From ffd3dd5b685be092d28100523b598223bccc809b Mon Sep 17 00:00:00 2001
From: MindSpunk <godbotherer4@gmail.com>
Date: Sat, 15 Dec 2018 14:36:49 +1100
Subject: [PATCH] More compile options docs

---
 nalgebra-glm/src/lib.rs | 68 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/nalgebra-glm/src/lib.rs b/nalgebra-glm/src/lib.rs
index 71ffc251..d0cf4330 100644
--- a/nalgebra-glm/src/lib.rs
+++ b/nalgebra-glm/src/lib.rs
@@ -91,6 +91,74 @@
        This must be used with care! This is actually the recommended method to convert between homogeneous transformations generated by `nalgebra-glm` and
        specific transformation types from **nalgebra** like `Isometry3`. Just be careful you know your conversions make sense.
 
+   ### Compile Features/Options
+   There are a few compile features that alters the default behaviour of some functions. The current set of compile options includes:
+   * opengl_projection
+   * vulkan_projection
+   * directx_projection
+   * projection_y_flip
+   * left_hand_default
+   * right_hand_default
+   * zero_to_one_clip_default
+   * negone_to_one_clip_default
+
+   The default is to compile with the `opengl_projection` feature enabled
+
+   #### opengl_projection
+   This is a "macro" feature that exists as an alias to `right_hand_default` and
+   `negone_to_one_clip_default`
+
+   #### vulkan_projection
+   This is a "macro" feature that exists as an alias to `right_hand_default`,
+   `zero_to_one_clip_default` and `projection_y_flip`
+
+   #### directx_projection
+   This is a "macro" feature that exists as an alias to `left_hand_default` and
+   `zero_to_one_clip_default`
+
+   #### projection_y_flip
+   Applies an implicit `mat[(1,1)] *= -1` to all projection matrices created through the
+   nalgebra-glm interface. This feature should be enabled when using Vulkan so the generated
+   matrices conform to Vulkan's NDC (normalized device coordinates).
+
+   #### left_hand_default / right_hand_default
+   These two options are used to change the default handedness of the coordinate system the library
+   will use. Depending on which option is set it would cause a function like `ortho` to switch
+   between using `ortho_rh` and `ortho_lh`.
+
+   DO NOT set both of these options at the same time. There is no guarantee that all functions will
+   follow the same convention if you were to do so
+
+   #### zero_to_one_clip_default / negone_to_one_clip_default
+   These options are used to change the default depth range for projection matrices generated by
+   the nalgebra-glm interface. Depending on which option is set functions like `ortho` will
+   statically switch between calling `ortho_zo` and `ortho_no`.
+
+   DO NOT set both of these options at the same time. There is no guarantee that all functions will
+   follow the same convention if you were to do so
+
+   #### Functions Affected
+
+   * [`perspective`](fn.perspective.html)
+   * [`perspective_no`](fn.perspective_no.html)
+   * [`perspective_zo`](fn.perspective_zo.html)
+   * [`perspective_rh`](fn.perspective_rh.html)
+   * [`perspective_lh`](fn.perspective_lh.html)
+   * [`perspective_fov`](fn.perspective_fov.html)
+   * [`perspective_fov_no`](fn.perspective_fov_no.html)
+   * [`perspective_fov_zo`](fn.perspective_fov_zo.html)
+   * [`perspective_fov_rh`](fn.perspective_fov_rh.html)
+   * [`perspective_fov_lh`](fn.perspective_fov_lh.html)
+   * [`ortho`](fn.ortho.html)
+   * [`ortho_no`](fn.ortho_no.html)
+   * [`ortho_zo`](fn.ortho_zo.html)
+   * [`ortho_rh`](fn.ortho_rh.html)
+   * [`ortho_lh`](fn.ortho_lh.html)
+   * [`project`](fn.project.html)
+   * [`unproject`](fn.unproject.html)
+   * [`look_at`](fn.look_at.html)
+   * [`quat_look_at`](fn.quat_look_at.html)
+
    ### Should I use nalgebra or nalgebra-glm?
    Well that depends on your tastes and your background. **nalgebra** is more powerful overall since it allows stronger typing,
    and goes much further than simple computer graphics math. However, has a bit of a learning curve for