/// Authors USD Texture and PrimvarReader shader nodes for the given exportable material.
///
/// Note that textureUris are stored as metadata and only the "Export Texture" is authored as a
/// true texture in the shading network. This is due to the fact that the actual material textures
/// are not currently exported with the USD file, but export textures are.
///
/// Returns the texture path if a texture node was created, otherwise null.
static string CreateAlphaTexture(USD.NET.Scene scene,
string shaderPath,
IExportableMaterial material)
{
// Currently, only export texture is previewed in USD.
// Create an input parameter to read the texture, e.g. inputs:_MainTex.
if (!material.HasExportTexture())
{
return(null);
}
string texFile = SanitizeIdentifier(material.DurableName)
+ System.IO.Path.GetExtension(material.GetExportTextureFilename());
// Establish paths in the USD scene.
string texturePath = GetTexturePath(material, "MainTex", shaderPath);
string primvarPath = GetPrimvarPath(material, "uv", texturePath);
// Create the texture Prim.
var texture = new ExportTextureSample();
// Connect the texture to the file on disk.
texture.file.defaultValue = new pxr.SdfAssetPath(texFile);
texture.st.SetConnectedPath(primvarPath, "outputs:result");
scene.Write(texturePath, texture);
if (scene.GetPrimAtPath(new pxr.SdfPath(primvarPath)) == null)
{
if (material.VertexLayout.texcoord0.size == 2)
{
var primvar = new PrimvarReader2fSample("uv");
scene.Write(primvarPath, primvar);
}
else if (material.VertexLayout.texcoord0.size == 3)
{
var primvar = new PrimvarReader3fSample("uv");
scene.Write(primvarPath, primvar);
}
else if (material.VertexLayout.texcoord0.size == 4)
{
var primvar = new PrimvarReader4fSample("uv");
scene.Write(primvarPath, primvar);
}
}
return(texturePath);
}
/// Authors a USD Xform prim at the given path with the given matrix transform.
static void CreateXform(USD.NET.Scene scene, string path, Matrix4x4?xform = null)
{
var sample = new XformSample();
if (xform.HasValue)
{
sample.transform = xform.Value;
}
else
{
sample.transform = Matrix4x4.identity;
}
scene.Write(path, sample);
}
/// Authors the root "Sketch" object to be exported, with sketch metadta.
static void AddSketchRoot(USD.NET.Scene scene, string path)
{
var sample = CreateSketchRoot();
// Setup time to author default values, at no time sample.
var oldTime = scene.Time;
scene.Time = null;
// Write the data.
scene.Write(path, sample);
// Restore the desired time.
scene.Time = oldTime;
}
// -------------------------------------------------------------------------------------------- //
// Export Logic
// -------------------------------------------------------------------------------------------- //
/// Exports either all brush strokes or the given selection to the specified file.
static public void ExportPayload(string outputFile)
{
// Would be nice to find a way to kick this off automatically.
// Redundant calls are ignored.
if (!InitUsd.Initialize())
{
return;
}
// Unity is left handed (DX), USD is right handed (GL)
var payload = ExportCollector.GetExportPayload(AxisConvention.kUsd);
var brushCatalog = BrushCatalog.m_Instance;
// The Scene object provids serialization methods arbitrary C# objects to USD.
USD.NET.Scene scene = USD.NET.Scene.Create(outputFile);
// The target time at which samples will be written.
//
// In this case, all data is being written to the "default" time, which means it can be
// overridden by animated values later.
scene.Time = null;
// Bracketing times to specify the valid animation range.
scene.StartTime = 1.0;
scene.EndTime = 1.0;
const string kGeomName = "/Geom";
const string kCurvesName = "/Curves";
string path = "";
AddSketchRoot(scene, GetSketchPath()); // Create: </Sketch>
CreateXform(scene, GetStrokesPath()); // Create: </Sketch/Strokes>
CreateXform(scene, GetModelsPath()); // Create: </Sketch/Models>
// Main export loop.
try
{
foreach (ExportUtils.GroupPayload group in payload.groups)
{
// Example: </Sketch/Strokes/Group_0>
path = GetGroupPath(group.id);
CreateXform(scene, path);
// Example: </Sketch/Strokes/Group_0/Geom>
CreateXform(scene, path + kGeomName);
// Example: </Sketch/Strokes/Group_0/Curves>
CreateXform(scene, path + kCurvesName);
int iBrushMeshPayload = -1;
foreach (var brushMeshPayload in group.brushMeshes)
{
++iBrushMeshPayload;
// Conditionally moves Normal into Texcoord1 so that the normal semantic is respected.
// This only has an effect when layout.bFbxExportNormalAsTexcoord1 == true.
// Note that this modifies the GeometryPool in place.
FbxUtils.ApplyFbxTexcoordHack(brushMeshPayload.geometry);
// Brushes are expected to be batched by type/GUID.
Guid brushGuid = brushMeshPayload.strokes[0].m_BrushGuid;
string brushName = "/" +
SanitizeIdentifier(brushCatalog.GetBrush(brushGuid).DurableName) + "_";
// Example: </Sketch/Strokes/Group_0/Geom/Marker_0>
string meshPath = path + kGeomName + brushName;
// Example: </Sketch/Strokes/Group_0/Curves/Marker_0>
string curvePath = path + kCurvesName + brushName;
var geomPool = brushMeshPayload.geometry;
var strokes = brushMeshPayload.strokes;
var mat44 = Matrix4x4.identity;
var meshPrimPath = new pxr.SdfPath(meshPath + iBrushMeshPayload.ToString());
var curvesPrimPath = new pxr.SdfPath(curvePath + iBrushMeshPayload.ToString());
//
// Geometry
//
BrushSample brushSample = GetBrushSample(geomPool, strokes, mat44);
// Write the BrushSample to the same point in the scenegraph at which it exists in Tilt
// Brush. Notice this method is Async, it is queued to a background thread to perform I/O
// which means it is not safe to read from the scene until WaitForWrites() is called.
scene.Write(meshPrimPath, brushSample);
//
// Stroke Curves
//
var curvesSample = GetCurvesSample(payload, strokes, Matrix4x4.identity);
scene.Write(curvesPrimPath, curvesSample);
//
// Materials
//
double?oldTime = scene.Time;
scene.Time = null;
string materialPath = CreateMaterialNetwork(
scene,
brushMeshPayload.exportableMaterial,
GetStrokesPath());
BindMaterial(scene, meshPrimPath.ToString(), materialPath);
BindMaterial(scene, curvesPrimPath.ToString(), materialPath);
scene.Time = oldTime;
}
}
//
// Models
//
var knownModels = new Dictionary <Model, string>();
int iModelMeshPayload = -1;
foreach (var modelMeshPayload in payload.modelMeshes)
{
++iModelMeshPayload;
var modelId = modelMeshPayload.modelId;
var modelNamePrefix = "/Model_"
+ SanitizeIdentifier(modelMeshPayload.model.GetExportName())
+ "_";
var modelName = modelNamePrefix + modelId;
var xf = modelMeshPayload.xform;
// Geometry pools may be repeated and should be turned into references.
var geomPool = modelMeshPayload.geometry;
var modelRootPath = new pxr.SdfPath(GetModelsPath() + modelName);
// Example: </Sketch/Models/Model_Andy_0>
CreateXform(scene, modelRootPath, xf);
// Example: </Sketch/Models/Model_Andy_0/Geom>
CreateXform(scene, modelRootPath + kGeomName);
string modelPathToReference;
if (knownModels.TryGetValue(modelMeshPayload.model, out modelPathToReference) &&
modelPathToReference != modelRootPath)
{
// Create an Xform, note that the world transform here will override the referenced model.
var meshXf = new MeshXformSample();
meshXf.transform = xf;
scene.Write(modelRootPath, meshXf);
// Add a USD reference to previously created model.
var prim = scene.Stage.GetPrimAtPath(modelRootPath);
prim.GetReferences().AddReference("", new pxr.SdfPath(modelPathToReference));
continue;
}
// Example: </Sketch/Models/Geom/Model_Andy_0/Mesh_0>
path = modelRootPath + kGeomName + "/Mesh_" + iModelMeshPayload.ToString();
var meshPrimPath = new pxr.SdfPath(path);
var meshSample = new MeshSample();
GetMeshSample(geomPool, Matrix4x4.identity, meshSample);
scene.Write(path, meshSample);
scene.Stage.GetPrimAtPath(new pxr.SdfPath(path)).SetInstanceable(true);
//
// Materials
//
// Author at default time.
double?oldTime = scene.Time;
scene.Time = null;
// Model materials must live under the model root, since we will reference the model.
string materialPath = CreateMaterialNetwork(
scene,
modelMeshPayload.exportableMaterial,
modelRootPath);
BindMaterial(scene, meshPrimPath.ToString(), materialPath);
// Continue authoring at the desired time index.
scene.Time = oldTime;
//
// Setup to be referenced.
//
if (!knownModels.ContainsKey(modelMeshPayload.model))
{
knownModels.Add(modelMeshPayload.model, modelRootPath);
}
}
}
catch
{
scene.Save();
scene.Close();
throw;
}
// Save will force a sync with all async reads and writes.
scene.Save();
scene.Close();
}
/// Set the material:binding relationship on the mesh/curve to target the given materialPath.
static void BindMaterial(USD.NET.Scene scene, string primPath, string materialPath)
{
scene.Write(primPath, new MaterialBindingSample(materialPath));
}
/// Authors a USD Material, Shader, parameters and connections between the two.
/// The USD shader structure consists of a Material, which is connected to a shader output. The
/// Shader consists of input parameters which are either connected to other shaders or in the case
/// of public parameters, back to the material which is the public interface for the shading
/// network.
///
/// This function creates a material, shader, inputs, outputs, zero or more textures, and for each
/// texture, a single primvar reader node to read the UV data from the geometric primitive.
static string CreateMaterialNetwork(USD.NET.Scene scene,
IExportableMaterial material,
string rootPath = null)
{
var matSample = new ExportMaterialSample();
// Used scene object paths.
string materialPath = GetMaterialPath(material, rootPath);
string shaderPath = GetShaderPath(material, materialPath);
string displayColorPrimvarReaderPath = GetPrimvarPath(material, "displayColor", shaderPath);
string displayOpacityPrimvarReaderPath = GetPrimvarPath(material, "displayOpacity", shaderPath);
// The material was already created.
if (scene.GetPrimAtPath(materialPath) != null)
{
return(materialPath);
}
// Ensure the root material path is defined in the scene.
scene.Stage.DefinePrim(new pxr.SdfPath(rootPath));
// Connect the materail surface to the output of the shader.
matSample.surface.SetConnectedPath(shaderPath, "outputs:result");
scene.Write(materialPath, matSample);
// Create the shader and conditionally connect the diffuse color to the MainTex output.
var shaderSample = GetShaderSample(material);
var texturePath = CreateAlphaTexture(scene, shaderPath, material);
if (texturePath != null)
{
// A texture was created, so connect the opacity input to the texture output.
shaderSample.opacity.SetConnectedPath(texturePath, "outputs:a");
}
else
{
// TODO: currently primvars:displayOpacity is not multiplied when an alpha texture is
// present. However, this only affects the USD preview. The correct solution
// requires a multiply node in the shader graph, but this does not yet exist.
scene.Write(displayOpacityPrimvarReaderPath, new PrimvarReader1fSample("displayOpacity"));
shaderSample.opacity.SetConnectedPath(displayOpacityPrimvarReaderPath, "outputs:result");
}
// Create a primvar reader to read primvars:displayColor.
scene.Write(displayColorPrimvarReaderPath, new PrimvarReader3fSample("displayColor"));
// Connect the diffuse color to the primvar reader.
shaderSample.diffuseColor.SetConnectedPath(displayColorPrimvarReaderPath, "outputs:result");
scene.Write(shaderPath, shaderSample);
//
// Everything below is ad-hoc data, which is written using the low level USD API.
// It consists of the Unity shader parameters and the non-exported texture URIs.
// Also note that scene.GetPrimAtPath will return null when the prim is InValid,
// so there is no need to call IsValid() on the resulting prim.
//
var shadeMaterial = new pxr.UsdShadeMaterial(scene.GetPrimAtPath(materialPath));
var shadeShader = new pxr.UsdShadeShader(scene.GetPrimAtPath(shaderPath));
if (material.SupportsDetailedMaterialInfo)
{
CreateShaderInputs(shadeShader, shadeMaterial, material.FloatParams);
CreateShaderInputs(shadeShader, shadeMaterial, material.ColorParams);
CreateShaderInputs(shadeShader, shadeMaterial, material.VectorParams);
}
CreateTextureUris(shadeShader.GetPrim(), material);
return(materialPath);
}