void
PseudoSpace(struct XYspace *S, /* coordinate space structure to fill out */
double M[2][2]) /* matrix that will become 'tofract.normal' */
{
S->type = SPACETYPE;
S->flag = ISPERMANENT(ON) + ISIMMORTAL(ON);
S->references = 2; /* 3-26-91 added PNM */
S->tofract.normal[0][0] = M[0][0];
S->tofract.normal[1][0] = M[1][0];
S->tofract.normal[0][1] = M[0][1];
S->tofract.normal[1][1] = M[1][1];
FillOutFcns(S);
}
void InitSpaces(void)
{
IDENTITY->type = SPACETYPE;
FillOutFcns(IDENTITY);
contexts[NULLCONTEXT].normal[1][0]
= contexts[NULLCONTEXT].normal[0][1]
= contexts[NULLCONTEXT].inverse[1][0]
= contexts[NULLCONTEXT].inverse[0][1] = 0.0;
contexts[NULLCONTEXT].normal[0][0]
= contexts[NULLCONTEXT].normal[1][1]
= contexts[NULLCONTEXT].inverse[0][0]
= contexts[NULLCONTEXT].inverse[1][1] = 1.0;
USER->flag |= ISIMMORTAL(ON);
CoerceInverse(USER);
}
/*
The following macro forces a space to have an inverse:
*/
#define CoerceInverse(S) if (!HASINVERSE((S)->flag)) { \
MatrixInvert((S)->tofract.normal, (S)->tofract.inverse); (S)->flag |= HASINVERSE(ON); }
/*
:h3.IDENTITY Space
IDENTITY space is (logically) the space corresponding to the identity
transformation matrix. However, since all our transformation matrices
have a common FRACTFLOAT scale factor to convert to 'fractpel's, that
is actually what we store in 'tofract' matrix of IDENTITY:
*/
static struct XYspace identity = { SPACETYPE, ISPERMANENT(ON) + ISIMMORTAL(ON)
+ HASINVERSE(ON), 2, /* added 3-26-91 PNM */
NULL, NULL,
NULL, NULL, NULL, NULL,
INVALIDID + 1, 0,
{{{FRACTFLOAT, 0.0}, {0.0, FRACTFLOAT}},
{{1.0/FRACTFLOAT, 0.0}, {0.0, 1.0/FRACTFLOAT}}},
{{0, 0}, {0, 0}}};
struct XYspace *IDENTITY = &identity;
/*
*/
#define MAXCONTEXTS 16
static struct doublematrix contexts[MAXCONTEXTS];