add opengraph images

_includes/head.html

@@ -17,6 +17,10 @@
         {% for tag in page.tags %}
             <meta name="og:article:tag" contents="{{ tag }}">
         {% endfor %}
+        {% if page.image %}
+            <meta name="og:image" 
+                contents="{{site.url}}/images/{{page.path | split: '/' | last | split: '.' | first }}/{{page.image}}">
+        {% endif %}
     {% else %}
         <meta name="og:type" 
             contents="website">

_posts/2019-5-4-Photorealistic-Particles.md

@@ -1,5 +1,6 @@
 ---
 title: Making Realistic Particle Effects From Photos
+image: setup-small.jpg
 tags: KSP restock gamedev 
 ---
 While working on drills for ReStock I realized I needed some particle effects for when the drills are in use. I wanted the effect of small rocks being kicked up from the ground and falling back down, but my attempts at a texture for the rocks all ended up looking more like potatos.