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(__DragonFly__) || (defined(__sun) && defined(__C99FEATURES__))
  75
  76 /* fpclassify is available. */
  77
  78 #elif !defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 600
  79
  80 enum {FP_NAN, FP_INFINITE, FP_ZERO, FP_SUBNORMAL, FP_NORMAL}
  81 fpclassify(double x)
  82 {
  83    /* XXX do something better someday */
  84    return FP_NORMAL;
  85 }
  86
  87 #endif
  88
  89 extern GLbitfield GL_APIENTRY _es_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16]);
  90
  91 /* The Mesa functions we'll need */
  92 extern void GL_APIENTRY _mesa_GetIntegerv(GLenum pname, GLint *params);
  93 extern void GL_APIENTRY _mesa_GetFloatv(GLenum pname, GLfloat *params);
  94
  95 GLbitfield GL_APIENTRY _es_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16])
  96 {
  97     GLfloat matrix[16];
  98     GLint tmp;
  99     GLenum currentMode = GL_FALSE;
 100     GLenum desiredMatrix = GL_FALSE;
 101     /* The bitfield returns 1 for each component that is invalid (i.e.
 102      * NaN or Inf).  In case of error, everything is invalid.
 103      */
 104     GLbitfield rv;
 105     register unsigned int i;
 106     unsigned int bit;
 107
 108     /* This data structure defines the mapping between the current matrix
 109      * mode and the desired matrix identifier.
 110      */
 111     static struct {
 112         GLenum currentMode;
 113         GLenum desiredMatrix;
 114     } modes[] = {
 115         {GL_MODELVIEW, GL_MODELVIEW_MATRIX},
 116         {GL_PROJECTION, GL_PROJECTION_MATRIX},
 117         {GL_TEXTURE, GL_TEXTURE_MATRIX},
 118 #if 0
 119         /* this doesn't exist in GLES */
 120         {GL_COLOR, GL_COLOR_MATRIX},
 121 #endif
 122     };
 123
 124     /* Call Mesa to get the current matrix in floating-point form.  First,
 125      * we have to figure out what the current matrix mode is.
 126      */
 127     _mesa_GetIntegerv(GL_MATRIX_MODE, &tmp);
 128     currentMode = (GLenum) tmp;
 129
 130     /* The mode is either GL_FALSE, if for some reason we failed to query
 131      * the mode, or a given mode from the above table.  Search for the
 132      * returned mode to get the desired matrix; if we don't find it,
 133      * we can return immediately, as _mesa_GetInteger() will have
 134      * logged the necessary error already.
 135      */
 136     for (i = 0; i < sizeof(modes)/sizeof(modes[0]); i++) {
 137         if (modes[i].currentMode == currentMode) {
 138             desiredMatrix = modes[i].desiredMatrix;
 139             break;
 140         }
 141     }
 142     if (desiredMatrix == GL_FALSE) {
 143         /* Early error means all values are invalid. */
 144         return 0xffff;
 145     }
 146
 147     /* Now pull the matrix itself. */
 148     _mesa_GetFloatv(desiredMatrix, matrix);
 149
 150     rv = 0;
 151     for (i = 0, bit = 1; i < 16; i++, bit<<=1) {
 152         float normalizedFraction;
 153         int exp;
 154
 155         switch (fpclassify(matrix[i])) {
 156             /* A "subnormal" or denormalized number is too small to be
 157              * represented in normal format; but despite that it's a
 158              * valid floating point number.  FP_ZERO and FP_NORMAL
 159              * are both valid as well.  We should be fine treating
 160              * these three cases as legitimate floating-point numbers.
 161              */
 162             case FP_SUBNORMAL:
 163             case FP_NORMAL:
 164             case FP_ZERO:
 165                 normalizedFraction = (GLfloat)frexp(matrix[i], &exp);
 166                 mantissa[i] = FLOAT_TO_FIXED(normalizedFraction);
 167                 exponent[i] = (GLint) exp;
 168                 break;
 169
 170             /* If the entry is not-a-number or an infinity, then the
 171              * matrix component is invalid.  The invalid flag for
 172              * the component is already set; might as well set the
 173              * other return values to known values.  We'll set
 174              * distinct values so that a savvy end user could determine
 175              * whether the matrix component was a NaN or an infinity,
 176              * but this is more useful for debugging than anything else
 177              * since the standard doesn't specify any such magic
 178              * values to return.
 179              */
 180             case FP_NAN:
 181                 mantissa[i] = INT_TO_FIXED(0);
 182                 exponent[i] = (GLint) 0;
 183                 rv |= bit;
 184                 break;
 185
 186             case FP_INFINITE:
 187                 /* Return +/- 1 based on whether it's a positive or
 188                  * negative infinity.
 189                  */
 190                 if (matrix[i] > 0) {
 191                     mantissa[i] = INT_TO_FIXED(1);
 192                 }
 193                 else {
 194                     mantissa[i] = -INT_TO_FIXED(1);
 195                 }
 196                 exponent[i] = (GLint) 0;
 197                 rv |= bit;
 198                 break;
 199
 200             /* We should never get here; but here's a catching case
 201              * in case fpclassify() is returnings something unexpected.
 202              */
 203             default:
 204                 mantissa[i] = INT_TO_FIXED(2);
 205                 exponent[i] = (GLint) 0;
 206                 rv |= bit;
 207                 break;
 208         }
 209
 210     } /* for each component */
 211
 212     /* All done */
 213     return rv;
 214 }