SOLVED:
Thanks to Demi. Here is the final code:

// Render opaque objects
        [_scene render:renderer opaque:true];

        // First planar shadow pass (if needed)
        [self renderPlanarShadows:renderer];

        // Render transparent objects
        glColorMask(1, 1, 1, 0);
        if (_zSortingEnabled) {
            [_scene renderZSortedAlphaObjects:renderer viewMatrix:&amp;viewMatrix];

        } else {
            [_scene render:renderer opaque:true];
        }
        glColorMask(1, 1, 1, 1);


Mobile 3D engine renders alpha as full-object transparency
We get a strange error in our system.log that says the following:

2015-06-04T07:45:25+00:00 ERR (3): Recoverable Error: Argument 1 passed to Mage_Catalog_Helper_Image::init() must be an instance of Mage_Catalog_Model_Product, null given, called in /home/tablet/domains/fooss.nl/public_html/app/design/frontend/default/default/template/catalog/product/list.phtml on line 104 and defined  in /home/tablet/domains/fooss.nl/public_html/app/code/core/Mage/Catalog/Helper/Image.php on line 139


this is what showon on line 104 in list.phtml

&lt;div class="hovertriggerinnerimages"&gt;       
                    &lt;div id="gallerythumbs"&gt;
                        &lt;?php
                         $product = Mage::getModel('catalog/product')-&gt;load($_product-&gt;getId());
                         $helper = Mage::Helper('catalog/image');
                            $imgi = 0;
                            foreach ($product-&gt;getMediaGalleryImages() as $image) {
                                if($imgi &lt; 5) {
                                    echo '&lt;a data-id="' . $_product-&gt;getId() . '" data-url="' . $this-&gt;helper('catalog/image')-&gt;init($this-&gt;getProduct(), 'thumbnail', $image-&gt;getFile())-&gt;resize(157) . '" class="hoveroverimagethumb ' . $_product-&gt;getId() . '-' . $imgi . '" href="' . $_product-&gt;getProductUrl() . '" title="' . $this-&gt;stripTags($this-&gt;getImageLabel($_product, 'small_image'), null, true) .'"&gt;&lt;img width="48" height="48" src="' . $this-&gt;helper('catalog/image')-&gt;init($this-&gt;getProduct(), 'thumbnail', $image-&gt;getFile())-&gt;resize(157) . '"/&gt;&lt;/a&gt;';
                                }
                                $imgi++;
                            }
                        ?&gt;
                    &lt;/div&gt;


Does someone know how to fix this?
