src/mesa/main/querymatrix.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2008 Tungsten Graphics, Inc., Cedar Park, Texas.
   4  * All Rights Reserved.
   5  *
   6  **************************************************************************/
   7
   8
   9 /**
  10  * Code to implement GL_OES_query_matrix.  See the spec at:
  11  * http://www.khronos.org/registry/gles/extensions/OES/OES_query_matrix.txt
  12  */
  13
  14
  15 #include <stdlib.h>
  16 #include <math.h>
  17 #include "glheader.h"
  18 #include "querymatrix.h"
  19 #include "main/get.h"
  20
  21
  22 /**
  23  * This is from the GL_OES_query_matrix extension specification:
  24  *
  25  *  GLbitfield glQueryMatrixxOES( GLfixed mantissa[16],
  26  *                                GLint   exponent[16] )
  27  *  mantissa[16] contains the contents of the current matrix in GLfixed
  28  *  format.  exponent[16] contains the unbiased exponents applied to the
  29  *  matrix components, so that the internal representation of component i
  30  *  is close to mantissa[i] * 2^exponent[i].  The function returns a status
  31  *  word which is zero if all the components are valid. If
  32  *  status & (1<<i) != 0, the component i is invalid (e.g., NaN, Inf).
  33  *  The implementations are not required to keep track of overflows.  In
  34  *  that case, the invalid bits are never set.
  35  */
  36
  37 #define INT_TO_FIXED(x) ((GLfixed) ((x) << 16))
  38 #define FLOAT_TO_FIXED(x) ((GLfixed) ((x) * 65536.0))
  39
  40 #if defined(_MSC_VER)
  41 /* Oddly, the fpclassify() function doesn't exist in such a form
  42  * on MSVC.  This is an implementation using slightly different
  43  * lower-level Windows functions.
  44  */
  45 #include <float.h>
  46
  47 enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
  48 fpclassify(double x)
  49 {
  50     switch(_fpclass(x)) {
  51         case _FPCLASS_SNAN: /* signaling NaN */
  52         case _FPCLASS_QNAN: /* quiet NaN */
  53             return FP_NAN;
  54         case _FPCLASS_NINF: /* negative infinity */
  55         case _FPCLASS_PINF: /* positive infinity */
  56             return FP_INFINITE;
  57         case _FPCLASS_NN:   /* negative normal */
  58         case _FPCLASS_PN:   /* positive normal */
  59             return FP_NORMAL;
  60         case _FPCLASS_ND:   /* negative denormalized */
  61         case _FPCLASS_PD:   /* positive denormalized */
  62             return FP_SUBNORMAL;
  63         case _FPCLASS_NZ:   /* negative zero */
  64         case _FPCLASS_PZ:   /* positive zero */
  65             return FP_ZERO;
  66         default:
  67             /* Should never get here; but if we do, this will guarantee
  68              * that the pattern is not treated like a number.
  69              */
  70             return FP_NAN;
  71     }
  72 }
  73
  74 #elif defined(__APPLE__) || defined(__CYGWIN__) || defined(__FreeBSD__) || \
  75      defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || \
  76      (defined(__sun) && defined(__C99FEATURES__)) || defined(__MINGW32__) || \
  77      (defined(__sun) && defined(__GNUC__)) || defined(ANDROID) || defined(__HAIKU__)
  78
  79 /* fpclassify is available. */
  80
  81 #elif !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600
  82
  83 enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
  84 fpclassify(double x)
  85 {
  86    /* XXX do something better someday */
  87    return FP_NORMAL;
  88 }
  89
  90 #endif
  91
  92 GLbitfield GLAPIENTRY _mesa_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16])
  93 {
  94     GLfloat matrix[16];
  95     GLint tmp;
  96     GLenum currentMode = GL_FALSE;
  97     GLenum desiredMatrix = GL_FALSE;
  98     /* The bitfield returns 1 for each component that is invalid (i.e.
  99      * NaN or Inf).  In case of error, everything is invalid.
 100      */
 101     GLbitfield rv;
 102     register unsigned int i;
 103     unsigned int bit;
 104
 105     /* This data structure defines the mapping between the current matrix
 106      * mode and the desired matrix identifier.
 107      */
 108     static struct {
 109         GLenum currentMode;
 110         GLenum desiredMatrix;
 111     } modes[] = {
 112         {GL_MODELVIEW, GL_MODELVIEW_MATRIX},
 113         {GL_PROJECTION, GL_PROJECTION_MATRIX},
 114         {GL_TEXTURE, GL_TEXTURE_MATRIX},
 115     };
 116
 117     /* Call Mesa to get the current matrix in floating-point form.  First,
 118      * we have to figure out what the current matrix mode is.
 119      */
 120     _mesa_GetIntegerv(GL_MATRIX_MODE, &tmp);
 121     currentMode = (GLenum) tmp;
 122
 123     /* The mode is either GL_FALSE, if for some reason we failed to query
 124      * the mode, or a given mode from the above table.  Search for the
 125      * returned mode to get the desired matrix; if we don't find it,
 126      * we can return immediately, as _mesa_GetInteger() will have
 127      * logged the necessary error already.
 128      */
 129     for (i = 0; i < sizeof(modes)/sizeof(modes[0]); i++) {
 130         if (modes[i].currentMode == currentMode) {
 131             desiredMatrix = modes[i].desiredMatrix;
 132             break;
 133         }
 134     }
 135     if (desiredMatrix == GL_FALSE) {
 136         /* Early error means all values are invalid. */
 137         return 0xffff;
 138     }
 139
 140     /* Now pull the matrix itself. */
 141     _mesa_GetFloatv(desiredMatrix, matrix);
 142
 143     rv = 0;
 144     for (i = 0, bit = 1; i < 16; i++, bit<<=1) {
 145         float normalizedFraction;
 146         int exp;
 147
 148         switch (fpclassify(matrix[i])) {
 149             /* A "subnormal" or denormalized number is too small to be
 150              * represented in normal format; but despite that it's a
 151              * valid floating point number.  FP_ZERO and FP_NORMAL
 152              * are both valid as well.  We should be fine treating
 153              * these three cases as legitimate floating-point numbers.
 154              */
 155             case FP_SUBNORMAL:
 156             case FP_NORMAL:
 157             case FP_ZERO:
 158                 normalizedFraction = (GLfloat)frexp(matrix[i], &exp);
 159                 mantissa[i] = FLOAT_TO_FIXED(normalizedFraction);
 160                 exponent[i] = (GLint) exp;
 161                 break;
 162
 163             /* If the entry is not-a-number or an infinity, then the
 164              * matrix component is invalid.  The invalid flag for
 165              * the component is already set; might as well set the
 166              * other return values to known values.  We'll set
 167              * distinct values so that a savvy end user could determine
 168              * whether the matrix component was a NaN or an infinity,
 169              * but this is more useful for debugging than anything else
 170              * since the standard doesn't specify any such magic
 171              * values to return.
 172              */
 173             case FP_NAN:
 174                 mantissa[i] = INT_TO_FIXED(0);
 175                 exponent[i] = (GLint) 0;
 176                 rv |= bit;
 177                 break;
 178
 179             case FP_INFINITE:
 180                 /* Return +/- 1 based on whether it's a positive or
 181                  * negative infinity.
 182                  */
 183                 if (matrix[i] > 0) {
 184                     mantissa[i] = INT_TO_FIXED(1);
 185                 }
 186                 else {
 187                     mantissa[i] = -INT_TO_FIXED(1);
 188                 }
 189                 exponent[i] = (GLint) 0;
 190                 rv |= bit;
 191                 break;
 192
 193             /* We should never get here; but here's a catching case
 194              * in case fpclassify() is returnings something unexpected.
 195              */
 196             default:
 197                 mantissa[i] = INT_TO_FIXED(2);
 198                 exponent[i] = (GLint) 0;
 199                 rv |= bit;
 200                 break;
 201         }
 202
 203     } /* for each component */
 204
 205     /* All done */
 206     return rv;
 207 }