Add GLTF writer doc.

doc/stages/readers.text.rst

@@ -70,7 +70,7 @@ filename
 .. include:: reader_opts.rst
 
 header
-  String to use as the file header.  All lines in the file as assumed to be
+  String to use as the file header.  All lines in the file are assumed to be
   records containing point data unless skipped with the `skip`_ option.
   [Default: None]
 

doc/stages/writers.gltf.rst

@@ -0,0 +1,63 @@
+.. _writers.gltf:
+
+writers.gltf
+============
+
+GLTF is a file format `specification`_ for 3D graphics data.
+If a mesh has been generated
+for a PDAL point view, the **GLTF Writer** will produce simple output in
+the GLTF format.  PDAL does not currently support many of the attributes
+that can be found in a GLTF file.
+
+.. _specification: https://www.khronos.org/gltf/
+
+.. embed::
+
+Example
+-------
+
+.. code-block:: json
+
+  [
+      "infile.las",
+      {
+          "type": "filters.poisson",
+          "depth": 12
+      },
+      {
+          "type":"writers.gltf",
+          "filename":"output.gltf",
+          "red": 0.8,
+          "metallic": 0.5
+      }
+  ]
+
+Options
+-------
+
+filename
+    Name of the GLTF file to be written. [Required]
+
+metallic
+    The metallic factor of the faces. [Default: 0]
+
+roughness
+    The roughness factor of the faces. [Default: 0]
+
+red
+    The red component of the color applied to the faces. [Default: 0]
+
+green
+    The green component of the color applied to the faces. [Default: 0]
+
+blue
+    The blue component of the color applied to the faces. [Default: 0]
+
+alpha
+    The alpha component to be applied to the faces. [Default: 1.0]
+
+double_sided
+    Whether the faces are colored on both sides, or just the side
+    visible from the initial observation point (positive normal vector).
+    [Default: false]
+

doc/stages/writers.rst

@@ -21,6 +21,7 @@ dimension type, while others only understand fixed dimension names.
    writers.e57
    writers.gdal
    writers.geowave
+   writers.gltf
    writers.las
    writers.matlab
    writers.nitf
@@ -50,6 +51,9 @@ dimension type, while others only understand fixed dimension names.
 :ref:`writers.geowave`
     Write point cloud data to Accumulo.
 
+:ref:`writers.gltf`
+    Write mesh data in GLTF format.  Point clouds without meshes cannot be
+    written.
 
 :ref:`writers.las`
     Write ASPRS LAS versions 1.0 - 1.4 formatted data. LAZ support is also

io/GltfWriter.cpp

@@ -76,7 +76,7 @@ std::string GltfWriter::getName() const { return s_info.name; }
 
 void GltfWriter::addArgs(ProgramArgs& args)
 {
-    args.add("filename", "Output gltf filename", m_filename);
+    args.add("filename", "Output gltf filename", m_filename).setPositional();
     args.add("metallic", "Metallic factor [0-1]", m_metallic);
     args.add("roughness", "Roughness factor [0-1]", m_roughness);
     args.add("red", "Red factor [0-1]", m_red);