begin cleanup from other project

lib/imgui_extra_math.h

@@ -0,0 +1,68 @@
+//------------------------------------------------------------------------------
+// VERSION 0.9.1
+//
+// LICENSE
+//   This software is dual-licensed to the public domain and under the following
+//   license: you are granted a perpetual, irrevocable license to copy, modify,
+//   publish, and distribute this file as you see fit.
+//
+// CREDITS
+//   Written by Michal Cichon
+//------------------------------------------------------------------------------
+#ifndef __IMGUI_EXTRA_MATH_H__
+#define __IMGUI_EXTRA_MATH_H__
+#pragma once
+
+//------------------------------------------------------------------------------
+#ifndef IMGUI_DEFINE_MATH_OPERATORS
+#define IMGUI_DEFINE_MATH_OPERATORS
+#endif
+#include "imgui.h"
+#include "imgui_internal.h"
+
+//------------------------------------------------------------------------------
+struct ImLine {
+  ImVec2 A, B;
+};
+
+//------------------------------------------------------------------------------
+#if IMGUI_VERSION_NUM < 19002
+inline bool operator==(const ImVec2 &lhs, const ImVec2 &rhs);
+inline bool operator!=(const ImVec2 &lhs, const ImVec2 &rhs);
+#endif
+inline ImVec2 operator*(const float lhs, const ImVec2 &rhs);
+#if IMGUI_VERSION_NUM < 18955
+inline ImVec2 operator-(const ImVec2 &lhs);
+#endif
+
+//------------------------------------------------------------------------------
+inline float ImLength(float v);
+inline float ImLength(const ImVec2 &v);
+inline float ImLengthSqr(float v);
+inline ImVec2 ImNormalized(const ImVec2 &v);
+
+//------------------------------------------------------------------------------
+inline bool ImRect_IsEmpty(const ImRect &rect);
+inline ImVec2 ImRect_ClosestPoint(const ImRect &rect, const ImVec2 &p,
+                                  bool snap_to_edge);
+inline ImVec2 ImRect_ClosestPoint(const ImRect &rect, const ImVec2 &p,
+                                  bool snap_to_edge, float radius);
+inline ImVec2 ImRect_ClosestPoint(const ImRect &rect, const ImRect &b);
+inline ImLine ImRect_ClosestLine(const ImRect &rect_a, const ImRect &rect_b);
+inline ImLine ImRect_ClosestLine(const ImRect &rect_a, const ImRect &rect_b,
+                                 float radius_a, float radius_b);
+
+//------------------------------------------------------------------------------
+namespace ImEasing {
+
+template <typename V, typename T> inline V EaseOutQuad(V b, V c, T t) {
+  return b - c * (t * (t - 2));
+}
+
+} // namespace ImEasing
+
+//------------------------------------------------------------------------------
+#include "imgui_extra_math.inl"
+
+//------------------------------------------------------------------------------
+#endif // __IMGUI_EXTRA_MATH_H__