Merge pull request #295 from CesiumGS/double-sided-material

New optional parameter `doubleSidedMaterial` to force materials to be rendered on both sides
CesiumGS · Oct 3, 2023 · a26858a · a26858a
2 parents dc2500a + 0d4facf
commit a26858a
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diff --git a/CHANGES.md b/CHANGES.md
@@ -1,5 +1,9 @@
 # Change Log
 
+### 3.2.0 - 2023-??-??
+
+- Added `doubleSidedMaterial` option to force materials to be rendered double sided. [#294](https://github.com/CesiumGS/obj2gltf/pull/294)
+
 ### 3.1.6 - 2023-02-10
 
 - Update npm module dependencies.

diff --git a/README.md b/README.md
@@ -114,6 +114,7 @@ As a convenience the PBR textures may be supplied directly to the command line.
 | `--input-up-axis`                       | Up axis of the obj.                                                                                                                                                                                                                                                                                                                                                                                                                                       | No                     |
 | `--output-up-axis`                      | Up axis of the converted glTF.                                                                                                                                                                                                                                                                                                                                                                                                                            | No                     |
 | `--triangle-winding-order-sanitization` | Apply triangle winding order sanitization.                                                                                                                                                                                                                                                                                                                                                                                                                | No                     |
+| `--doubleSidedMaterial`                 | Allow the material properties to be double-sided                                                                                                                                                                                                                                                                                                                                                                                                          | No, default `false`    |
 
 ## Build Instructions
 

diff --git a/bin/obj2gltf.js b/bin/obj2gltf.js
@@ -160,6 +160,11 @@ const argv = yargs
       type: "boolean",
       default: defaults.triangleWindingOrderSanitization,
     },
+    doubleSidedMaterial: {
+      describe: "Allow the material properties to be double-sided",
+      type: "boolean",
+      default: defaults.doubleSidedMaterial,
+    },
   })
   .parse(args);
 
@@ -216,6 +221,7 @@ const options = {
   inputUpAxis: argv.inputUpAxis,
   outputUpAxis: argv.outputUpAxis,
   triangleWindingOrderSanitization: argv.triangleWindingOrderSanitization,
+  doubleSidedMaterial: argv.doubleSidedMaterial,
 };
 
 console.time("Total");

diff --git a/lib/loadMtl.js b/lib/loadMtl.js
@@ -853,7 +853,7 @@ function createSpecularGlossinessMaterial(material, options) {
     transparent = transparent || diffuseTexture.transparent;
   }
 
-  const doubleSided = transparent;
+  const doubleSided = transparent || options.doubleSidedMaterial;
   const alphaMode = transparent ? "BLEND" : "OPAQUE";
 
   return {
@@ -934,7 +934,7 @@ function createMetallicRoughnessMaterial(material, options) {
     transparent = transparent || baseColorTexture.transparent;
   }
 
-  const doubleSided = transparent;
+  const doubleSided = transparent || options.doubleSidedMaterial;
   const alphaMode = transparent ? "BLEND" : "OPAQUE";
 
   return {

diff --git a/lib/obj2gltf.js b/lib/obj2gltf.js
@@ -40,6 +40,7 @@ module.exports = obj2gltf;
  * @param {Logger} [options.logger] A callback function for handling logged messages. Defaults to console.log.
  * @param {Writer} [options.writer] A callback function that writes files that are saved as separate resources.
  * @param {String} [options.outputDirectory] Output directory for writing separate resources when options.writer is not defined.
+ * @param {Boolean} [options.doubleSidedMaterial=false] Allows materials to be double sided.
  * @return {Promise} A promise that resolves to the glTF JSON or glb buffer.
  */
 function obj2gltf(objPath, options) {
@@ -54,6 +55,10 @@ function obj2gltf(objPath, options) {
     options.checkTransparency,
     defaults.checkTransparency
   );
+  options.doubleSidedMaterial = defaultValue(
+    options.doubleSidedMaterial,
+    defaults.doubleSidedMaterial
+  );
   options.secure = defaultValue(options.secure, defaults.secure);
   options.packOcclusion = defaultValue(
     options.packOcclusion,
@@ -179,6 +184,12 @@ obj2gltf.defaults = {
    * @default false
    */
   checkTransparency: false,
+  /**
+   * Gets and sets whether a material will be doubleSided or not
+   * @type Boolean
+   * @default false
+   */
+  doubleSidedMaterial: false,
   /**
    * Gets or sets whether the source model can reference paths outside of its directory.
    * @type Boolean

diff --git a/specs/lib/loadMtlSpec.js b/specs/lib/loadMtlSpec.js
@@ -406,6 +406,14 @@ describe("loadMtl", () => {
       expect(material.alphaMode).toBe("BLEND");
       expect(material.doubleSided).toBe(true);
     });
+
+    it("uses doubleSidedMaterial option", () => {
+      options.metallicRoughness = true;
+      options.doubleSidedMaterial = true;
+
+      const material = loadMtl._createMaterial(undefined, options);
+      expect(material.doubleSided).toBe(true);
+    });
   });
 
   describe("specularGlossiness", () => {
@@ -530,5 +538,13 @@ describe("loadMtl", () => {
       expect(material.alphaMode).toBe("BLEND");
       expect(material.doubleSided).toBe(true);
     });
+
+    it("uses doubleSidedMaterial option", () => {
+      options.specularGlossiness = true;
+      options.doubleSidedMaterial = true;
+
+      const material = loadMtl._createMaterial(undefined, options);
+      expect(material.doubleSided).toBe(true);
+    });
   });
 });