Nove repo opengl-learning

include/assimp/qnan.h

@@ -0,0 +1,165 @@
+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (assimp)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2019, assimp team
+
+
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the following
+conditions are met:
+
+* Redistributions of source code must retain the above
+  copyright notice, this list of conditions and the
+  following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the
+  following disclaimer in the documentation and/or other
+  materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+  contributors may be used to endorse or promote products
+  derived from this software without specific prior
+  written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+---------------------------------------------------------------------------
+*/
+
+/**  @file  qnan.h
+ *   @brief Some utilities for our dealings with qnans.
+ *
+ *   @note Some loaders use qnans to mark invalid values tempoarily, also
+ *     Assimp explicitly enforces undefined normals to be set to qnan.
+ *     qnan utilities are available in standard libraries (C99 for example)
+ *     but last time I checked compiler coverage was so bad that I decided
+ *     to reinvent the wheel.
+ */
+
+#ifndef AI_QNAN_H_INCLUDED
+#define AI_QNAN_H_INCLUDED
+
+#include <assimp/defs.h>
+#include <limits>
+#include <stdint.h>
+
+// ---------------------------------------------------------------------------
+/** Data structure to represent the bit pattern of a 32 Bit
+ *         IEEE 754 floating-point number. */
+union _IEEESingle
+{
+    float Float;
+    struct
+    {
+        uint32_t Frac : 23;
+        uint32_t Exp  : 8;
+        uint32_t Sign : 1;
+    } IEEE;
+};
+
+// ---------------------------------------------------------------------------
+/** Data structure to represent the bit pattern of a 64 Bit
+ *         IEEE 754 floating-point number. */
+union _IEEEDouble
+{
+    double Double;
+    struct
+    {
+        uint64_t Frac : 52;
+        uint64_t Exp  : 11;
+        uint64_t Sign : 1;
+    } IEEE;
+};
+
+// ---------------------------------------------------------------------------
+/** Check whether a given float is qNaN.
+ *  @param in Input value */
+AI_FORCE_INLINE bool is_qnan(float in)
+{
+    // the straightforward solution does not work:
+    //   return (in != in);
+    // compiler generates code like this
+    //   load <in> to <register-with-different-width>
+    //   compare <register-with-different-width> against <in>
+
+    // FIXME: Use <float> stuff instead? I think fpclassify needs C99
+    _IEEESingle temp;
+    memcpy(&temp, &in, sizeof(float));
+    return (temp.IEEE.Exp == (1u << 8)-1 &&
+        temp.IEEE.Frac);
+}
+
+// ---------------------------------------------------------------------------
+/** Check whether a given double is qNaN.
+ *  @param in Input value */
+AI_FORCE_INLINE bool is_qnan(double in)
+{
+    // the straightforward solution does not work:
+    //   return (in != in);
+    // compiler generates code like this
+    //   load <in> to <register-with-different-width>
+    //   compare <register-with-different-width> against <in>
+
+    // FIXME: Use <float> stuff instead? I think fpclassify needs C99
+    _IEEEDouble temp;
+    memcpy(&temp, &in, sizeof(in));
+    return (temp.IEEE.Exp == (1u << 11)-1 &&
+        temp.IEEE.Frac);
+}
+
+// ---------------------------------------------------------------------------
+/** @brief check whether a float is either NaN or (+/-) INF.
+ *
+ *  Denorms return false, they're treated like normal values.
+ *  @param in Input value */
+AI_FORCE_INLINE bool is_special_float(float in)
+{
+    _IEEESingle temp;
+    memcpy(&temp, &in, sizeof(float));
+    return (temp.IEEE.Exp == (1u << 8)-1);
+}
+
+// ---------------------------------------------------------------------------
+/** @brief check whether a double is either NaN or (+/-) INF.
+ *
+ *  Denorms return false, they're treated like normal values.
+ *  @param in Input value */
+AI_FORCE_INLINE bool is_special_float(double in)
+{
+   _IEEESingle temp;
+    memcpy(&temp, &in, sizeof(float));
+    return (temp.IEEE.Exp == (1u << 11)-1);
+}
+
+// ---------------------------------------------------------------------------
+/** Check whether a float is NOT qNaN.
+ *  @param in Input value */
+template<class TReal>
+AI_FORCE_INLINE bool is_not_qnan(TReal in)
+{
+    return !is_qnan(in);
+}
+
+// ---------------------------------------------------------------------------
+/** @brief Get a fresh qnan.  */
+AI_FORCE_INLINE ai_real get_qnan()
+{
+    return std::numeric_limits<ai_real>::quiet_NaN();
+}
+
+#endif // !! AI_QNAN_H_INCLUDED