From 669777eb37eaffd6079ba06893b87ccf1a352183 Mon Sep 17 00:00:00 2001
From: Recep Aslantas <info@recp.me>
Date: Mon, 18 Jun 2018 17:55:25 +0300
Subject: [PATCH] additional utils

---
 docs/source/util.rst | 35 +++++++++++++++++++++++++++++++++++
 include/cglm/util.h  | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+)

diff --git a/docs/source/util.rst b/docs/source/util.rst
index f8dbac4..846934f 100644
--- a/docs/source/util.rst
+++ b/docs/source/util.rst
@@ -136,3 +136,38 @@ Functions documentation
 
     Returns:
        interpolated value
+
+.. c:function:: bool glm_eq(float a, float b)
+
+    check if two float equal with using EPSILON
+
+    Parameters:
+      | *[in]*  **a**   a
+      | *[in]*  **b**   b
+
+    Returns:
+       true if a and b equals
+
+.. c:function:: float glm_percent(float from, float to, float current)
+
+    percentage of current value between start and end value
+
+    Parameters:
+      | *[in]*  **from**   from value
+      | *[in]*  **to**     to value
+      | *[in]*  **current**   value between from and to values
+
+    Returns:
+       clamped normalized percent (0-100 in 0-1)
+
+.. c:function:: float glm_percentc(float from, float to, float current)
+
+    clamped percentage of current value between start and end value
+
+    Parameters:
+      | *[in]*  **from**      from value
+      | *[in]*  **to**        to value
+      | *[in]*  **current**   value between from and to values
+
+    Returns:
+       clamped normalized percent (0-100 in 0-1)
diff --git a/include/cglm/util.h b/include/cglm/util.h
index af7514c..7a7b004 100644
--- a/include/cglm/util.h
+++ b/include/cglm/util.h
@@ -19,6 +19,7 @@
 #define cglm_util_h
 
 #include "common.h"
+#include <stdbool.h>
 
 /*!
  * @brief get sign of 32 bit integer as +1, -1, 0
@@ -157,4 +158,44 @@ glm_lerp(float from, float to, float t) {
   return from + glm_clamp(t, 0.0f, 1.0f) * (to - from);
 }
 
+/*!
+ * @brief check if two float equal with using EPSILON
+ *
+ * @param[in]   a   a
+ * @param[in]   b   b
+ */
+CGLM_INLINE
+bool
+glm_eq(float a, float b) {
+  return fabsf(a - b) <= FLT_EPSILON;
+}
+
+/*!
+ * @brief percentage of current value between start and end value
+ *
+ * maybe fraction could be alternative name.
+ *
+ * @param[in]   from from value
+ * @param[in]   to   to value
+ * @param[in]   t    current value
+ */
+CGLM_INLINE
+float
+glm_percent(float from, float to, float current) {
+  return (current - from) / (to - from);
+}
+
+/*!
+ * @brief clamped percentage of current value between start and end value
+ *
+ * @param[in]   from from value
+ * @param[in]   to   to value
+ * @param[in]   t    current value
+ */
+CGLM_INLINE
+float
+glm_percentc(float from, float to, float current) {
+  return glm_clamp(glm_percent(from, to, current), 0.0f, 1.0f);
+}
+
 #endif /* cglm_util_h */