Internals: Added ImFloorSigned() + use our own ImFloorSigned() for stb_truetype, compared as matching output for variety of font data. (#2884)

imgui_draw.cpp

@@ -145,7 +145,7 @@ namespace IMGUI_STB_NAMESPACE
 #define STBTT_sqrt(x)       ImSqrt(x)
 #define STBTT_pow(x,y)      ImPow(x,y)
 #define STBTT_fabs(x)       ImFabs(x)
-#define STBTT_ifloor(x)     ((int)ImFloorStd(x))
+#define STBTT_ifloor(x)     ((int)ImFloorSigned(x))
 #define STBTT_iceil(x)      ((int)ImCeil(x))
 #define STBTT_STATIC
 #define STB_TRUETYPE_IMPLEMENTATION

imgui_internal.h

@@ -64,6 +64,7 @@ Index of this file:
 #pragma clang diagnostic ignored "-Wunknown-warning-option"         // warning: unknown warning group 'xxx'
 #endif
 #pragma clang diagnostic ignored "-Wunknown-pragmas"                // warning: unknown warning group 'xxx'
+#pragma clang diagnostic ignored "-Wfloat-equal"                    // warning: comparing floating point with == or != is unsafe // storing and comparing against same constants ok, for ImFloorSigned()
 #pragma clang diagnostic ignored "-Wunused-function"                // for stb_textedit.h
 #pragma clang diagnostic ignored "-Wmissing-prototypes"             // for stb_textedit.h
 #pragma clang diagnostic ignored "-Wold-style-cast"
@@ -364,7 +365,7 @@ IMGUI_API void*             ImFileLoadToMemory(const char* filename, const char*
 #define ImAcos(X)           acosf(X)
 #define ImAtan2(Y, X)       atan2f((Y), (X))
 #define ImAtof(STR)         atof(STR)
-#define ImFloorStd(X)       floorf(X)           // We already uses our own ImFloor() { return (float)(int)v } internally so the standard one wrapper is named differently (it's used by e.g. stb_truetype)
+//#define ImFloorStd(X)     floorf(X)           // We use our own, see ImFloor() and ImFloorSigned()
 #define ImCeil(X)           ceilf(X)
 static inline float  ImPow(float x, float y)    { return powf(x, y); }          // DragBehaviorT/SliderBehaviorT uses ImPow with either float/double and need the precision
 static inline double ImPow(double x, double y)  { return pow(x, y); }
@@ -396,6 +397,7 @@ static inline float  ImLengthSqr(const ImVec2& lhs)
 static inline float  ImLengthSqr(const ImVec4& lhs)                             { return (lhs.x * lhs.x) + (lhs.y * lhs.y) + (lhs.z * lhs.z) + (lhs.w * lhs.w); }
 static inline float  ImInvLength(const ImVec2& lhs, float fail_value)           { float d = (lhs.x * lhs.x) + (lhs.y * lhs.y); if (d > 0.0f) return 1.0f / ImSqrt(d); return fail_value; }
 static inline float  ImFloor(float f)                                           { return (float)(int)(f); }
+static inline float  ImFloorSigned(float f)                                     { return (float)((f >= 0 || (int)f == f) ? (int)f : (int)f - 1); } // Decent replacement for floorf()
 static inline ImVec2 ImFloor(const ImVec2& v)                                   { return ImVec2((float)(int)(v.x), (float)(int)(v.y)); }
 static inline int    ImModPositive(int a, int b)                                { return (a + b) % b; }
 static inline float  ImDot(const ImVec2& a, const ImVec2& b)                    { return a.x * b.x + a.y * b.y; }