kc3-lang/angle/src/common/mathutil.cpp

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• Author : Geoff Lang
  Date : 2014-06-12 14:10:47
  Hash : 0b7eef7c
  Message : Removed common_includes.h reordered includes. Since we are not using precompiled headers anymore, remove common_includes.h so that fewer files are included in cpp files. Reordered includes to be in the following order: 1) Local ANGLE project headers, ordered by directory in descending depth 2) GL headers 3) STL headers This helps enforce the include-what-you-use principal by reducing the number of STL headers unexpectedly shared between files. This include order conflicts with some of the Google c++ style guide which states that STL includes should be first but this helps us catch more issues. Change-Id: I8f7785f4ad574e253dd3c7b4fb1e54d3ce3b99fc Reviewed-on: https://chromium-review.googlesource.com/214850 Reviewed-by: Jamie Madill <jmadill@chromium.org> Tested-by: Geoff Lang <geofflang@chromium.org>

• src/common/mathutil.cpp

• //
  // Copyright (c) 2013 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  // mathutil.cpp: Math and bit manipulation functions.
  
  #include "common/mathutil.h"
  
  #include <algorithm>
  #include <math.h>
  
  namespace gl
  {
  
  struct RGB9E5Data
  {
      unsigned int R : 9;
      unsigned int G : 9;
      unsigned int B : 9;
      unsigned int E : 5;
  };
  
  // B is the exponent bias (15)
  static const int g_sharedexp_bias = 15;
  
  // N is the number of mantissa bits per component (9)
  static const int g_sharedexp_mantissabits = 9;
  
  // Emax is the maximum allowed biased exponent value (31)
  static const int g_sharedexp_maxexponent = 31;
  
  static const float g_sharedexp_max = ((pow(2.0f, g_sharedexp_mantissabits) - 1) /
                                         pow(2.0f, g_sharedexp_mantissabits)) *
                                       pow(2.0f, g_sharedexp_maxexponent - g_sharedexp_bias);
  
  unsigned int convertRGBFloatsTo999E5(float red, float green, float blue)
  {
      const float red_c = std::max<float>(0, std::min(g_sharedexp_max, red));
      const float green_c = std::max<float>(0, std::min(g_sharedexp_max, green));
      const float blue_c = std::max<float>(0, std::min(g_sharedexp_max, blue));
  
      const float max_c = std::max<float>(std::max<float>(red_c, green_c), blue_c);
      const float exp_p = std::max<float>(-g_sharedexp_bias - 1, floor(log(max_c))) + 1 + g_sharedexp_bias;
      const int max_s = floor((max_c / (pow(2.0f, exp_p - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
      const int exp_s = (max_s < pow(2.0f, g_sharedexp_mantissabits)) ? exp_p : exp_p + 1;
  
      RGB9E5Data output;
      output.R = floor((red_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
      output.G = floor((green_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
      output.B = floor((blue_c / (pow(2.0f, exp_s - g_sharedexp_bias - g_sharedexp_mantissabits))) + 0.5f);
      output.E = exp_s;
  
      return *reinterpret_cast<unsigned int*>(&output);
  }
  
  void convert999E5toRGBFloats(unsigned int input, float *red, float *green, float *blue)
  {
      const RGB9E5Data *inputData = reinterpret_cast<const RGB9E5Data*>(&input);
  
      *red = inputData->R * pow(2.0f, (int)inputData->E - g_sharedexp_bias - g_sharedexp_mantissabits);
      *green = inputData->G * pow(2.0f, (int)inputData->E - g_sharedexp_bias - g_sharedexp_mantissabits);
      *blue = inputData->B * pow(2.0f, (int)inputData->E - g_sharedexp_bias - g_sharedexp_mantissabits);
  }
  
  }