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root/radiance/ray/src/common/mat4.c
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Comparing ray/src/common/mat4.c (file contents):
Revision 1.5 by greg, Sat Dec 15 15:01:38 1990 UTC vs.
Revision 2.2 by greg, Thu Jun 23 10:22:20 1994 UTC

# Line 12 | Line 12 | static char SCCSid[] = "$SunId$ LBL";
12  
13   #include  "mat4.h"
14  
15 + MAT4  m4ident = MAT4IDENT;
16 +
17   static MAT4  m4tmp;             /* for efficiency */
18  
19  
18 – setident4(m4)
19 – MAT4  m4;
20 – {
21 –        static MAT4  ident = {
22 –                1.,0.,0.,0.,
23 –                0.,1.,0.,0.,
24 –                0.,0.,1.,0.,
25 –                0.,0.,0.,1.,
26 –        };
27 –        copymat4(m4, ident);
28 – }
29 –
30 –
20   multmat4(m4a, m4b, m4c)         /* multiply m4b X m4c and put into m4a */
21   MAT4  m4a;
22   register MAT4  m4b, m4c;
# Line 70 | Line 59 | register MAT4  m4;
59          p3a[1] += m4[3][1];
60          p3a[2] += m4[3][2];
61   }
73 –
74 –
75 – #ifdef  INVMAT
76 – /*
77 – * invmat - computes the inverse of mat into inverse.  Returns 1
78 – * if there exists an inverse, 0 otherwise.  It uses Gaussian Elimination
79 – * method with partial pivoting.
80 – */
81 –
82 – invmat(inverse,mat)
83 – MAT4  mat, inverse;
84 – {
85 – #define SWAP(a,b,t) (t=a,a=b,b=t)
86 – #define ABS(x) (x>=0?x:-(x))
87 –
88 –        register int i,j,k;
89 –        register double temp;
90 –
91 –        copymat4(m4tmp, mat);
92 –        setident(inverse);
93 –
94 –        for(i = 0; i < 4; i++) {
95 –                /* Look for row with largest pivot and swap rows */
96 –                temp = 0; j = -1;
97 –                for(k = i; k < 4; k++)
98 –                        if(ABS(m4tmp[k][i]) > temp) {
99 –                                temp = ABS(m4tmp[k][i]);
100 –                                j = k;
101 –                                }
102 –                if(j == -1)     /* No replacing row -> no inverse */
103 –                        return(0);
104 –                if (j != i)
105 –                        for(k = 0; k < 4; k++) {
106 –                                SWAP(m4tmp[i][k],m4tmp[j][k],temp);
107 –                                SWAP(inverse[i][k],inverse[j][k],temp);
108 –                                }
109 –
110 –                temp = m4tmp[i][i];
111 –                for(k = 0; k < 4; k++) {
112 –                        m4tmp[i][k] /= temp;
113 –                        inverse[i][k] /= temp;
114 –                        }
115 –                for(j = 0; j < 4; j++) {
116 –                        if(j != i) {
117 –                                temp = m4tmp[j][i];
118 –                                for(k = 0; k < 4; k++) {
119 –                                        m4tmp[j][k] -= m4tmp[i][k]*temp;
120 –                                        inverse[j][k] -= inverse[i][k]*temp;
121 –                                        }
122 –                                }
123 –                        }
124 –                }
125 –        return(1);
126 –
127 – #undef ABS
128 – #undef SWAP
129 – }
130 – #endif

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