physicallyBasedMaterialX.py

'''
@brief Class to load Physically Based Materials from the PhysicallyBased site.
and convert the materials to MaterialX format for given target shading models.
'''
 
import requests, json, os, inspect # type: ignore
import logging as lg 
from http import HTTPStatus
import MaterialX as mx # type: ignore
from typing import Optional
 
class PhysicallyBasedMaterialLoader:
    '''
    @brief Class to load Physically Based Materials from the PhysicallyBased site.
    The class can convert the materials to MaterialX format for given target shading models.
    '''
    def __init__(self, mx_module, mx_stdlib : Optional[mx.Document] = None):
        '''
        @brief Constructor for the PhysicallyBasedMaterialLoader class. 
        Will initialize shader mappings and load the MaterialX standard library
        if it is not passed in as an argument.
        @param mx_module The MaterialX module. Required.
        @param mx_stdlib The MaterialX standard library. Optional.        
        '''
        
        self.logger = lg.getLogger('PBMXLoader')
        lg.basicConfig(level=lg.INFO)
 
        
        self.materialsmaterialsmaterials : dict = {}
        
        self.materialNames : list[str]= []
        
        self.uri = 'https://api.physicallybased.info/materials'
        
        self.doc = None
        
        self.mxmx = mx_module
        
        self.stdlib = mx_stdlib
        
        self.MTLX_NODE_NAME_ATTRIBUTE = 'nodename'
        
        self.support_openpbr = False
 
        if not mx_module:
            self.logger.critical(f'> {self._getMethodName()}: MaterialX module not specified.')
            return
        
        # Check for OpenPBR support which is only available in 1.39 and above
        version_major, version_minor, version_patch = self.mxmx.getVersionIntegers()
        self.logger.debug(f'> MaterialX version: {version_major}.{version_minor}.{version_patch}')
        if (version_major >=1 and version_minor >= 39) or version_major > 1:
            self.logger.debug('> OpenPBR shading model supported')
            self.support_openpbr = True
 
        self.initializeInputRemapping()
 
        # Load the MaterialX standard library if not provided
        if not self.stdlib:
            self.stdlib = self.mxmx.createDocument()
            libFiles = self.mxmx.loadLibraries(mx.getDefaultDataLibraryFolders(), mx.getDefaultDataSearchPath(), self.stdlib)            
            self.logger.debug(f'> Loaded standard library: {libFiles}')
 
    def setDebugging(self, debug=True):
        '''
        @brief Set the debugging level for the logger.
        @param debug True to set the logger to debug level, otherwise False.
        @return None
        '''
        if debug:
            self.logger.setLevel(lg.DEBUG)
        else:
            self.logger.setLevel(lg.INFO)
 
    def getInputRemapping(self, shadingModel) -> dict:
        '''
        @brief Get the remapping keys for a given shading model.
        @param shadingModel The shading model to get the remapping keys for.
        @return A dictionary of remapping keys.
        '''
        if (shadingModel in self.remapMap):
            return self.remapMap[shadingModel]
 
        self.logger.warn(f'> No remapping keys found for shading model: {shadingModel}')
        return {}
 
    def initializeInputRemapping(self): 
        ''' 
        @brief Initialize remapping keys for different shading models.
        The currently supported shading models are:
        - standard_surface
        - open_pbr_surface
        - gltf_pbr
        @return None
        '''
        # Remap keys for Autodesk Standard Surface shading model. 
        standard_surface_remapKeys = {
            'color': 'base_color',
            'specularColor': 'specular_color',
            'roughness': 'specular_roughness',
            #'metalness': 'metalness',
            'ior': 'specular_IOR',
            #'transmission': 'transmission',
            'transmission_color': 'transmission_color',
            'thinFilmIor' : 'thin_film_IOR',
            'thinFilmThickness' : 'thin_film_thickness',            
            'transmissionDispersion' : 'transmission_dispersion',
        }
        # Remap keys for OpenPBR shading model.
        # Q: When to set geometry_thin_walled to true?
        openpbr_remapKeys = {
            'color': 'base_color',
            'specularColor': 'specular_color',
            'roughness': 'specular_roughness', # 'base_diffuse_roughness',
            'metalness': 'base_metalness',
            'ior': 'specular_ior',
            'transmission': 'transmission_weight',
            'transmission_color': 'transmission_color',
            'subsurfaceRadius': 'subsurface_radius',
            'thinFilmIor' : 'thin_film_ior',
            'thinFilmThickness' : 'thin_film_thickness',
            'transmissionDispersion' : 'transmission_dispersion_scale',
        }
        # Remap keys for Khronos glTF shading model.
        gltf_remapKeys = {
            'color': 'base_color',
            'specularColor': 'specular_color',
            'roughness': 'roughness',
            'metalness': 'metallic',
            'transmission_color': 'attenuation_color',
            #'ior': 'ior',
            #'transmission': 'transmission',
        }
 
        self.remapMap = {}
        self.remapMap['standard_surface'] = standard_surface_remapKeys; 
        self.remapMap['gltf_pbr'] = gltf_remapKeys; 
        if self.support_openpbr:
            self.remapMap['open_pbr_surface'] = openpbr_remapKeys; 
 
    def getJSON(self) -> dict:
        ''' Get the JSON object representing the Physically Based Materials '''
        return self.materialsmaterialsmaterials
    
    def getJSONMaterialNames(self) -> list:
        ''' 
        Get the list of material names from the JSON object 
        @return The list of material names
        '''
        return self.materialNames
    
    def getMaterialXDocument(self) -> mx.Document:
        ''' 
        Get the MaterialX document 
        @return The MaterialX document
        '''
        return self.doc    
 
    def loadMaterialsFromFile(self, fileName) -> dict:
        ''' 
        @brief Load the Physically Based Materials from a JSON file 
        @param fileName The filename to load the JSON file from
        @return The JSON object representing the Physically Based Materials
        '''
        self.materialsmaterialsmaterials.clear()
        self.materialNames.clear()
        if not os.path.exists(fileName):
            self.logger.error(f'> File does not exist: {fileName}')
            return {}
 
        with open(fileName, 'r') as json_file:
            self.materialsmaterialsmaterials = json.load(json_file)
            for mat in self.materialsmaterialsmaterials:
                self.materialNames.append(mat['name'])
 
        return self.materialsmaterialsmaterials
    
    def loadMaterialsFromString(self, matString) -> dict:
        ''' 
        @brief Load the Physically Based Materials from a JSON string 
        @param matString The JSON string to load the Physically Based Materials from
        @return The JSON object representing the Physically Based Materials
        '''
        self.materialsmaterialsmaterials.clear()
        self.materialNames.clear()
        self.materialsmaterialsmaterials = json.loads(matString)
        for mat in self.materialsmaterialsmaterials:
            self.materialNames.append(mat['name'])
 
        return self.materialsmaterialsmaterials
 
    def getMaterialsFromURL(self) -> dict:
        ''' 
        @brief Get the Physically Based Materials from the PhysicallyBased site 
        @return The JSON object representing the Physically Based Materials
        '''
 
        self.materialsmaterialsmaterials.clear()
        self.materialNames.clear()
        url = self.uri
        headers = {
            'Accept': 'application/json'
        }
 
        response = requests.get(url, headers=headers)
 
        if response.status_code == HTTPStatus.OK:
            self.materialsmaterialsmaterials = response.json()
            for mat in self.materialsmaterialsmaterials:
                self.materialNames.append(mat['name'])
 
        else:
            self.logger.error(f'> Status: {response.status_code}, {response.text}')
 
        return self.materialsmaterialsmaterials
    
    def printMaterials(self):
        '''
        @brief Print the materials to the console
        @return None
        '''
        for mat in self.materialsmaterialsmaterials:
            self.logger.info('Material name: ' + mat['name'])
            # Print out each key and value
            for key, value in mat.items():
                if (key != 'name' and value):
                    self.logger.info(f'>  - {key}: {value}')
 
    def writeJSONToFile(self, filename):
        '''
        @brief Write the materials to a JSON file
        @param filename The filename to write the JSON file to
        @return True if the file was written successfully, otherwise False
        '''
        if not self.materialsmaterialsmaterials:
            self.logger.warning('No materials to write')
            return False
 
        with open(filename, 'w') as json_file:
            json.dump(self.materialsmaterialsmaterials, json_file, indent=4)
            return True
        
        return False
 
    @staticmethod
    def skipLibraryElement(elem) -> bool:
        '''
        @brief Utility to skip library elements when iterating over elements in a document.
        @return True if the element is not in a library, otherwise False.
        '''
        return not elem.hasSourceUri()
 
    def _getMethodName(self):
        frame = inspect.currentframe().f_back
        method_name = frame.f_code.co_name
        return method_name
        #return inspect.currentframe().f_code.co_name
 
    def validateMaterialXDocument(self, doc):
        ''' 
        @brief Validate the MaterialX document 
        @param doc The MaterialX document to validate
        @return A tuple of (valid, errors) where valid is True if the document is valid, and errors is a list of errors if the document is invalid.
        '''
        if not self.mxmx:
            self.logger.critical(f'> {self._getMethodName()}: MaterialX module is required')        
            return False, '' 
        
        if not doc:
            self.logger.warning(f'> {self._getMethodName()}: MaterialX document is required')
            return False, ''
 
        valid, errors = doc.validate()
        return valid, errors
 
    def addComment(self, doc, commentString):
        '''
        @brief Add a comment to the MaterialX document
        @param doc The MaterialX document to add the comment to
        @param commentString The comment string to add
        @return None
        '''
        comment = doc.addChildOfCategory('comment')
        comment.setDocString(commentString)
 
    def convertToMaterialX(self, materialNames = [], shaderCategory='standard_surface',
                           remapKeys = {}, shaderPreFix ='') -> mx.Document:
        '''
        @brief Convert the Physically Based Materials to MaterialX format for a given target shading model.
        @param materialNames The list of material names to convert. If empty, all materials will be converted.
        @param shaderCategory The target shading model to convert to. Default is 'standard_surface'.
        @param remapKeys The remapping keys for the target shading model. If empty, the default remapping keys will be used.
        @param shaderPreFix The prefix to add to the shader name. Default is an empty string.
        @return The MaterialX document
        '''
        if not self.mxmx:
            self.logger.critical(f'> {self._getMethodName()}: MaterialX module is required')
            return None
        
        if not self.support_openpbr and shaderCategory == 'open_pbr_surface':
            self.logger.warning(f'> OpenPBR shading model not supported in MaterialX version {self.mx.getVersionString()}')
            return None
 
        if not self.materialsmaterialsmaterials:
            self.logger.info('> No materials to convert')
            return None            
        
        if len(remapKeys) == 0:
            remapKeys = self.getInputRemapping(shaderCategory)
            if len(remapKeys) == 0:
                self.logger.warning(f'> No remapping keys found for shading model: {shaderCategory}')
 
        # Create main document and import the library document
        self.doc = self.mxmx.createDocument()
        if not self.doc:
            return None
 
        self.doc.importLibrary(self.stdlib)
 
        # Add header comments
        self.addComment(self.doc, 'Physically Based Materials from https://api.physicallybased.info ')
        self.addComment(self.doc, '  Processsed via API and converted to MaterialX ')  
        self.addComment(self.doc, '  Target Shading Model: ' + shaderCategory)  
        self.addComment(self.doc, '  Utility Author: Bernard Kwok. kwokcb@gmail.com ')  
 
        # Add properties to the material
        for mat in self.materialsmaterialsmaterials:
            matName = mat['name']
 
            # Filter by material name(s)
            if len(materialNames) > 0 and matName not in materialNames:
                #self.logger.debug('Skip material: ' + matName)
                continue            
 
            if (len(shaderPreFix) > 0):
                matName = matName + '_' + shaderPreFix 
 
            shaderName = self.doc.createValidChildName(matName + '_SHD_PBM')
            self.addComment(self.doc, ' Generated shader: ' + shaderName + ' ')         
            shaderNode = self.doc.addNode(shaderCategory, shaderName, self.mxmx.SURFACE_SHADER_TYPE_STRING)
            docString = mat['description']            
            refString = mat['reference']
            if len(refString) > 0:
                if len(docString) > 0:
                    docString += '. '
                docString += 'Reference: ' + refString[0]
            if len(docString) > 0:
                shaderNode.setDocString(docString)
            #shaderNode.addInputsFromNodeDef()
            #shaderNode.setAttribute(self.mx.InterfaceElement.NODE_DEF_ATTRIBUTE, nodedefString)
 
            # Create a new material
            materialName = self.doc.createValidChildName(matName + '_MAT_PBM')
            self.addComment(self.doc, ' Generated material: ' + materialName + ' ')         
            materialNode = self.doc.addNode(self.mxmx.SURFACE_MATERIAL_NODE_STRING, materialName, self.mxmx.MATERIAL_TYPE_STRING)
            shaderInput = materialNode.addInput(self.mxmx.SURFACE_SHADER_TYPE_STRING, self.mxmx.SURFACE_SHADER_TYPE_STRING)
            shaderInput.setAttribute(self.MTLX_NODE_NAME_ATTRIBUTE, shaderNode.getName())
            
            # Keys to skip.
            skipKeys = ['name', "density", "category", "description", "sources", "tags", "reference"]
 
            metallness = None
            roughness = None
            color = None
            transmission = None
            for key, value in mat.items():
                
                if (key not in skipKeys):
                    if key == 'metalness':
                        metallness = value
                    if key == 'roughness':
                        roughness = value
                    if key == 'transmission':
                        transmission = value
                    if key == 'color':
                        color = value
 
                    if key in remapKeys:
                        key = remapKeys[key]
                    input = shaderNode.addInputFromNodeDef(key)
                    if input:
                        # Convert number vector to string
                        if isinstance(value, list):
                            value = ','.join([str(x) for x in value])                        
                        # Convert number to string:
                        elif isinstance(value, (int, float)):
                            value = str(value)
                        input.setValueString(value)
                    #else:
                    #    self.logger.debug('Skip unsupported key: ' + key)
 
            if (transmission != None) and (metallness != None) and (roughness != None) and (color != None):
                if (metallness == 0) and (roughness == 0):
                    if 'transmission_color' in remapKeys:
                        key = remapKeys['transmission_color']
                        input = shaderNode.addInputFromNodeDef(key)
                        if input:
                            self.logger.debug(f'Set transmission color {key}: {color}')
                            value = ','.join([str(x) for x in color])                        
                            input.setValueString(value)
 
        return self.doc
    
    def writeMaterialXToFile(self, filename):
        ''' 
        @brief Write the MaterialX document to disk 
        @param filename The filename to write the MaterialX document to
        @return None
        '''
        if not self.mxmx:
            self.logger.critical(f'> {self._getMethodName()}: MaterialX module is required')
            return
 
        writeOptions = self.mxmx.XmlWriteOptions()
        writeOptions.writeXIncludeEnable = False
        writeOptions.elementPredicate = self.skipLibraryElement        
        self.mxmx.writeToXmlFile(self.doc, filename, writeOptions)
 
    def convertToMaterialXString(self):
        ''' 
        @brief Convert the MaterialX document to a string 
        @return The MaterialX document as a string
        '''
        if not self.mxmx:
            self.logger.critical(f'> {self._getMethodName()}: MaterialX module is required')
            return
 
        writeOptions = self.mxmx.XmlWriteOptions()
        writeOptions.writeXIncludeEnable = False
        writeOptions.elementPredicate = self.skipLibraryElement        
        mtlx = self.mxmx.writeToXmlString(self.doc, writeOptions)
        return mtlx