This example shows how to use the ComputeCaster material caster to make a custom casting using a compute shader written by the user.

// Copyright (c) Microsoft Corporation. 
// Licensed under the MIT License. 

#include <string>
#include <stdlib.h>
#include <filesystem>
#include <future>
#include "SimplygonLoader.h"


Simplygon::spScene LoadScene(Simplygon::ISimplygon* sg, const char* path)
{
	// Create scene importer 
	Simplygon::spSceneImporter sgSceneImporter = sg->CreateSceneImporter();
	sgSceneImporter->SetImportFilePath(path);
	
	// Run scene importer. 
	auto importResult = sgSceneImporter->Run();
	if (Simplygon::Failed(importResult))
	{
		throw std::exception("Failed to load scene.");
	}
	Simplygon::spScene sgScene = sgSceneImporter->GetScene();
	return sgScene;
}

void SaveScene(Simplygon::ISimplygon* sg, Simplygon::spScene sgScene, const char* path)
{
	// Create scene exporter. 
	Simplygon::spSceneExporter sgSceneExporter = sg->CreateSceneExporter();
	std::string outputScenePath = std::string("output\\") + std::string("ComputeCasting") + std::string("_") + std::string(path);
	sgSceneExporter->SetExportFilePath(outputScenePath.c_str());
	sgSceneExporter->SetScene(sgScene);
	
	// Run scene exporter. 
	auto exportResult = sgSceneExporter->Run();
	if (Simplygon::Failed(exportResult))
	{
		throw std::exception("Failed to save scene.");
	}
}

void CheckLog(Simplygon::ISimplygon* sg)
{
	// Check if any errors occurred. 
	bool hasErrors = sg->ErrorOccurred();
	if (hasErrors)
	{
		Simplygon::spStringArray errors = sg->CreateStringArray();
		sg->GetErrorMessages(errors);
		auto errorCount = errors->GetItemCount();
		if (errorCount > 0)
		{
			printf("%s\n", "Errors:");
			for (auto errorIndex = 0U; errorIndex < errorCount; ++errorIndex)
			{
				Simplygon::spString errorString = errors->GetItem((int)errorIndex);
				printf("%s\n", errorString.c_str());
			}
			sg->ClearErrorMessages();
		}
	}
	else
	{
		printf("%s\n", "No errors.");
	}
	
	// Check if any warnings occurred. 
	bool hasWarnings = sg->WarningOccurred();
	if (hasWarnings)
	{
		Simplygon::spStringArray warnings = sg->CreateStringArray();
		sg->GetWarningMessages(warnings);
		auto warningCount = warnings->GetItemCount();
		if (warningCount > 0)
		{
			printf("%s\n", "Warnings:");
			for (auto warningIndex = 0U; warningIndex < warningCount; ++warningIndex)
			{
				Simplygon::spString warningString = warnings->GetItem((int)warningIndex);
				printf("%s\n", warningString.c_str());
			}
			sg->ClearWarningMessages();
		}
	}
	else
	{
		printf("%s\n", "No warnings.");
	}
	
	// Error out if Simplygon has errors. 
	if (hasErrors)
	{
		throw std::exception("Processing failed with an error");
	}
}

void SetupCastingCodeInMaterial(Simplygon::ISimplygon* sg, Simplygon::spMaterial sgMaterial)
{
	// Create an evaluation shader, and add to the material. 
	Simplygon::spMaterialEvaluationShader sgMaterialEvaluationShader = sg->CreateMaterialEvaluationShader();
	sgMaterial->SetMaterialEvaluationShader( sgMaterialEvaluationShader );
	Simplygon::spShaderEvaluationFunctionTable sgShaderEvaluationFunctionTable = sgMaterialEvaluationShader->GetShaderEvaluationFunctionTable();
	Simplygon::spMaterialEvaluationShaderAttributeTable sgMaterialEvaluationShaderAttributeTable = sgMaterialEvaluationShader->GetMaterialEvaluationShaderAttributeTable();
	
	// Create an evaluation function, for channel 'Diffuse', add to the shader. 
	Simplygon::spShaderEvaluationFunction sgShaderEvaluationFunction = sg->CreateShaderEvaluationFunction();
	sgShaderEvaluationFunction->SetName( "Diffuse" );
	sgShaderEvaluationFunction->SetChannel( "Diffuse" );
	sgShaderEvaluationFunction->SetEntryPoint( "Diffuse" );
	sgShaderEvaluationFunctionTable->AddShaderEvaluationFunction(sgShaderEvaluationFunction);
	
	// Set up a needed vertex attribute from the source geometry: 'TexCoords', to read from. 
	Simplygon::spMaterialEvaluationShaderAttribute sgMaterialEvaluationShaderAttribute = sg->CreateMaterialEvaluationShaderAttribute();
	sgMaterialEvaluationShaderAttribute->SetName( "TexCoord" );
	sgMaterialEvaluationShaderAttribute->SetFieldType( Simplygon::EGeometryDataFieldType::TexCoords );
	sgMaterialEvaluationShaderAttribute->SetFieldFormat( Simplygon::EAttributeFormat::F32vec2 );
	sgMaterialEvaluationShaderAttributeTable->AddAttribute(sgMaterialEvaluationShaderAttribute);
	
	// Set the shader code to run. This example shader code returns the texture coords as red and green 
	// channels. Use GLSL shader language. 
	const char *shaderCode = R"(
vec4 Diffuse()
{
	return vec4(TexCoord.x,TexCoord.y,0,1);
}
)";
	sgMaterialEvaluationShader->SetShaderCode(shaderCode);
	sgMaterialEvaluationShader->SetShaderLanguage(Simplygon::EShaderLanguage::GLSL);
}

void SetupCastingCodeInScene(Simplygon::ISimplygon* sg, Simplygon::spScene sgScene)
{
	// Get the material table from the scene 
	Simplygon::spMaterialTable sgMaterialTable = sgScene->GetMaterialTable();
	
	// Enumerate all materials, and assign a custom shader to the Diffuse channel 
	auto materialsCount = sgMaterialTable->GetMaterialsCount();
	for (auto materialIndex = 0U; materialIndex < materialsCount; ++materialIndex)
	{
		auto material = sgMaterialTable->GetMaterial((int)materialIndex);
		SetupCastingCodeInMaterial(sg, material);
	}
}

void ComputeCasting(Simplygon::ISimplygon* sg)
{
	// Load scene to process. 	
	printf("%s\n", "Load scene to process.");
	Simplygon::spScene sgScene = LoadScene(sg, "../../../Assets/SimplygonMan/SimplygonMan.obj");
	
	// Add additional scene setup for the casting. 
	SetupCastingCodeInScene(sg, sgScene);
	
	// Create the aggregation processor. 
	Simplygon::spAggregationProcessor sgAggregationProcessor = sg->CreateAggregationProcessor();
	sgAggregationProcessor->SetScene( sgScene );
	Simplygon::spAggregationSettings sgAggregationSettings = sgAggregationProcessor->GetAggregationSettings();
	Simplygon::spMappingImageSettings sgMappingImageSettings = sgAggregationProcessor->GetMappingImageSettings();
	
	// Merge all geometries into a single geometry. 
	sgAggregationSettings->SetMergeGeometries( true );
	
	// Generates a mapping image which is used after the aggregation to cast new materials to the new 
	// aggregated object. 
	sgMappingImageSettings->SetGenerateMappingImage( true );
	sgMappingImageSettings->SetApplyNewMaterialIds( true );
	sgMappingImageSettings->SetGenerateTangents( true );
	sgMappingImageSettings->SetUseFullRetexturing( true );
	Simplygon::spMappingImageOutputMaterialSettings sgOutputMaterialSettings = sgMappingImageSettings->GetOutputMaterialSettings(0);
	
	// Setting the size of the output material for the mapping image. This will be the output size of the 
	// textures when we do material casting in a later stage. 
	sgOutputMaterialSettings->SetTextureWidth( 2048 );
	sgOutputMaterialSettings->SetTextureHeight( 2048 );
	
	// Start the aggregation process. 	
	printf("%s\n", "Start the aggregation process.");
	sgAggregationProcessor->RunProcessing();
	
	// Setup and run the compute shader material casting as a custom output to the diffuse channel. 
	Simplygon::spComputeCaster sgDiffuseCaster = sg->CreateComputeCaster();
	sgDiffuseCaster->SetMappingImage( sgAggregationProcessor->GetMappingImage() );
	sgDiffuseCaster->SetSourceMaterials( sgScene->GetMaterialTable() );
	sgDiffuseCaster->SetSourceTextures( sgScene->GetTextureTable() );
	sgDiffuseCaster->SetOutputFilePath( "DiffuseTexture" );

	Simplygon::spComputeCasterSettings sgDiffuseCasterSettings = sgDiffuseCaster->GetComputeCasterSettings();
	sgDiffuseCasterSettings->SetMaterialChannel( "Diffuse" );
	sgDiffuseCasterSettings->SetOutputImageFileFormat( Simplygon::EImageOutputFormat::PNG );

	sgDiffuseCaster->RunProcessing();
	std::string diffuseTextureFilePath = sgDiffuseCaster->GetOutputFilePath().c_str();
	
	// Update scene with new casted texture. 
	Simplygon::spMaterialTable sgMaterialTable = sg->CreateMaterialTable();
	Simplygon::spTextureTable sgTextureTable = sg->CreateTextureTable();
	Simplygon::spMaterial sgMaterial = sg->CreateMaterial();
	Simplygon::spTexture sgDiffuseTexture = sg->CreateTexture();
	sgDiffuseTexture->SetName( "Diffuse" );
	sgDiffuseTexture->SetFilePath( diffuseTextureFilePath.c_str() );
	sgTextureTable->AddTexture( sgDiffuseTexture );

	Simplygon::spShadingTextureNode sgDiffuseTextureShadingNode = sg->CreateShadingTextureNode();
	sgDiffuseTextureShadingNode->SetTexCoordLevel( 0 );
	sgDiffuseTextureShadingNode->SetTextureName( "Diffuse" );

	sgMaterial->AddMaterialChannel( "Diffuse" );
	sgMaterial->SetShadingNetwork( "Diffuse", sgDiffuseTextureShadingNode );

	sgMaterialTable->AddMaterial( sgMaterial );

	sgScene->GetTextureTable()->Clear();
	sgScene->GetMaterialTable()->Clear();
	sgScene->GetTextureTable()->Copy(sgTextureTable);
	sgScene->GetMaterialTable()->Copy(sgMaterialTable);
	
	// Save processed scene. 	
	printf("%s\n", "Save processed scene.");
	SaveScene(sg, sgScene, "Output.fbx");
	
	// Check log for any warnings or errors. 	
	printf("%s\n", "Check log for any warnings or errors.");
	CheckLog(sg);
}

int main()
{
	Simplygon::ISimplygon* sg = NULL;
	Simplygon::EErrorCodes initval = Simplygon::Initialize( &sg );
	if( initval != Simplygon::EErrorCodes::NoError )
	{
		printf( "Failed to initialize Simplygon: ErrorCode(%d)", (int)initval );
		return int(initval);
	}

	ComputeCasting(sg);

	Simplygon::Deinitialize(sg);

	return 0;
}

// Copyright (c) Microsoft Corporation. 
// Licensed under the MIT License. 

using System;
using System.IO;
using System.Threading.Tasks;

public class Program
{
    static Simplygon.spScene LoadScene(Simplygon.ISimplygon sg, string path)
    {
        // Create scene importer 
        using Simplygon.spSceneImporter sgSceneImporter = sg.CreateSceneImporter();
        sgSceneImporter.SetImportFilePath(path);
        
        // Run scene importer. 
        var importResult = sgSceneImporter.Run();
        if (Simplygon.Simplygon.Failed(importResult))
        {
            throw new System.Exception("Failed to load scene.");
        }
        Simplygon.spScene sgScene = sgSceneImporter.GetScene();
        return sgScene;
    }

    static void SaveScene(Simplygon.ISimplygon sg, Simplygon.spScene sgScene, string path)
    {
        // Create scene exporter. 
        using Simplygon.spSceneExporter sgSceneExporter = sg.CreateSceneExporter();
        string outputScenePath = string.Join("", new string[] { "output\\", "ComputeCasting", "_", path });
        sgSceneExporter.SetExportFilePath(outputScenePath);
        sgSceneExporter.SetScene(sgScene);
        
        // Run scene exporter. 
        var exportResult = sgSceneExporter.Run();
        if (Simplygon.Simplygon.Failed(exportResult))
        {
            throw new System.Exception("Failed to save scene.");
        }
    }

    static void CheckLog(Simplygon.ISimplygon sg)
    {
        // Check if any errors occurred. 
        bool hasErrors = sg.ErrorOccurred();
        if (hasErrors)
        {
            Simplygon.spStringArray errors = sg.CreateStringArray();
            sg.GetErrorMessages(errors);
            var errorCount = errors.GetItemCount();
            if (errorCount > 0)
            {
                Console.WriteLine("Errors:");
                for (uint errorIndex = 0; errorIndex < errorCount; ++errorIndex)
                {
                    string errorString = errors.GetItem((int)errorIndex);
                    Console.WriteLine(errorString);
                }
                sg.ClearErrorMessages();
            }
        }
        else
        {
            Console.WriteLine("No errors.");
        }
        
        // Check if any warnings occurred. 
        bool hasWarnings = sg.WarningOccurred();
        if (hasWarnings)
        {
            Simplygon.spStringArray warnings = sg.CreateStringArray();
            sg.GetWarningMessages(warnings);
            var warningCount = warnings.GetItemCount();
            if (warningCount > 0)
            {
                Console.WriteLine("Warnings:");
                for (uint warningIndex = 0; warningIndex < warningCount; ++warningIndex)
                {
                    string warningString = warnings.GetItem((int)warningIndex);
                    Console.WriteLine(warningString);
                }
                sg.ClearWarningMessages();
            }
        }
        else
        {
            Console.WriteLine("No warnings.");
        }
        
        // Error out if Simplygon has errors. 
        if (hasErrors)
        {
            throw new System.Exception("Processing failed with an error");
        }
    }

    static void SetupCastingCodeInMaterial(Simplygon.ISimplygon sg, Simplygon.spMaterial sgMaterial)
    {
        // Create an evaluation shader, and add to the material. 
        using Simplygon.spMaterialEvaluationShader sgMaterialEvaluationShader = sg.CreateMaterialEvaluationShader();
        sgMaterial.SetMaterialEvaluationShader( sgMaterialEvaluationShader );
        using Simplygon.spShaderEvaluationFunctionTable sgShaderEvaluationFunctionTable = sgMaterialEvaluationShader.GetShaderEvaluationFunctionTable();
        using Simplygon.spMaterialEvaluationShaderAttributeTable sgMaterialEvaluationShaderAttributeTable = sgMaterialEvaluationShader.GetMaterialEvaluationShaderAttributeTable();
        
        // Create an evaluation function, for channel 'Diffuse', add to the shader. 
        using Simplygon.spShaderEvaluationFunction sgShaderEvaluationFunction = sg.CreateShaderEvaluationFunction();
        sgShaderEvaluationFunction.SetName( "Diffuse" );
        sgShaderEvaluationFunction.SetChannel( "Diffuse" );
        sgShaderEvaluationFunction.SetEntryPoint( "Diffuse" );
        sgShaderEvaluationFunctionTable.AddShaderEvaluationFunction(sgShaderEvaluationFunction);
        
        // Set up a needed vertex attribute from the source geometry: 'TexCoords', to read from. 
        using Simplygon.spMaterialEvaluationShaderAttribute sgMaterialEvaluationShaderAttribute = sg.CreateMaterialEvaluationShaderAttribute();
        sgMaterialEvaluationShaderAttribute.SetName( "TexCoord" );
        sgMaterialEvaluationShaderAttribute.SetFieldType( Simplygon.EGeometryDataFieldType.TexCoords );
        sgMaterialEvaluationShaderAttribute.SetFieldFormat( Simplygon.EAttributeFormat.F32vec2 );
        sgMaterialEvaluationShaderAttributeTable.AddAttribute(sgMaterialEvaluationShaderAttribute);
        
        // Set the shader code to run. This example shader code returns the texture coords as red and green 
        // channels. Use GLSL shader language. 
        string shaderCode = @"
vec4 Diffuse()
{
	return vec4(TexCoord.x,TexCoord.y,0,1);
}
";
        sgMaterialEvaluationShader.SetShaderCode(shaderCode);
        sgMaterialEvaluationShader.SetShaderLanguage(Simplygon.EShaderLanguage.GLSL);
    }

    static void SetupCastingCodeInScene(Simplygon.ISimplygon sg, Simplygon.spScene sgScene)
    {
        // Get the material table from the scene 
        using Simplygon.spMaterialTable sgMaterialTable = sgScene.GetMaterialTable();
        
        // Enumerate all materials, and assign a custom shader to the Diffuse channel 
        var materialsCount = sgMaterialTable.GetMaterialsCount();
        for (uint materialIndex = 0; materialIndex < materialsCount; ++materialIndex)
        {
            var material = sgMaterialTable.GetMaterial((int)materialIndex);
            SetupCastingCodeInMaterial(sg, material);
        }
    }

    static void ComputeCasting(Simplygon.ISimplygon sg)
    {
        // Load scene to process.         
        Console.WriteLine("Load scene to process.");
        Simplygon.spScene sgScene = LoadScene(sg, "../../../Assets/SimplygonMan/SimplygonMan.obj");
        
        // Add additional scene setup for the casting. 
        SetupCastingCodeInScene(sg, sgScene);
        
        // Create the aggregation processor. 
        using Simplygon.spAggregationProcessor sgAggregationProcessor = sg.CreateAggregationProcessor();
        sgAggregationProcessor.SetScene( sgScene );
        using Simplygon.spAggregationSettings sgAggregationSettings = sgAggregationProcessor.GetAggregationSettings();
        using Simplygon.spMappingImageSettings sgMappingImageSettings = sgAggregationProcessor.GetMappingImageSettings();
        
        // Merge all geometries into a single geometry. 
        sgAggregationSettings.SetMergeGeometries( true );
        
        // Generates a mapping image which is used after the aggregation to cast new materials to the new 
        // aggregated object. 
        sgMappingImageSettings.SetGenerateMappingImage( true );
        sgMappingImageSettings.SetApplyNewMaterialIds( true );
        sgMappingImageSettings.SetGenerateTangents( true );
        sgMappingImageSettings.SetUseFullRetexturing( true );
        using Simplygon.spMappingImageOutputMaterialSettings sgOutputMaterialSettings = sgMappingImageSettings.GetOutputMaterialSettings(0);
        
        // Setting the size of the output material for the mapping image. This will be the output size of the 
        // textures when we do material casting in a later stage. 
        sgOutputMaterialSettings.SetTextureWidth( 2048 );
        sgOutputMaterialSettings.SetTextureHeight( 2048 );
        
        // Start the aggregation process.         
        Console.WriteLine("Start the aggregation process.");
        sgAggregationProcessor.RunProcessing();
        
        // Setup and run the compute shader material casting as a custom output to the diffuse channel. 
        string diffuseTextureFilePath;
        using Simplygon.spComputeCaster sgDiffuseCaster = sg.CreateComputeCaster();
        sgDiffuseCaster.SetMappingImage( sgAggregationProcessor.GetMappingImage() );
        sgDiffuseCaster.SetSourceMaterials( sgScene.GetMaterialTable() );
        sgDiffuseCaster.SetSourceTextures( sgScene.GetTextureTable() );
        sgDiffuseCaster.SetOutputFilePath( "DiffuseTexture" );

        using Simplygon.spComputeCasterSettings sgDiffuseCasterSettings = sgDiffuseCaster.GetComputeCasterSettings();
        sgDiffuseCasterSettings.SetMaterialChannel( "Diffuse" );
        sgDiffuseCasterSettings.SetOutputImageFileFormat( Simplygon.EImageOutputFormat.PNG );

        sgDiffuseCaster.RunProcessing();
        diffuseTextureFilePath = sgDiffuseCaster.GetOutputFilePath();
        
        // Update scene with new casted texture. 
        using Simplygon.spMaterialTable sgMaterialTable = sg.CreateMaterialTable();
        using Simplygon.spTextureTable sgTextureTable = sg.CreateTextureTable();
        using Simplygon.spMaterial sgMaterial = sg.CreateMaterial();
        using Simplygon.spTexture sgDiffuseTexture = sg.CreateTexture();
        sgDiffuseTexture.SetName( "Diffuse" );
        sgDiffuseTexture.SetFilePath( diffuseTextureFilePath );
        sgTextureTable.AddTexture( sgDiffuseTexture );

        using Simplygon.spShadingTextureNode sgDiffuseTextureShadingNode = sg.CreateShadingTextureNode();
        sgDiffuseTextureShadingNode.SetTexCoordLevel( 0 );
        sgDiffuseTextureShadingNode.SetTextureName( "Diffuse" );

        sgMaterial.AddMaterialChannel( "Diffuse" );
        sgMaterial.SetShadingNetwork( "Diffuse", sgDiffuseTextureShadingNode );

        sgMaterialTable.AddMaterial( sgMaterial );

        sgScene.GetTextureTable().Clear();
        sgScene.GetMaterialTable().Clear();
        sgScene.GetTextureTable().Copy(sgTextureTable);
        sgScene.GetMaterialTable().Copy(sgMaterialTable);
        
        // Save processed scene.         
        Console.WriteLine("Save processed scene.");
        SaveScene(sg, sgScene, "Output.fbx");
        
        // Check log for any warnings or errors.         
        Console.WriteLine("Check log for any warnings or errors.");
        CheckLog(sg);
    }

    static int Main(string[] args)
    {
        using var sg = Simplygon.Loader.InitSimplygon(out var errorCode, out var errorMessage);
        if (errorCode != Simplygon.EErrorCodes.NoError)
        {
            Console.WriteLine( $"Failed to initialize Simplygon: ErrorCode({(int)errorCode}) {errorMessage}" );
            return (int)errorCode;
        }
        ComputeCasting(sg);

        return 0;
    }

}

# Copyright (c) Microsoft Corporation. 
# Licensed under the MIT License. 

import math
import os
import sys
import glob
import gc
import threading

from pathlib import Path
from simplygon10 import simplygon_loader
from simplygon10 import Simplygon


def LoadScene(sg: Simplygon.ISimplygon, path: str):
    # Create scene importer 
    sgSceneImporter = sg.CreateSceneImporter()
    sgSceneImporter.SetImportFilePath(path)
    
    # Run scene importer. 
    importResult = sgSceneImporter.Run()
    if Simplygon.Failed(importResult):
        raise Exception('Failed to load scene.')
    sgScene = sgSceneImporter.GetScene()
    return sgScene

def SaveScene(sg: Simplygon.ISimplygon, sgScene: Simplygon.spScene, path: str):
    # Create scene exporter. 
    sgSceneExporter = sg.CreateSceneExporter()
    outputScenePath = ''.join(['output\\', 'ComputeCasting', '_', path])
    sgSceneExporter.SetExportFilePath(outputScenePath)
    sgSceneExporter.SetScene(sgScene)
    
    # Run scene exporter. 
    exportResult = sgSceneExporter.Run()
    if Simplygon.Failed(exportResult):
        raise Exception('Failed to save scene.')

def CheckLog(sg: Simplygon.ISimplygon):
    # Check if any errors occurred. 
    hasErrors = sg.ErrorOccurred()
    if hasErrors:
        errors = sg.CreateStringArray()
        sg.GetErrorMessages(errors)
        errorCount = errors.GetItemCount()
        if errorCount > 0:
            print('Errors:')
            for errorIndex in range(errorCount):
                errorString = errors.GetItem(errorIndex)
                print(errorString)
            sg.ClearErrorMessages()
    else:
        print('No errors.')
    
    # Check if any warnings occurred. 
    hasWarnings = sg.WarningOccurred()
    if hasWarnings:
        warnings = sg.CreateStringArray()
        sg.GetWarningMessages(warnings)
        warningCount = warnings.GetItemCount()
        if warningCount > 0:
            print('Warnings:')
            for warningIndex in range(warningCount):
                warningString = warnings.GetItem(warningIndex)
                print(warningString)
            sg.ClearWarningMessages()
    else:
        print('No warnings.')
    
    # Error out if Simplygon has errors. 
    if hasErrors:
        raise Exception('Processing failed with an error')

def SetupCastingCodeInMaterial(sg: Simplygon.ISimplygon, sgMaterial: Simplygon.spMaterial):
    # Create an evaluation shader, and add to the material. 
    sgMaterialEvaluationShader = sg.CreateMaterialEvaluationShader()
    sgMaterial.SetMaterialEvaluationShader( sgMaterialEvaluationShader )
    sgShaderEvaluationFunctionTable = sgMaterialEvaluationShader.GetShaderEvaluationFunctionTable()
    sgMaterialEvaluationShaderAttributeTable = sgMaterialEvaluationShader.GetMaterialEvaluationShaderAttributeTable()
    
    # Create an evaluation function, for channel 'Diffuse', add to the shader. 
    sgShaderEvaluationFunction = sg.CreateShaderEvaluationFunction()
    sgShaderEvaluationFunction.SetName( "Diffuse" )
    sgShaderEvaluationFunction.SetChannel( "Diffuse" )
    sgShaderEvaluationFunction.SetEntryPoint( "Diffuse" )
    sgShaderEvaluationFunctionTable.AddShaderEvaluationFunction(sgShaderEvaluationFunction)
    
    # Set up a needed vertex attribute from the source geometry: 'TexCoords', to read from. 
    sgMaterialEvaluationShaderAttribute = sg.CreateMaterialEvaluationShaderAttribute()
    sgMaterialEvaluationShaderAttribute.SetName( "TexCoord" )
    sgMaterialEvaluationShaderAttribute.SetFieldType( Simplygon.EGeometryDataFieldType_TexCoords )
    sgMaterialEvaluationShaderAttribute.SetFieldFormat( Simplygon.EAttributeFormat_F32vec2 )
    sgMaterialEvaluationShaderAttributeTable.AddAttribute(sgMaterialEvaluationShaderAttribute)
    
    # Set the shader code to run. This example shader code returns the texture coords as red and green 
    # channels. Use GLSL shader language. 
    shaderCode = """
vec4 Diffuse()
{
	return vec4(TexCoord.x,TexCoord.y,0,1);
}
"""
    sgMaterialEvaluationShader.SetShaderCode(shaderCode)
    sgMaterialEvaluationShader.SetShaderLanguage(Simplygon.EShaderLanguage_GLSL)

def SetupCastingCodeInScene(sg: Simplygon.ISimplygon, sgScene: Simplygon.spScene):
    # Get the material table from the scene 
    sgMaterialTable = sgScene.GetMaterialTable()
    
    # Enumerate all materials, and assign a custom shader to the Diffuse channel 
    materialsCount = sgMaterialTable.GetMaterialsCount()
    for materialIndex in range(materialsCount):
        material = sgMaterialTable.GetMaterial(materialIndex)
        SetupCastingCodeInMaterial(sg, material)

def ComputeCasting(sg: Simplygon.ISimplygon):
    # Load scene to process.     
    print("Load scene to process.")
    sgScene = LoadScene(sg, '../../../Assets/SimplygonMan/SimplygonMan.obj')
    
    # Add additional scene setup for the casting. 
    SetupCastingCodeInScene(sg, sgScene)
    
    # Create the aggregation processor. 
    sgAggregationProcessor = sg.CreateAggregationProcessor()
    sgAggregationProcessor.SetScene( sgScene )
    sgAggregationSettings = sgAggregationProcessor.GetAggregationSettings()
    sgMappingImageSettings = sgAggregationProcessor.GetMappingImageSettings()
    
    # Merge all geometries into a single geometry. 
    sgAggregationSettings.SetMergeGeometries( True )
    
    # Generates a mapping image which is used after the aggregation to cast new materials to the new 
    # aggregated object. 
    sgMappingImageSettings.SetGenerateMappingImage( True )
    sgMappingImageSettings.SetApplyNewMaterialIds( True )
    sgMappingImageSettings.SetGenerateTangents( True )
    sgMappingImageSettings.SetUseFullRetexturing( True )
    sgOutputMaterialSettings = sgMappingImageSettings.GetOutputMaterialSettings(0)
    
    # Setting the size of the output material for the mapping image. This will be the output size of the 
    # textures when we do material casting in a later stage. 
    sgOutputMaterialSettings.SetTextureWidth( 2048 )
    sgOutputMaterialSettings.SetTextureHeight( 2048 )
    
    # Start the aggregation process.     
    print("Start the aggregation process.")
    sgAggregationProcessor.RunProcessing()
    
    # Setup and run the compute shader material casting as a custom output to the diffuse channel. 
    sgDiffuseCaster = sg.CreateComputeCaster()
    sgDiffuseCaster.SetMappingImage( sgAggregationProcessor.GetMappingImage() )
    sgDiffuseCaster.SetSourceMaterials( sgScene.GetMaterialTable() )
    sgDiffuseCaster.SetSourceTextures( sgScene.GetTextureTable() )
    sgDiffuseCaster.SetOutputFilePath( 'DiffuseTexture' )

    sgDiffuseCasterSettings = sgDiffuseCaster.GetComputeCasterSettings()
    sgDiffuseCasterSettings.SetMaterialChannel( 'Diffuse' )
    sgDiffuseCasterSettings.SetOutputImageFileFormat( Simplygon.EImageOutputFormat_PNG )

    sgDiffuseCaster.RunProcessing()
    diffuseTextureFilePath = sgDiffuseCaster.GetOutputFilePath()
    
    # Update scene with new casted texture. 
    sgMaterialTable = sg.CreateMaterialTable()
    sgTextureTable = sg.CreateTextureTable()
    sgMaterial = sg.CreateMaterial()
    sgDiffuseTexture = sg.CreateTexture()
    sgDiffuseTexture.SetName( 'Diffuse' )
    sgDiffuseTexture.SetFilePath( diffuseTextureFilePath )
    sgTextureTable.AddTexture( sgDiffuseTexture )

    sgDiffuseTextureShadingNode = sg.CreateShadingTextureNode()
    sgDiffuseTextureShadingNode.SetTexCoordLevel( 0 )
    sgDiffuseTextureShadingNode.SetTextureName( 'Diffuse' )

    sgMaterial.AddMaterialChannel( 'Diffuse' )
    sgMaterial.SetShadingNetwork( 'Diffuse', sgDiffuseTextureShadingNode )

    sgMaterialTable.AddMaterial( sgMaterial )

    sgScene.GetTextureTable().Clear()
    sgScene.GetMaterialTable().Clear()
    sgScene.GetTextureTable().Copy(sgTextureTable)
    sgScene.GetMaterialTable().Copy(sgMaterialTable)
    
    # Save processed scene.     
    print("Save processed scene.")
    SaveScene(sg, sgScene, 'Output.fbx')
    
    # Check log for any warnings or errors.     
    print("Check log for any warnings or errors.")
    CheckLog(sg)

if __name__ == '__main__':
        sg = simplygon_loader.init_simplygon()
        if sg is None:
            exit(Simplygon.GetLastInitializationError())

        ComputeCasting(sg)

        sg = None
        gc.collect()