replace position by brightness in comment (#448)

Author: clems4ever

webgl/lessons/webgl-3d-perspective-correct-texturemapping.md

@@ -140,7 +140,7 @@ and setup that attribute at render time
   // Turn on the attribute
   gl.enableVertexAttribArray(brightnessAttributeLocation);
 
-  // Bind the position buffer.
+  // Bind the brightness buffer.
   gl.bindBuffer(gl.ARRAY_BUFFER, brightnessBuffer);
 
   // Tell the attribute how to get data out of brightnessBuffer (ARRAY_BUFFER)

webgl/webgl-clipspace-rectangles-with-varying-non-1-w-repeat.html

@@ -145,7 +145,7 @@
   // Turn on the attribute
   gl.enableVertexAttribArray(brightnessAttributeLocation);
 
-  // Bind the position buffer.
+  // Bind the brightness buffer.
   gl.bindBuffer(gl.ARRAY_BUFFER, brightnessBuffer);
 
   // Tell the attribute how to get data out of brightnessBuffer (ARRAY_BUFFER)

webgl/webgl-clipspace-rectangles-with-varying-non-1-w.html

@@ -145,7 +145,7 @@
   // Turn on the attribute
   gl.enableVertexAttribArray(brightnessAttributeLocation);
 
-  // Bind the position buffer.
+  // Bind the brightness buffer.
   gl.bindBuffer(gl.ARRAY_BUFFER, brightnessBuffer);
 
   // Tell the attribute how to get data out of brightnessBuffer (ARRAY_BUFFER)

webgl/webgl-clipspace-rectangles-with-varying.html

@@ -144,7 +144,7 @@
   // Turn on the attribute
   gl.enableVertexAttribArray(brightnessAttributeLocation);
 
-  // Bind the position buffer.
+  // Bind the brightness buffer.
   gl.bindBuffer(gl.ARRAY_BUFFER, brightnessBuffer);
 
   // Tell the attribute how to get data out of brightnessBuffer (ARRAY_BUFFER)