From bd90620bdfc880b65f0d2cc6065d2fed0a97ba58 Mon Sep 17 00:00:00 2001
From: Shariq Shah <shariqshah@outlook.com>
Date: Sun, 5 May 2019 16:31:25 +1000
Subject: [PATCH] Fixed quat to yaw, pitch and roll functions and rotation arc
 not matching up to actual rotation

---
 src/common/linmath.c | 25 +++++++++++++++++--------
 todo.txt             |  7 ++++---
 2 files changed, 21 insertions(+), 11 deletions(-)

diff --git a/src/common/linmath.c b/src/common/linmath.c
index 47661f4..ad057df 100755
--- a/src/common/linmath.c
+++ b/src/common/linmath.c
@@ -802,23 +802,32 @@ void quat_get_right(vec3* res, const quat* q)
 float quat_get_pitch(const quat* q)
 {
 	float check = 2.0f * (-q->y * q->z + q->w * q->x);
-	if(check < -0.995f || check > 0.995f)
-		return 0.f;
+	if(check < -0.995f)
+		return -90.f;
+	else if(check > 0.995)
+		return 90.f;
 	else
-		return TO_DEGREES(atan2f(2.f * (q->x * q->z + q->w * q->y), 1.f - 2.f * (q->x * q->x + q->y * q->y)));
-		//return TO_DEGREES(atan2f(2.f * (q->y * q->z + q->w * q->x), q->w * q->w - q->x * q->x - q->y * q->y + q->z * q->z));
+		return TO_DEGREES(asinf(check));
 }
 
 float quat_get_yaw(const quat* q)
 {
-	float result = (float)asin(-2 * (q->x * q->z - q->w * q->y));
-	return TO_DEGREES(result);
+	float check = 2.0f * (-q->y * q->z + q->w * q->x);
+	if(check > 0.995f || check < -0.995f)
+		return 0.f;
+	else
+		return TO_DEGREES(atan2f(2.0f * (q->x * q->z + q->w * q->y), 1.0f - 2.0f * (q->x * q->x + q->y * q->y)));
 }
 
 float quat_get_roll(const quat* q)
 {
-	float result = atan2(2 * (q->x * q->y + q->w * q->z), q->w * q->w + q->x * q->x - q->y * q->y - q->z * q->z);
-	return TO_DEGREES(result);
+	float check = 2.0f * (-q->y * q->z + q->w * q->x);
+	if(check < -0.955f)
+		return TO_DEGREES(-atan2f(2.0f * (q->x * q->z - q->w * q->y), 1.0f - 2.0f * (q->y * q->y + q->z * q->z)));
+	else if(check > 0.995f)
+		return TO_DEGREES(atan2f(2.0f * (q->x * q->z - q->w * q->y), 1.0f - 2.0f * (q->y * q->y + q->z * q->z)));
+	else
+		return TO_DEGREES(atan2f(2.0f * (q->x * q->y + q->w * q->z), 1.0f - 2.0f * (q->x * q->x + q->z * q->z)));
 }
 
 void quat_mul_mat4(quat* res, quat* val, mat4* mat)
diff --git a/todo.txt b/todo.txt
index 4682c0a..d1ac7d3 100644
--- a/todo.txt
+++ b/todo.txt
@@ -98,9 +98,8 @@ Bugs:
 	- Investigate memory usage increase when window is minimized
 	- Fix hang on fullscreen toggle
 	- Fix axis lines not aligning with grid lines
-	- Fix rotation arc starting and ending degree calculations
-	- Fix broken spot light degree/radian conversions
-
+	- Fix arc angles resetting when rotating
+	
 Done:
 	* Input
 	* Shaders
@@ -285,4 +284,6 @@ Done:
 	* Highlight if we are about to select an entity or perform the tool action like translate when mouse is hovered and an entity can be selected at that location
 	* Display the projected position if we perform the action for example display what the new location would be right next to the tool mesh
 	* Tooltips for current action or hovered entity
+	* Fix broken spot light degree/radian conversions
+	* Fix rotation arc starting and ending degree calculations