face[2]) + 1;
    sb.append(String.format("f %d %d %d\n", a, b, c));
}

Files.writeString(Paths.get("output.obj"), sb.toString());

License

FileFormat.Drako is available under Openize License.

Caution

FileFormat does not and cannot grant You a patent license for the utilization of Google Draco compression/decompression technologies.

OSS Notice

Sample files used for tests and located in the "TestsData" folder belong to Google Draco and are used according to Apache License 2.0

Coming updates

FileFormat.Drako will receive new features and regular updates to stay in sync with the latest versions of Google Draco. We appreciate your patience as we work on these improvements. Stay tuned for more updates soon.