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 "GLES/gl.h"
  18 #include "GLES/glext.h"
  19
  20
  21 /**
  22  * This is from the GL_OES_query_matrix extension specification:
  23  *
  24  *  GLbitfield glQueryMatrixxOES( GLfixed mantissa[16],
  25  *                                GLint   exponent[16] )
  26  *  mantissa[16] contains the contents of the current matrix in GLfixed
  27  *  format.  exponent[16] contains the unbiased exponents applied to the
  28  *  matrix components, so that the internal representation of component i
  29  *  is close to mantissa[i] * 2^exponent[i].  The function returns a status
  30  *  word which is zero if all the components are valid. If
  31  *  status & (1<<i) != 0, the component i is invalid (e.g., NaN, Inf).
  32  *  The implementations are not required to keep track of overflows.  In
  33  *  that case, the invalid bits are never set.
  34  */
  35
  36 #define INT_TO_FIXED(x) ((GLfixed) ((x) << 16))
  37 #define FLOAT_TO_FIXED(x) ((GLfixed) ((x) * 65536.0))
  38
  39 #if defined(WIN32) || defined(_WIN32_WCE)
  40 /* Oddly, the fpclassify() function doesn't exist in such a form
  41  * on Windows.  This is an implementation using slightly different
  42  * lower-level Windows functions.
  43  */
  44 #include <float.h>
  45
  46 enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
  47 fpclassify(double x)
  48 {
  49     switch(_fpclass(x)) {
  50         case _FPCLASS_SNAN: /* signaling NaN */
  51         case _FPCLASS_QNAN: /* quiet NaN */
  52             return FP_NAN;
  53         case _FPCLASS_NINF: /* negative infinity */
  54         case _FPCLASS_PINF: /* positive infinity */
  55             return FP_INFINITE;
  56         case _FPCLASS_NN:   /* negative normal */
  57         case _FPCLASS_PN:   /* positive normal */
  58             return FP_NORMAL;
  59         case _FPCLASS_ND:   /* negative denormalized */
  60         case _FPCLASS_PD:   /* positive denormalized */
  61             return FP_SUBNORMAL;
  62         case _FPCLASS_NZ:   /* negative zero */
  63         case _FPCLASS_PZ:   /* positive zero */
  64             return FP_ZERO;
  65         default:
  66             /* Should never get here; but if we do, this will guarantee
  67              * that the pattern is not treated like a number.
  68              */
  69             return FP_NAN;
  70     }
  71 }
  72
  73 #elif defined(__APPLE__) || defined(__CYGWIN__) || defined(__FreeBSD__) || \
  74      defined(__OpenBSD__) || defined(__NetBSD__) || defined(__DragonFly__) || \
  75      (defined(__sun) && defined(__C99FEATURES__))
  76
  77 /* fpclassify is available. */
  78
  79 #elif !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600
  80
  81 enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
  82 fpclassify(double x)
  83 {
  84    /* XXX do something better someday */
  85    return FP_NORMAL;
  86 }
  87
  88 #endif
  89
  90 extern GLbitfield GL_APIENTRY _es_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16]);
  91
  92 /* The Mesa functions we'll need */
  93 extern void GL_APIENTRY _mesa_GetIntegerv(GLenum pname, GLint *params);
  94 extern void GL_APIENTRY _mesa_GetFloatv(GLenum pname, GLfloat *params);
  95
  96 GLbitfield GL_APIENTRY _es_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16])
  97 {
  98     GLfloat matrix[16];
  99     GLint tmp;
 100     GLenum currentMode = GL_FALSE;
 101     GLenum desiredMatrix = GL_FALSE;
 102     /* The bitfield returns 1 for each component that is invalid (i.e.
 103      * NaN or Inf).  In case of error, everything is invalid.
 104      */
 105     GLbitfield rv;
 106     register unsigned int i;
 107     unsigned int bit;
 108
 109     /* This data structure defines the mapping between the current matrix
 110      * mode and the desired matrix identifier.
 111      */
 112     static struct {
 113         GLenum currentMode;
 114         GLenum desiredMatrix;
 115     } modes[] = {
 116         {GL_MODELVIEW, GL_MODELVIEW_MATRIX},
 117         {GL_PROJECTION, GL_PROJECTION_MATRIX},
 118         {GL_TEXTURE, GL_TEXTURE_MATRIX},
 119 #if 0
 120         /* this doesn't exist in GLES */
 121         {GL_COLOR, GL_COLOR_MATRIX},
 122 #endif
 123     };
 124
 125     /* Call Mesa to get the current matrix in floating-point form.  First,
 126      * we have to figure out what the current matrix mode is.
 127      */
 128     _mesa_GetIntegerv(GL_MATRIX_MODE, &tmp);
 129     currentMode = (GLenum) tmp;
 130
 131     /* The mode is either GL_FALSE, if for some reason we failed to query
 132      * the mode, or a given mode from the above table.  Search for the
 133      * returned mode to get the desired matrix; if we don't find it,
 134      * we can return immediately, as _mesa_GetInteger() will have
 135      * logged the necessary error already.
 136      */
 137     for (i = 0; i < sizeof(modes)/sizeof(modes[0]); i++) {
 138         if (modes[i].currentMode == currentMode) {
 139             desiredMatrix = modes[i].desiredMatrix;
 140             break;
 141         }
 142     }
 143     if (desiredMatrix == GL_FALSE) {
 144         /* Early error means all values are invalid. */
 145         return 0xffff;
 146     }
 147
 148     /* Now pull the matrix itself. */
 149     _mesa_GetFloatv(desiredMatrix, matrix);
 150
 151     rv = 0;
 152     for (i = 0, bit = 1; i < 16; i++, bit<<=1) {
 153         float normalizedFraction;
 154         int exp;
 155
 156         switch (fpclassify(matrix[i])) {
 157             /* A "subnormal" or denormalized number is too small to be
 158              * represented in normal format; but despite that it's a
 159              * valid floating point number.  FP_ZERO and FP_NORMAL
 160              * are both valid as well.  We should be fine treating
 161              * these three cases as legitimate floating-point numbers.
 162              */
 163             case FP_SUBNORMAL:
 164             case FP_NORMAL:
 165             case FP_ZERO:
 166                 normalizedFraction = (GLfloat)frexp(matrix[i], &exp);
 167                 mantissa[i] = FLOAT_TO_FIXED(normalizedFraction);
 168                 exponent[i] = (GLint) exp;
 169                 break;
 170
 171             /* If the entry is not-a-number or an infinity, then the
 172              * matrix component is invalid.  The invalid flag for
 173              * the component is already set; might as well set the
 174              * other return values to known values.  We'll set
 175              * distinct values so that a savvy end user could determine
 176              * whether the matrix component was a NaN or an infinity,
 177              * but this is more useful for debugging than anything else
 178              * since the standard doesn't specify any such magic
 179              * values to return.
 180              */
 181             case FP_NAN:
 182                 mantissa[i] = INT_TO_FIXED(0);
 183                 exponent[i] = (GLint) 0;
 184                 rv |= bit;
 185                 break;
 186
 187             case FP_INFINITE:
 188                 /* Return +/- 1 based on whether it's a positive or
 189                  * negative infinity.
 190                  */
 191                 if (matrix[i] > 0) {
 192                     mantissa[i] = INT_TO_FIXED(1);
 193                 }
 194                 else {
 195                     mantissa[i] = -INT_TO_FIXED(1);
 196                 }
 197                 exponent[i] = (GLint) 0;
 198                 rv |= bit;
 199                 break;
 200
 201             /* We should never get here; but here's a catching case
 202              * in case fpclassify() is returnings something unexpected.
 203              */
 204             default:
 205                 mantissa[i] = INT_TO_FIXED(2);
 206                 exponent[i] = (GLint) 0;
 207                 rv |= bit;
 208                 break;
 209         }
 210
 211     } /* for each component */
 212
 213     /* All done */
 214     return rv;
 215 }