obj-to-colored-triangles

utility to convert a textured 3d mesh [Wavefront .obj] into a list of colored triangles.

eg, this colors the mesh with per-face or per-vertex colors that approximate the original texture.

note:

this tool is for Node.js only, not browsers.

this tool does not support quads -- if your model contains quads, you must first triangulate it with a tool like assimp

assimp export "model.obj" "model_triangulated_optimized.obj" -tri -om

Installation

npm i obj-to-colored-triangles

Usage

var otct = require('obj-to-colored-triangles');
var TEX = './Ficus-Carica-Texture-8k.jpg'; //texture file
var OBJ = './Ficus-Carica.OBJ'; //obj file including UV coords etc
var smoothColors = false; //if true, uses average of vertex colors. if false, takes color at center of each triangle.

var res = otct.obj2ColoredTrianglesSync(TEX, OBJ, smoothColors)[0]; //multi-mesh OBJ's may contain more than 1 result 

//res = {
//    tris, //triangles, each one [[x,y,z],[x,y,z],[x,y,z]] 
//    cells, //indexed faces, each one [a,b,c]
//    positions, //vertices, each one [x,y,z]
//    cells_uvs, //uv coords, each one [x,y] 
//    cellFlatColors, //color per triangle, each one like [255,255,255]
//    cellVertsColors //color per triangle per vertex, each row like [[255,255,255],[255,255,255],[255,255,255]]
// }

var cellFlatColors = res.cellFlatColors; 
//var cellVertsColors = res.cellVertsColors; 

//get simple reduced JSON representation, rescaled to be contained in bounding box size 10:
var boundsMaxDimension = 10;
var jsonObj = otct.getJsonModel(res2, boundsMaxDimension)

//getJsonModel(coloredTrianglesResultObj, rescaleSize = 10, FLOAT_DIGITS=3, doIncludeFlatColors = true, doIncludeVertColors=false)
//returns {meshIndexed, flatColors?, vertColors?}
//where meshIndexed = {cells, positions}

//obj2ColoredTrianglesMtl(objFile, mtlFile)
//for models whose colours come exclusively from .mtl color diffuse per-face
// returns 
// {
//     cells,
//     positions,
//     tris,
//     cellFlatColors
// }

^ original mesh with texture

^ mesh built from colored triangles, smoothColors = false;

^ mesh built from colored triangles, smoothColors = true;

See Also

• image-to-triangles