shader does work at least...

assets/blur.vert

@@ -1,7 +1,14 @@
-precision mediump float;
+attribute vec4 a_position;
+attribute vec4 a_color;
+attribute vec2 a_texCoord0;
 
-attribute vec2 position;
+uniform mat4 u_projTrans;
+
+varying vec4 v_color;
+varying vec2 v_texCoords;
 
 void main() {
-  gl_Position = vec4(position, 1, 1);
+    v_color = a_color;
+    v_texCoords = a_texCoord0;
+    gl_Position = u_projTrans * a_position;
 }