What is the differenc between 'attribute' and 'in' using glsl?

glsl, opengl

Solution

`attribute` and `varying` are deprecated since glsl 1.3 and were removed in glsl 1.4:

Here the extract from the glsl 1.4 specs (1.2.6 Summary of Functionality differences from version 1.2):

The following is a summary of features deprecated in version 1.3:

- Use of the keywords attribute and varying (use in and out).

Problem

What is the difference between writing ``` in vec3 position; ``` or ``` attribute vec3 position; ``` in a glsl shader?

Original source