diff --git a/src/core/renderers/webgl/managers/FilterManager.js b/src/core/renderers/webgl/managers/FilterManager.js
index 6d69090..cbf8323 100644
--- a/src/core/renderers/webgl/managers/FilterManager.js
+++ b/src/core/renderers/webgl/managers/FilterManager.js
@@ -202,7 +202,7 @@
     this.quad.draw();
 };
 
-// thia returns a matrix that will normalise map filter cords in the filter to screen space
+// this returns a matrix that will normalise map filter cords in the filter to screen space
 FilterManager.prototype.syncUniforms = function (shader, filter)
 {
     var uniformData = filter.uniformData;
@@ -225,6 +225,8 @@
         shader.uniforms.filterArea = filterArea;
     }
 
+    // use this to clamp displaced texture coords so they belong to filterArea
+    // see displacementFilter fragment shader for an example
     if(shader.uniforms.data.filterClamp)
     {
         currentState = this.filterData.stack[this.filterData.index];