Merge pull request #8096 from Drigax/fix_nullEngine_nullref_engine_getTexturePixels

Fix for null reference in texture export for non-webGL enabled engines.

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/Extensions/engine.readTexture.ts

@@ -11,6 +11,9 @@ declare module "../../Engines/thinEngine" {
 
 ThinEngine.prototype._readTexturePixels = function(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

@@ -678,11 +678,15 @@ 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;
+        }
     }
 
     /**