Managing to get GBM working

assets/shaders/textured.frag

@@ -1,13 +1,25 @@
-#version 130
+#version 320 es
 
-in vec2 TexCoord;
+#ifdef GL_ES
+  in mediump vec2 TexCoord;
+  uniform mediump sampler2D u_Text;
+  out mediump vec4 FragColor;
+  
+  void main() {
+    mediump vec4 color = texture(u_Text, TexCoord);
+    if(color.a == 0.0) discard;
+    FragColor = color;
+  }
+#else
+  #version 330 core
 
-uniform sampler2D u_Text;
+  in vec2 TexCoord;
+  uniform sampler2D u_Text;
+  out vec4 FragColor;
 
-out vec4 FragColor;
-
-void main() {
-  vec4 color = texture(u_Text, TexCoord);
-  if(color.a  == 0) discard;
-  FragColor = color;
-}
+  void main() {
+    vec4 color = texture(u_Text, TexCoord);
+    if(color.a == 0.0) discard;
+    FragColor = color;
+  }
+#endif