tests/glean/codedid.h

   1 // BEGIN_COPYRIGHT -*- glean -*-
   2 //
   3 // Copyright (C) 2000  Allen Akin   All Rights Reserved.
   4 //
   5 // Permission is hereby granted, free of charge, to any person
   6 // obtaining a copy of this software and associated documentation
   7 // files (the "Software"), to deal in the Software without
   8 // restriction, including without limitation the rights to use,
   9 // copy, modify, merge, publish, distribute, sublicense, and/or
  10 // sell copies of the Software, and to permit persons to whom the
  11 // Software is furnished to do so, subject to the following
  12 // conditions:
  13 //
  14 // The above copyright notice and this permission notice shall be
  15 // included in all copies or substantial portions of the
  16 // Software.
  17 //
  18 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
  19 // KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  20 // WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  21 // PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL ALLEN AKIN BE
  22 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  23 // AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
  24 // OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  25 // DEALINGS IN THE SOFTWARE.
  26 //
  27 // END_COPYRIGHT
  28
  29
  30
  31 // codedid.h:  tool to map integer IDs into colors, and vice-versa
  32
  33 // A note on principles of operation:  The OpenGL spec normally allows
  34 // a reasonable amount of slop when converting user-specified colors
  35 // to a hardware-dependent representation in the framebuffer.  One
  36 // exception to this lenience is when lighting is disabled and the
  37 // color is specified as an unsigned byte, short, or int.  In this
  38 // case the conversion from user-supplied color to hardware-determined
  39 // color must be exact, up to the number of bits in the framebuffer or
  40 // in the value supplied by the user (whichever is smaller).  This is
  41 // intended to allow object identification numbers to be encoded as
  42 // colors, so that applications can implement object selection by
  43 // drawing objects and reading back the image to determine the object
  44 // ID of the closest visible object.  glean uses this property in a
  45 // number of cases, for example, where it needs to draw a large number
  46 // of primitives and verify that all of them were actually drawn.  See
  47 // the OpenGL spec, version 1.2.1, section 2.13.9 (page 55) for the
  48 // description of this convertibility requirement.
  49
  50 #ifndef __codedid_h__
  51 #define __codedid_h__
  52
  53 using namespace std;
  54
  55 #include <vector>
  56 #include "glwrap.h"
  57
  58 namespace GLEAN {
  59
  60 class Image;                            // forward reference
  61
  62 class RGBCodedID {
  63         int rBits, gBits, bBits;        // number of signif. bits in channels
  64         int nsRBits, nsGBits, nsBBits;  // non-significant bits in each
  65         int rMask, gMask, bMask;        // masks for significant bits in each
  66     public:
  67         RGBCodedID(int r, int g, int b);
  68         ~RGBCodedID();
  69
  70         // Return the maximum ID number that the caller can use:
  71         int maxID() const;
  72
  73         // Map an ID number to an RGB triple:
  74         void toRGB(int id, GLubyte& r, GLubyte& g, GLubyte& b) const;
  75
  76         // Map an RGB triple to the equivalent ID number:
  77         int toID(GLubyte r, GLubyte g, GLubyte b) const;
  78
  79         // Histogram an UNSIGNED_BYTE RGB image:
  80         void histogram(Image& img, vector<int>& hist) const;
  81
  82         // Are all of a range of IDs present in an RGB image?
  83         bool allPresent(Image& img, int first, int last) const;
  84
  85 }; // RGBCodedID
  86
  87 // XXX Might want an IndexCodedID class for use with color index drawing
  88 // surfaces, even though such a class would be trivial.
  89
  90 } // namespace GLEAN
  91
  92 #endif // __codedid_h__