obj2gltf/lib/gltf.js

"use strict";
var fs = require('fs');
var fsExtra = require('fs-extra');
var path = require('path');
var async = require('async');
var zlib = require('zlib');
var util = require('./util');
var defined = util.defined;
var defaultValue = util.defaultValue;
var imageInfo = require('./image');
var WebGLConstants = require('./WebGLConstants');
var modelMaterialsCommon = require('./modelMaterialsCommon');

module.exports = createGltf;

function getImages(inputPath, outputPath, embed, materials, done) {
    var images = [];

    for (var name in materials) {
        if (materials.hasOwnProperty(name)) {
            var material = materials[name];
            if (defined(material.ambientColorMap) && (images.indexOf(material.ambientColorMap) === -1)) {
                images.push(material.ambientColorMap);
            }
            if (defined(material.diffuseColorMap) && (images.indexOf(material.diffuseColorMap) === -1)) {
                images.push(material.diffuseColorMap);
            }
            if (defined(material.emissionColorMap) && (images.indexOf(material.emissionColorMap) === -1)) {
                images.push(material.emissionColorMap);
            }
            if (defined(material.specularColorMap) && (images.indexOf(material.specularColorMap) === -1)) {
                images.push(material.specularColorMap);
            }
        }
    }

    var imagesInfo = {};
    async.each(images, function (image, callback) {
        var imagePath = image;
        if (!path.isAbsolute(imagePath)) {
            imagePath = path.join(inputPath, image);
        }
        var baseName = path.basename(image);
        var copyPath = path.join(outputPath, baseName);
        imageInfo(imagePath, function(info) {
            var uri;
            if (embed) {
                uri = 'data:application/octet-stream;base64,' + info.data.toString('base64');
            } else {
                uri = baseName;
            }

            imagesInfo[image] = {
                transparent : info.transparent,
                channels : info.channels,
                uri : uri
            };

            if (embed) {
                callback();
            } else if (path.relative(imagePath, copyPath) !== '') {
                fsExtra.copy(imagePath, copyPath, {clobber : true}, function (err) {
                    if (err) {
                        throw err;
                    }
                    callback();
                });
            }
        });
    }, function (err) {
        if (err) {
            throw err;
        }
        done(imagesInfo);
    });
}

function createGltf(data, modelName, inputPath, outputPath, binary, embed, technique, done) {
    var vertexCount = data.vertexCount;
    var vertexArray = data.vertexArray;
    var positionMin = data.positionMin;
    var positionMax = data.positionMax;
    var hasUVs = data.hasUVs;
    var materialGroups = data.materialGroups;
    var materials = data.materials;

    getImages(inputPath, outputPath, embed, materials, function(images) {
        var i, j, name;

        var sizeOfFloat32 = 4;
        var sizeOfUint32 = 4;
        var sizeOfUint16 = 2;

        var indexComponentType;
        var indexComponentSize;

        // Reserve the 65535 index for primitive restart
        if (vertexCount < 65535) {
            indexComponentType = WebGLConstants.UNSIGNED_SHORT;
            indexComponentSize = sizeOfUint16;
        } else {
            indexComponentType = WebGLConstants.UNSIGNED_INT;
            indexComponentSize = sizeOfUint32;
        }

        // Create primitives
        var primitives = [];
        var indexArrayLength = 0;
        var indexArray;
        var indexCount;
        for (name in materialGroups) {
            if (materialGroups.hasOwnProperty(name)) {
                indexArray = materialGroups[name];
                indexCount = indexArray.length;
                primitives.push({
                    indexArray : indexArray,
                    indexOffset : indexArrayLength,
                    indexCount : indexCount,
                    material : name
                });
                indexArrayLength += indexCount;
            }
        }

        // Create buffer to store vertex and index data
        var indexArrayByteLength = indexArrayLength * indexComponentSize;
        var vertexArrayLength = vertexArray.length; // In floats
        var vertexArrayByteLength = vertexArrayLength * sizeOfFloat32;
        var bufferByteLength = vertexArrayByteLength + indexArrayByteLength;
        var buffer = new Buffer(bufferByteLength);

        // Write vertex data
        var byteOffset = 0;
        for (i = 0; i < vertexArrayLength; ++i) {
            buffer.writeFloatLE(vertexArray[i], byteOffset);
            byteOffset += sizeOfFloat32;
        }

        // Write index data
        var primitivesLength = primitives.length;
        for (i = 0; i < primitivesLength; ++i) {
            indexArray = primitives[i].indexArray;
            indexCount = indexArray.length;
            for (j = 0; j < indexCount; ++j) {
                if (indexComponentSize === sizeOfUint16) {
                    buffer.writeUInt16LE(indexArray[j], byteOffset);
                } else {
                    buffer.writeUInt32LE(indexArray[j], byteOffset);
                }
                byteOffset += indexComponentSize;
            }
        }

        var positionByteOffset = 0;
        var normalByteOffset = sizeOfFloat32 * 3;
        var uvByteOffset = sizeOfFloat32 * 6;
        var vertexByteStride = hasUVs ? sizeOfFloat32 * 8 : sizeOfFloat32 * 6;

        var binaryRelPath = modelName + '.bin';
        var binaryPath = path.join(outputPath, binaryRelPath);
        var bufferId = 'buffer_' + modelName;
        var bufferViewVertexId = 'bufferView_vertex';
        var bufferViewIndexId = 'bufferView_index';
        var accessorPositionId = 'accessor_position';
        var accessorUVId = 'accessor_uv';
        var accessorNormalId = 'accessor_normal';
        var meshId = 'mesh_' + modelName;
        var sceneId = 'scene_' + modelName;
        var nodeId = 'node_' + modelName;
        var samplerId = 'sampler_0';

        function getAccessorIndexId(i) {
            return 'accessor_index_' + i;
        }

        function getMaterialId(material) {
            return 'material_' + material;
        }

        function getTextureId(image) {
            if (!defined(image)) {
                return undefined;
            }
            return 'texture_' + path.basename(image).substr(0, image.lastIndexOf('.'));
        }

        function getImageId(image) {
            return 'image_' + path.basename(image).substr(0, image.lastIndexOf('.'));
        }

        var gltf = {
            accessors : {},
            asset : {},
            buffers : {},
            bufferViews : {},
            extensionsUsed : ['KHR_materials_common'],
            images : {},
            materials : {},
            meshes : {},
            nodes : {},
            samplers : {},
            scene : sceneId,
            scenes : {},
            textures : {}
        };

        gltf.asset = {
            "generator": "OBJ2GLTF",
            "premultipliedAlpha": true,
            "profile": {
                "api": "WebGL",
                "version": "1.0"
            },
            "version": 1
        };

        gltf.scenes[sceneId] = {
            nodes : [nodeId]
        };

        gltf.nodes[nodeId] = {
            children : [],
            matrix : [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1],
            meshes : [meshId],
            name : modelName
        };

        gltf.samplers[samplerId] = {}; // Use default values

        var bufferUri;
        if (embed) {
            bufferUri = 'data:application/octet-stream;base64,' + buffer.toString('base64');
        } else {
            bufferUri = binaryRelPath;
        }

        gltf.buffers[bufferId] = {
            byteLength : bufferByteLength,
            type : 'arraybuffer',
            uri : bufferUri
        };

        gltf.bufferViews[bufferViewVertexId] = {
            buffer : bufferId,
            byteLength : vertexArrayByteLength,
            byteOffset : 0,
            target : WebGLConstants.ARRAY_BUFFER
        };
        gltf.bufferViews[bufferViewIndexId] = {
            buffer : bufferId,
            byteLength : indexArrayByteLength,
            byteOffset : vertexArrayByteLength,
            target : WebGLConstants.ELEMENT_ARRAY_BUFFER
        };

        for (i = 0; i < primitivesLength; ++i) {
            var primitive = primitives[i];
            gltf.accessors[getAccessorIndexId(i)] = {
                bufferView : bufferViewIndexId,
                byteOffset : primitive.indexOffset * indexComponentSize,
                byteStride : 0,
                componentType : indexComponentType,
                count : primitive.indexCount,
                type : 'SCALAR'
            };
        }

        gltf.accessors[accessorPositionId] = {
            bufferView : bufferViewVertexId,
            byteOffset : positionByteOffset,
            byteStride : vertexByteStride,
            componentType : WebGLConstants.FLOAT,
            count : vertexCount,
            min : positionMin,
            max : positionMax,
            type : 'VEC3'
        };

        gltf.accessors[accessorNormalId] = {
            bufferView : bufferViewVertexId,
            byteOffset : normalByteOffset,
            byteStride : vertexByteStride,
            componentType : WebGLConstants.FLOAT,
            count : vertexCount,
            type : 'VEC3'
        };

        if (hasUVs) {
            gltf.accessors[accessorUVId] = {
                bufferView : bufferViewVertexId,
                byteOffset : uvByteOffset,
                byteStride : vertexByteStride,
                componentType : WebGLConstants.FLOAT,
                count : vertexCount,
                type : 'VEC2'
            };
        }

        var gltfPrimitives = [];
        gltf.meshes[meshId] = {
            name : modelName,
            primitives : gltfPrimitives
        };

        var gltfAttributes = {};
        gltfAttributes.POSITION = accessorPositionId;
        gltfAttributes.NORMAL = accessorNormalId;
        if (hasUVs) {
            gltfAttributes.TEXCOORD_0 = accessorUVId;
        }

        for (i = 0; i < primitivesLength; ++i) {
            gltfPrimitives.push({
                attributes : gltfAttributes,
                indices : getAccessorIndexId(i),
                material : getMaterialId(primitives[i].material),
                mode : WebGLConstants.TRIANGLES
            });
        }

        for (name in images) {
            if (images.hasOwnProperty(name)) {
                var image = images[name];
                var imageId = getImageId(name);
                var textureId = getTextureId(name);
                var format;
                var channels = image.channels;
                switch (channels) {
                    case 1:
                        format = WebGLConstants.ALPHA;
                        break;
                    case 2:
                        format = WebGLConstants.LUMINANCE_ALPHA;
                        break;
                    case 3:
                        format = WebGLConstants.RGB;
                        break;
                    case 4:
                        format = WebGLConstants.RGBA;
                        break;
                }

                gltf.images[imageId] = {
                    uri : image.uri
                };
                gltf.textures[textureId] = {
                    format : format,
                    internalFormat : format,
                    sampler : samplerId,
                    source : imageId,
                    target : WebGLConstants.TEXTURE_2D,
                    type : WebGLConstants.UNSIGNED_BYTE
                };
            }
        }

        for (i = 0; i < primitivesLength; ++i) {
            var materialName = primitives[i].material;
            var material = materials[materialName];
            var materialId = getMaterialId(materialName);

            // Get shading technique
            var shadingTechnique = technique;
            var specularColor = defaultValue(material.specularColor, [0, 0, 0, 1]);
            var specularShininess = material.specularShininess;
            var hasSpecularColor = (specularColor[0] > 0) || (specularColor[1] > 0) || (specularColor[2] > 0);
            var hasSpecularColorMap = defined(material.specularColorMap);
            if (defined(shadingTechnique)) {
                if ((shadingTechnique === 'PHONG') || (shadingTechnique === 'BLINN')) {
                    if (!defined(specularShininess)) {
                        specularShininess = 10.0;
                    }
                    if (!hasSpecularColor) {
                        specularColor[0] = specularColor[1] = specularColor[2] = 0.5;
                    }
                }
            } else {
                shadingTechnique = 'BLINN';
                if (!hasSpecularColorMap && !hasSpecularColor) {
                    shadingTechnique = 'LAMBERT';
                }
            }

            var values = {
                ambient : defaultValue(defaultValue(getTextureId(material.ambientColorMap), material.ambientColor), [0, 0, 0, 1]),
                diffuse : defaultValue(defaultValue(getTextureId(material.diffuseColorMap), material.diffuseColor), [0, 0, 0, 1]),
                emission : defaultValue(defaultValue(getTextureId(material.emissionColorMap), material.emissionColor), [0, 0, 0, 1]),
                specular : defaultValue(getTextureId(material.specularColorMap), specularColor),
                shininess : defaultValue(specularShininess, 0.0),
                transparency : defaultValue(material.alpha, 1.0)
            };

            // If an image is transparent, set transparency to 0.99 to force alpha path
            var diffuseColorMap = material.diffuseColorMap;
            if (defined(diffuseColorMap) && images[diffuseColorMap].transparent) {
                values.transparency = 0.99 * (values.transparency || 1.0);
            }

            gltf.materials[materialId] = {
                name : materialName,
                extensions : {
                    KHR_materials_common: {
                        technique: shadingTechnique,
                        values: values
                    }
                }
            };
        }

        // Generate techniques, shaders, and programs
        gltf = modelMaterialsCommon(gltf);

        // Save .gltf file
        var gltfPath = path.join(outputPath, modelName) + '.gltf';
        var gltfString = JSON.stringify(gltf, null, 4);
        fs.writeFile(gltfPath, gltfString, function(error) {
            if (error) {
                throw error;
            }
            if (embed) {
                done();
            } else {
                // Save .bin file
                fs.writeFile(binaryPath, buffer, function(error) {
                    if (error) {
                        throw error;
                    }
                    done();
                });
            }
        });
    });
}