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 "c99_math.h"
17 #include "glheader.h"
18 #include "querymatrix.h"
19 #include "main/get.h"
20 #include "util/macros.h"
21
22
23 /**
24 * This is from the GL_OES_query_matrix extension specification:
25 *
26 * GLbitfield glQueryMatrixxOES( GLfixed mantissa[16],
27 * GLint exponent[16] )
28 * mantissa[16] contains the contents of the current matrix in GLfixed
29 * format. exponent[16] contains the unbiased exponents applied to the
30 * matrix components, so that the internal representation of component i
31 * is close to mantissa[i] * 2^exponent[i]. The function returns a status
32 * word which is zero if all the components are valid. If
33 * status & (1<<i) != 0, the component i is invalid (e.g., NaN, Inf).
34 * The implementations are not required to keep track of overflows. In
35 * that case, the invalid bits are never set.
36 */
37
38 #define INT_TO_FIXED(x) ((GLfixed) ((x) << 16))
39 #define FLOAT_TO_FIXED(x) ((GLfixed) ((x) * 65536.0))
40
41
42 GLbitfield GLAPIENTRY
_mesa_QueryMatrixxOES(GLfixed mantissa[16],GLint exponent[16])43 _mesa_QueryMatrixxOES(GLfixed mantissa[16], GLint exponent[16])
44 {
45 GLfloat matrix[16];
46 GLint tmp;
47 GLenum currentMode = GL_FALSE;
48 GLenum desiredMatrix = GL_FALSE;
49 /* The bitfield returns 1 for each component that is invalid (i.e.
50 * NaN or Inf). In case of error, everything is invalid.
51 */
52 GLbitfield rv;
53 unsigned i, bit;
54
55 /* This data structure defines the mapping between the current matrix
56 * mode and the desired matrix identifier.
57 */
58 static const struct {
59 GLenum currentMode;
60 GLenum desiredMatrix;
61 } modes[] = {
62 {GL_MODELVIEW, GL_MODELVIEW_MATRIX},
63 {GL_PROJECTION, GL_PROJECTION_MATRIX},
64 {GL_TEXTURE, GL_TEXTURE_MATRIX},
65 };
66
67 /* Call Mesa to get the current matrix in floating-point form. First,
68 * we have to figure out what the current matrix mode is.
69 */
70 _mesa_GetIntegerv(GL_MATRIX_MODE, &tmp);
71 currentMode = (GLenum) tmp;
72
73 /* The mode is either GL_FALSE, if for some reason we failed to query
74 * the mode, or a given mode from the above table. Search for the
75 * returned mode to get the desired matrix; if we don't find it,
76 * we can return immediately, as _mesa_GetInteger() will have
77 * logged the necessary error already.
78 */
79 for (i = 0; i < ARRAY_SIZE(modes); i++) {
80 if (modes[i].currentMode == currentMode) {
81 desiredMatrix = modes[i].desiredMatrix;
82 break;
83 }
84 }
85 if (desiredMatrix == GL_FALSE) {
86 /* Early error means all values are invalid. */
87 return 0xffff;
88 }
89
90 /* Now pull the matrix itself. */
91 _mesa_GetFloatv(desiredMatrix, matrix);
92
93 rv = 0;
94 for (i = 0, bit = 1; i < 16; i++, bit<<=1) {
95 float normalizedFraction;
96 int exp;
97
98 switch (fpclassify(matrix[i])) {
99 case FP_SUBNORMAL:
100 case FP_NORMAL:
101 case FP_ZERO:
102 /* A "subnormal" or denormalized number is too small to be
103 * represented in normal format; but despite that it's a
104 * valid floating point number. FP_ZERO and FP_NORMAL
105 * are both valid as well. We should be fine treating
106 * these three cases as legitimate floating-point numbers.
107 */
108 normalizedFraction = (GLfloat)frexp(matrix[i], &exp);
109 mantissa[i] = FLOAT_TO_FIXED(normalizedFraction);
110 exponent[i] = (GLint) exp;
111 break;
112
113 case FP_NAN:
114 /* If the entry is not-a-number or an infinity, then the
115 * matrix component is invalid. The invalid flag for
116 * the component is already set; might as well set the
117 * other return values to known values. We'll set
118 * distinct values so that a savvy end user could determine
119 * whether the matrix component was a NaN or an infinity,
120 * but this is more useful for debugging than anything else
121 * since the standard doesn't specify any such magic
122 * values to return.
123 */
124 mantissa[i] = INT_TO_FIXED(0);
125 exponent[i] = (GLint) 0;
126 rv |= bit;
127 break;
128
129 case FP_INFINITE:
130 /* Return +/- 1 based on whether it's a positive or
131 * negative infinity.
132 */
133 if (matrix[i] > 0) {
134 mantissa[i] = INT_TO_FIXED(1);
135 }
136 else {
137 mantissa[i] = -INT_TO_FIXED(1);
138 }
139 exponent[i] = (GLint) 0;
140 rv |= bit;
141 break;
142
143 default:
144 /* We should never get here; but here's a catching case
145 * in case fpclassify() is returnings something unexpected.
146 */
147 mantissa[i] = INT_TO_FIXED(2);
148 exponent[i] = (GLint) 0;
149 rv |= bit;
150 break;
151 }
152
153 } /* for each component */
154
155 /* All done */
156 return rv;
157 }
158