Add default quality settings for jpeg and webp

examples/jsm/exporters/GLTFExporter.js

@@ -1115,7 +1115,26 @@ class GLTFWriter {
 
 				} else {
 
-					toBlobPromise = canvas.convertToBlob( { type: mimeType } );
+					let quality;
+
+					// Blink's implementation of convertToBlob seems to default to a quality level of 100%
+					// Use the Blink default quality levels of toBlob instead so that file sizes are comparable.
+					if ( mimeType === 'image/jpeg' ) {
+
+						quality = 0.92;
+
+					} else if ( mimeType === 'image/webp' ) {
+
+						quality = 0.8;
+
+					}
+
+					toBlobPromise = canvas.convertToBlob( {
+
+						type: mimeType,
+						quality: quality
+
+					} );
 
 				}