src/mesa/main/querymatrix.c

   1 /**************************************************************************
   2  *
   3  * Copyright 2008 VMware, Inc.
   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 #if _MSC_VER < 1800  /* Not required on VS2013 and above. */
  42 /* Oddly, the fpclassify() function doesn't exist in such a form
  43  * on MSVC.  This is an implementation using slightly different
  44  * lower-level Windows functions.
  45  */
  46 #include <float.h>
  47
  48 enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
  49 fpclassify(double x)
  50 {
  51     switch(_fpclass(x)) {
  52         case _FPCLASS_SNAN: /* signaling NaN */
  53         case _FPCLASS_QNAN: /* quiet NaN */
  54             return FP_NAN;
  55         case _FPCLASS_NINF: /* negative infinity */
  56         case _FPCLASS_PINF: /* positive infinity */
  57             return FP_INFINITE;
  58         case _FPCLASS_NN:   /* negative normal */
  59         case _FPCLASS_PN:   /* positive normal */
  60             return FP_NORMAL;
  61         case _FPCLASS_ND:   /* negative denormalized */
  62         case _FPCLASS_PD:   /* positive denormalized */
  63             return FP_SUBNORMAL;
  64         case _FPCLASS_NZ:   /* negative zero */
  65         case _FPCLASS_PZ:   /* positive zero */
  66             return FP_ZERO;
  67         default:
  68             /* Should never get here; but if we do, this will guarantee
  69              * that the pattern is not treated like a number.
  70              */
  71             return FP_NAN;
  72     }
  73 }
  74 #endif  /* _MSC_VER < 1800 */
  75
  76 #elif defined(__APPLE__) || defined(__CYGWIN__) || defined(__FreeBSD__) || \
  77      defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || \
  78      (defined(__sun) && defined(__C99FEATURES__)) || defined(__MINGW32__) || \
  79      (defined(__sun) && defined(__GNUC__)) || defined(ANDROID) || defined(__HAIKU__)
  80
  81 /* fpclassify is available. */
  82
  83 #elif !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600
  84
  85 enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
  86 fpclassify(double x)
  87 {
  88    /* XXX do something better someday */
  89    return FP_NORMAL;
  90 }
  91
  92 #endif
  93
  94 GLbitfield GLAPIENTRY _mesa_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16])
  95 {
  96     GLfloat matrix[16];
  97     GLint tmp;
  98     GLenum currentMode = GL_FALSE;
  99     GLenum desiredMatrix = GL_FALSE;
 100     /* The bitfield returns 1 for each component that is invalid (i.e.
 101      * NaN or Inf).  In case of error, everything is invalid.
 102      */
 103     GLbitfield rv;
 104     register unsigned int i;
 105     unsigned int bit;
 106
 107     /* This data structure defines the mapping between the current matrix
 108      * mode and the desired matrix identifier.
 109      */
 110     static struct {
 111         GLenum currentMode;
 112         GLenum desiredMatrix;
 113     } modes[] = {
 114         {GL_MODELVIEW, GL_MODELVIEW_MATRIX},
 115         {GL_PROJECTION, GL_PROJECTION_MATRIX},
 116         {GL_TEXTURE, GL_TEXTURE_MATRIX},
 117     };
 118
 119     /* Call Mesa to get the current matrix in floating-point form.  First,
 120      * we have to figure out what the current matrix mode is.
 121      */
 122     _mesa_GetIntegerv(GL_MATRIX_MODE, &tmp);
 123     currentMode = (GLenum) tmp;
 124
 125     /* The mode is either GL_FALSE, if for some reason we failed to query
 126      * the mode, or a given mode from the above table.  Search for the
 127      * returned mode to get the desired matrix; if we don't find it,
 128      * we can return immediately, as _mesa_GetInteger() will have
 129      * logged the necessary error already.
 130      */
 131     for (i = 0; i < sizeof(modes)/sizeof(modes[0]); i++) {
 132         if (modes[i].currentMode == currentMode) {
 133             desiredMatrix = modes[i].desiredMatrix;
 134             break;
 135         }
 136     }
 137     if (desiredMatrix == GL_FALSE) {
 138         /* Early error means all values are invalid. */
 139         return 0xffff;
 140     }
 141
 142     /* Now pull the matrix itself. */
 143     _mesa_GetFloatv(desiredMatrix, matrix);
 144
 145     rv = 0;
 146     for (i = 0, bit = 1; i < 16; i++, bit<<=1) {
 147         float normalizedFraction;
 148         int exp;
 149
 150         switch (fpclassify(matrix[i])) {
 151             /* A "subnormal" or denormalized number is too small to be
 152              * represented in normal format; but despite that it's a
 153              * valid floating point number.  FP_ZERO and FP_NORMAL
 154              * are both valid as well.  We should be fine treating
 155              * these three cases as legitimate floating-point numbers.
 156              */
 157             case FP_SUBNORMAL:
 158             case FP_NORMAL:
 159             case FP_ZERO:
 160                 normalizedFraction = (GLfloat)frexp(matrix[i], &exp);
 161                 mantissa[i] = FLOAT_TO_FIXED(normalizedFraction);
 162                 exponent[i] = (GLint) exp;
 163                 break;
 164
 165             /* If the entry is not-a-number or an infinity, then the
 166              * matrix component is invalid.  The invalid flag for
 167              * the component is already set; might as well set the
 168              * other return values to known values.  We'll set
 169              * distinct values so that a savvy end user could determine
 170              * whether the matrix component was a NaN or an infinity,
 171              * but this is more useful for debugging than anything else
 172              * since the standard doesn't specify any such magic
 173              * values to return.
 174              */
 175             case FP_NAN:
 176                 mantissa[i] = INT_TO_FIXED(0);
 177                 exponent[i] = (GLint) 0;
 178                 rv |= bit;
 179                 break;
 180
 181             case FP_INFINITE:
 182                 /* Return +/- 1 based on whether it's a positive or
 183                  * negative infinity.
 184                  */
 185                 if (matrix[i] > 0) {
 186                     mantissa[i] = INT_TO_FIXED(1);
 187                 }
 188                 else {
 189                     mantissa[i] = -INT_TO_FIXED(1);
 190                 }
 191                 exponent[i] = (GLint) 0;
 192                 rv |= bit;
 193                 break;
 194
 195             /* We should never get here; but here's a catching case
 196              * in case fpclassify() is returnings something unexpected.
 197              */
 198             default:
 199                 mantissa[i] = INT_TO_FIXED(2);
 200                 exponent[i] = (GLint) 0;
 201                 rv |= bit;
 202                 break;
 203         }
 204
 205     } /* for each component */
 206
 207     /* All done */
 208     return rv;
 209 }