From 9abe85d64f5716e4e14f51abd491fe460f48800f Mon Sep 17 00:00:00 2001
From: onnowhere <17817284+onnowhere@users.noreply.github.com>
Date: Mon, 5 Apr 2021 21:44:24 -0700
Subject: [PATCH] Add FOV function

---
 .shader_utils/vsh_util.glsl | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/.shader_utils/vsh_util.glsl b/.shader_utils/vsh_util.glsl
index b043550..d4c7d9a 100644
--- a/.shader_utils/vsh_util.glsl
+++ b/.shader_utils/vsh_util.glsl
@@ -6,6 +6,14 @@
 #define LIGHT0_DIRECTION vec3(0.2, 1.0, -0.7) // Default light 0 direction everywhere except in inventory
 #define LIGHT1_DIRECTION vec3(-0.2, 1.0, 0.7) // Default light 1 direction everywhere except in nether and inventory
 
+/*
+ * Returns the FOV in degrees
+ * Calculates using the fact that top/near = tan(theta / 2)
+ */
+float getFOV(mat4 ProjMat) {
+    return atan(1.0, ProjMat[1][1]) * 114.591559;
+}
+
 /*
  * Returns if rendering in a GUI
  * In the GUI, near is 1000 and far is 3000, so -(far+near)/(far-near) = -2.0