Writing fragment shaders

Fragments (or pixels) are parts of the image that can be potentially displayed on screen. They are created from geometry (drawn primitives) in a process called rasterization. They have specific screen space coordinates (x, y, and depth) but don't have any other data. We need to write a fragment shader to specify the color that needs to be displayed on screen. In the fragment shader, we can also select an attachment into which a given color should be written.

How to do it...

1. Create a text file. Select a name for the file, but use a frag extension for it (for example, shader.frag).
2. Insert #version 450 in the first line of the file.
3. Define a set of input variables (attributes) that are provided from the earlier pipeline stages. For each input variable:
   1. Define its location with a location layout qualifier and an index of the attribute:layout( location = <index> )
   2. Provide an in storage qualifier
   3. Specify the type of input variable (such as vec4, float, ivec3)
   4. Provide a...