.mtl files support for .obj files to render color in 3D custom geometry

src/webgl/loading.js

@@ -229,18 +229,16 @@ p5.prototype.loadModel = function(path,options) {
           const parsedMaterials=await getMaterials(lines);
 
           if(parsedMaterials && typeof parsedMaterials==='object'){
-            try {
-              parseObj(model, lines, parsedMaterials);
-            } catch (error) {
-              console.error(error.message);
-            }
+            parseObj(model, lines, parsedMaterials);
           }
         }catch (error) {
+          console.error(error.message);
           if (failureCallback) {
             failureCallback(error);
           } else {
             p5._friendlyError('Error during parsing: ' + error.message);
           }
+          return;
         }
         finally{
           if (normalize) {
@@ -351,9 +349,9 @@ function parseObj(model, lines, materials= {}) {
   // Map from source index → Map of material → destination index
   const usedVerts = {}; // Track colored vertices
   let currentMaterial = null;
-  let uniqueVertices = 0; // all unique vertices count
   const coloredVerts = new Set(); //unique vertices with color
   let hasColoredVertices = false;
+  let hasColorlessVertices = false;
   for (let line = 0; line < lines.length; ++line) {
     // Each line is a separate object (vertex, face, vertex normal, etc)
     // For each line, split it into tokens on whitespace. The first token
@@ -372,9 +370,6 @@ function parseObj(model, lines, materials= {}) {
           parseFloat(tokens[2]),
           parseFloat(tokens[3])
         );
-        if (tokens[0]==='v'){
-          uniqueVertices++;
-        }
         loadedVerts[tokens[0]].push(vertex);
       } else if (tokens[0] === 'vt') {
         // Check if this line describes a texture coordinate.
@@ -417,7 +412,6 @@ function parseObj(model, lines, materials= {}) {
 
               usedVerts[vertParts[0]][currentMaterial] = vertIndex;
               face.push(vertIndex);
-
               if (currentMaterial
                 && materials[currentMaterial]
                 && materials[currentMaterial].diffuseColor) {
@@ -439,15 +433,18 @@ function parseObj(model, lines, materials= {}) {
             if (currentMaterial
               && materials[currentMaterial]
               && materials[currentMaterial].diffuseColor) {
-              const materialDiffuseColor =
-              materials[currentMaterial].diffuseColor;
+              hasColoredVertices=true;
               //flag to track color or no color model
               hasColoredVertices = true;
+              const materialDiffuseColor =
+              materials[currentMaterial].diffuseColor;
               for (let i = 0; i < face.length; i++) {
                 model.vertexColors.push(materialDiffuseColor[0]);
                 model.vertexColors.push(materialDiffuseColor[1]);
                 model.vertexColors.push(materialDiffuseColor[2]);
               }
+            }else{
+              hasColorlessVertices=true;
             }
           }
         }
@@ -458,19 +455,11 @@ function parseObj(model, lines, materials= {}) {
   if (model.vertexNormals.length === 0) {
     model.computeNormals();
   }
-  if (hasColoredVertices) {
-  // Ensure every vertex added has a color
-    if (coloredVerts.size !== uniqueVertices) {
-      throw new Error('Not all vertices have a color.');
-    }
-  } else {
-  // If no vertices are supposed to have color, ensure coloredVerts is empty
-    if (coloredVerts.size > 0) {
-      throw new Error('Unexpected colored vertices found.');
-    }
+  if (hasColoredVertices === hasColorlessVertices) {
+    // If both are true or both are false, throw an error because the model is inconsistent
+    throw new Error('Model coloring is inconsistent. Either all vertices should have colors or none should.');
   }
 
-
   return model;
 }
 

test/unit/assets/eg1.mtl

@@ -0,0 +1,9 @@
+newmtl coloredMaterial
+Ns 96.078431
+Ka 1.000000 1.000000 1.000000
+Kd 1.000000 0.000000 0.000000 # Only this material has a diffuse color
+Ks 0.500000 0.500000 0.500000
+Ke 0.0 0.0 0.0
+Ni 1.000000
+d 1.000000
+illum 2

test/unit/assets/eg1.obj

@@ -0,0 +1,16 @@
+mtllib eg1.mtl
+
+v 0 0 0
+v 1 0 0
+v 1 1 0
+v 0 1 0
+v 0.5 0.5 1
+
+# Define faces without material
+f 1 2 5
+f 2 3 5
+
+# Apply material to subsequent faces
+usemtl coloredMaterial
+f 1 4 5
+f 4 1 5

test/unit/io/loadModel.js

@@ -3,7 +3,7 @@ suite('loadModel', function() {
   var validFile = 'unit/assets/teapot.obj';
   var validObjFileforMtl='unit/assets/octa-color.obj';
   var validSTLfile = 'unit/assets/ascii.stl';
-  // const missingMtltoObjFile= 'unit/assets/plant.obj';
+  var inconsistentColorObjFile = 'unit/assets/eg1.obj';
   var validSTLfileWithoutExtension = 'unit/assets/ascii';
 
   test('_friendlyFileLoadError is called', async function() {
@@ -100,7 +100,7 @@ suite('loadModel', function() {
     };
   });
 
-  test.only('loads OBJ file with associated MTL file correctly', async function(){
+  test('loads OBJ file with associated MTL file correctly', async function(){
     const model = await promisedSketch(function (sketch,resolve,reject){
       sketch.preload=function(){
         sketch.loadModel(validObjFileforMtl,resolve,reject);
@@ -134,21 +134,24 @@ suite('loadModel', function() {
     ];
     assert.deepEqual(model.vertexColors,expectedColors);
   });
-  // test('throws an error for missing MTL file specified in OBJ file', async function() {
-  //   try {
-  //     await promisedSketch(function (sketch, resolve, reject) {
-  //       sketch.preload = function () {
-  //         sketch.loadModel(missingMtltoObjFile, resolve, reject);
-  //       };
-  //     });
-  //     // If the promise resolves without throwing an error, fail the test
-  //     assert.fail('Expected an error for missing MTL file, but the promise resolved successfully');
-  //   } catch (error) {
-  //     // Check if the error message indicates a missing MTL file
-  //     console.log(error);
-  //     assert.include(error.message, 'MTL file not found', 'Unexpected error message');
-  //   }
-  // });
+  test('inconsistent vertex coloring throws error', async function() {
+    // Attempt to load the model and catch the error
+    let errorCaught = null;
+    try {
+      await promisedSketch(function(sketch, resolve, reject) {
+        sketch.preload = function() {
+          sketch.loadModel(inconsistentColorObjFile, resolve, reject);
+        };
+      });
+    } catch (error) {
+      errorCaught = error;
+    }
+
+    // Assert that an error was caught and that it has the expected message
+    assert.instanceOf(errorCaught, Error, 'No error thrown for inconsistent vertex coloring');
+    assert.equal(errorCaught.message, 'Model coloring is inconsistent. Either all vertices should have colors or none should.', 'Unexpected error message for inconsistent vertex coloring');
+  });
+
   test('returns an object with correct data', async function() {
     const model = await promisedSketch(function(sketch, resolve, reject) {
       var _model;