Proposed fix for issue where non-webgl enabled engine instances encounter null reference when reading glTexture information. added additional null checking in engine before gl context is invoked, added error handling to invoking parameters, and backed out texture export in case of error when exporting.

serializers/src/glTF/2.0/glTFMaterialExporter.ts

@@ -1138,7 +1138,7 @@ export class _GLTFMaterialExporter {
         return this._finishMaterial(promises, glTFMaterial, babylonPBRMaterial, mimeType);
     }
 
-    private getPixelsFromTexture(babylonTexture: BaseTexture): Uint8Array | Float32Array {
+    private getPixelsFromTexture(babylonTexture: BaseTexture): Nullable<Uint8Array | Float32Array> {
         const pixels = babylonTexture.textureType === Constants.TEXTURETYPE_UNSIGNED_INT ? babylonTexture.readPixels() as Uint8Array : babylonTexture.readPixels() as Float32Array;
         return pixels;
     }
@@ -1170,6 +1170,11 @@ export class _GLTFMaterialExporter {
                 return this._textureMap[textureUid];
             }
             else {
+                const pixels = this.getPixelsFromTexture(babylonTexture);
+                if (!pixels) {
+                    return null;
+                }
+
                 const samplers = this._exporter._samplers;
                 const sampler = this._getGLTFTextureSampler(babylonTexture);
                 let samplerIndex: Nullable<number> = null;
@@ -1184,6 +1189,7 @@ export class _GLTFMaterialExporter {
                         break;
                     }
                 }
+
                 if (foundSamplerIndex == null) {
                     samplers.push(sampler);
                     samplerIndex = samplers.length - 1;
@@ -1191,7 +1197,6 @@ export class _GLTFMaterialExporter {
                 else {
                     samplerIndex = foundSamplerIndex;
                 }
-                const pixels = this.getPixelsFromTexture(babylonTexture);
                 const size = babylonTexture.getSize();
 
                 return this._createBase64FromCanvasAsync(pixels, size.width, size.height, mimeType).then((base64Data) => {

src/Engines/engine.ts

@@ -1779,6 +1779,9 @@ export class Engine extends ThinEngine {
     /** @hidden */
     public _readTexturePixels(texture: InternalTexture, width: number, height: number, faceIndex = -1, level = 0, buffer: Nullable<ArrayBufferView> = null): ArrayBufferView {
         let gl = this._gl;
+        if (!gl) {
+            throw new Error ("Engine does not have gl rendering context.");
+        }
         if (!this._dummyFramebuffer) {
             let dummy = gl.createFramebuffer();
 

src/Materials/Textures/baseTexture.ts

@@ -669,11 +669,15 @@ export class BaseTexture implements IAnimatable {
             height = Math.round(height);
         }
 
-        if (this._texture.isCube) {
-            return engine._readTexturePixels(this._texture, width, height, faceIndex, level, buffer);
-        }
+        try {
+            if (this._texture.isCube) {
+                return engine._readTexturePixels(this._texture, width, height, faceIndex, level, buffer);
+            }
 
-        return engine._readTexturePixels(this._texture, width, height, -1, level, buffer);
+            return engine._readTexturePixels(this._texture, width, height, -1, level, buffer);
+        } catch (e) {
+            return null;
+        }
     }
 
     /**