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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* t_func.c - routine for procedural textures. |
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*/ |
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|
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#include "copyright.h" |
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|
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#include "ray.h" |
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|
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#include "func.h" |
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|
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/* |
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* A procedural texture perturbs the surface normal |
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* at the point of intersection with an object. It has |
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* the form: |
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* |
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* modifier texfunc name |
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* 4+ xvarname yvarname zvarname filename xf |
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* 0 |
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* n A1 A2 .. |
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* |
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* Filename is the name of the file where the variable definitions |
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* can be found. The list of real arguments can be accessed by |
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* definitions in the file. The xf is a transformation to get |
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* from the original coordinates to the current coordinates. |
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*/ |
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|
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|
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t_func(m, r) /* compute texture for ray */ |
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register OBJREC *m; |
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register RAY *r; |
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{ |
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FVECT disp; |
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double d; |
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register MFUNC *mf; |
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register int i; |
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|
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if (m->oargs.nsargs < 4) |
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objerror(m, USER, "bad # arguments"); |
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mf = getfunc(m, 3, 0x7, 1); |
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setfunc(m, r); |
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errno = 0; |
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for (i = 0; i < 3; i++) { |
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disp[i] = evalue(mf->ep[i]); |
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if (errno) { |
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objerror(m, WARNING, "compute error"); |
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return(0); |
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} |
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} |
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if (mf->f != &unitxf) |
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multv3(disp, disp, mf->f->xfm); |
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if (r->rox != NULL) { |
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multv3(disp, disp, r->rox->f.xfm); |
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d = 1.0 / (mf->f->sca * r->rox->f.sca); |
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} else |
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d = 1.0 / mf->f->sca; |
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for (i = 0; i < 3; i++) |
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r->pert[i] += disp[i] * d; |
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return(0); |
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} |
