Tweak screen-reading_shaders

Fix grammar and punctuation in screen-reading_shaders.

tutorials/shading/screen-reading_shaders.rst

@@ -6,22 +6,22 @@ Screen-reading shaders
 Introduction
 ~~~~~~~~~~~~
 
-Very often it is desired to make a shader that reads from the same
-screen it's writing to. 3D APIs such as OpenGL or DirectX make this very
+Very often, it is desired to make a shader that reads from the same
+screen to which it's writing. 3D APIs, such as OpenGL or DirectX, make this very
 difficult because of internal hardware limitations. GPUs are extremely
-parallel, so reading and writing causes all sort of cache and coherency
+parallel, so reading and writing causes all sorts of cache and coherency
 problems. As a result, not even the most modern hardware supports this
 properly.
 
 The workaround is to make a copy of the screen, or a part of the screen,
 to a back-buffer and then read from it while drawing. Godot provides a
-few tools that makes this process easy!
+few tools that make this process easy!
 
 SCREEN_TEXTURE built-in texture
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Godot :ref:`doc_shading_language` has a special texture, "SCREEN_TEXTURE" (and "DEPTH_TEXTURE" for depth, in case of 3D).
-It takes as parameter the UV of the screen and returns a vec3 RGB with the color. A
+Godot :ref:`doc_shading_language` has a special texture, "SCREEN_TEXTURE" (and "DEPTH_TEXTURE" for depth, in the case of 3D).
+It takes as argument the UV of the screen and returns a vec3 RGB with the color. A
 special built-in varying: SCREEN_UV can be used to obtain the UV for
 the current fragment. As a result, this simple 2D fragment shader:
 
@@ -42,7 +42,7 @@ of blur at no cost.
 SCREEN_TEXTURE example
 ~~~~~~~~~~~~~~~~~~~~~~
 
-SCREEN_TEXTURE can be used for a lot of things. There is a
+SCREEN_TEXTURE can be used for many things. There is a
 special demo for *Screen Space Shaders*, that you can download to see
 and learn. One example is a simple shader to adjust brightness, contrast
 and saturation:
@@ -87,7 +87,7 @@ source for SCREEN_TEXTURE as the first one below, so the first one
 In 3D, this is unavoidable because copying happens when opaque rendering
 completes.
 
-In 2D this can be corrected via the :ref:`BackBufferCopy <class_BackBufferCopy>`
+In 2D, this can be corrected via the :ref:`BackBufferCopy <class_BackBufferCopy>`
 node, which can be instantiated between both spheres. BackBufferCopy can work by
 either specifying a screen region or the whole screen:
 
@@ -105,9 +105,9 @@ Godot:
 
 -  If a node uses the SCREEN_TEXTURE, the entire screen is copied to the
    back buffer before drawing that node. This only happens the first
-   time, subsequent nodes do not trigger this.
+   time; subsequent nodes do not trigger this.
 -  If a BackBufferCopy node was processed before the situation in the
-   point above (even if SCREEN_TEXTURE was not used), this behavior
+   point above (even if SCREEN_TEXTURE was not used), the behavior
    described in the point above does not happen. In other words,
    automatic copying of the entire screen only happens if SCREEN_TEXTURE is
    used in a node for the first time and no BackBufferCopy node (not
@@ -124,7 +124,7 @@ DEPTH_TEXTURE
 ~~~~~~~~~~~~~
 
 For 3D Shaders, it's also possible to access the screen depth buffer. For this,
-the DEPTH_TEXTURE built-in is used. This texture is not linear, it must be
+the DEPTH_TEXTURE built-in is used. This texture is not linear; it must be
 converted via the inverse projection matrix.
 
 The following code retrieves the 3D position below the pixel being drawn: