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/*
* stripe.c
*
* Copyright (C) 1989, 1991, Craig E. Kolb
* All rights reserved.
*
* This software may be freely copied, modified, and redistributed
* provided that this copyright notice is preserved on all copies.
*
* You may not distribute this software, in whole or in part, as part of
* any commercial product without the express consent of the authors.
*
* There is no warranty or other guarantee of fitness of this software
* for any purpose. It is provided solely "as is".
*
* $Id$
*
* $Log$
*/
#include "texture.h"
#include "stripe.h"
Stripe *
StripeCreate(surf, width, bump, mapping)
Surface *surf;
Float width, bump;
Mapping *mapping;
{
Stripe *stripe;
stripe = (Stripe *)Malloc(sizeof(Stripe));
stripe->surf = surf;
stripe->mapping = mapping;
stripe->width = width;
stripe->bump = bump;
return stripe;
}
void
StripeApply(stripe, prim, ray, pos, norm, gnorm, surf)
Stripe *stripe;
Object *prim;
Vector *ray, *pos, *norm, *gnorm;
Surface *surf;
{
Vector dpdu, dpdv;
Float fu, fv, u, v;
TextToUV(stripe->mapping, prim, pos, gnorm, &u, &v, &dpdu, &dpdv);
u -= floor(u);
v -= floor(v);
/*
* s s s
* | | | | |
* 1 +-+------------+
* |X|\^^^^^^^^^^/| } s
* |X|<+--------+>|
* |X|<| |>|
* |X|<| |>|
* |X|<| |>|
* v |X|<| |>|
* |X|<| |>|
* |X|<| |>|
* |X|<+--------+>|
* |X|/vvvvvvvvvv\| } s
* |X+------------+
* |XXXXXXXXXXXXXX| } s
* 0 +--------------+
* 0 1
* u
*
* where ^ == positive fv, 0 fu, original surf.
* v == negative fv, 0 fu, original surf.
* > == positive fu, 0 fv, original surf.
* < == negative fu, 0 fv, original surf.
* blank == 0 fu, 0 fv, original surf.
* X == 0 fu, 0 fv, alternate surf.
* for stripe->bump > 0. For stripe->bump < 0., change signs.
*/
if (u > 2*stripe->width && v > 2*stripe->width &&
u <= 1. - stripe->width && v <= 1. - stripe->width)
/* flat surface */
return;
else if (u < stripe->width || v < stripe->width) {
/* on the bottom of the bump. */
*surf = *stripe->surf;
return;
}
/*
* Lower u & v edges are the 'flat' part of the bump --
* make our lives simpler below by 'removing' this area
* from u & v.
*/
u = (u - stripe->width) / (1. - stripe->width);
v = (v - stripe->width) / (1. - stripe->width);
/*
* Now the hard part -- where's the bump?
*/
if (v < u) {
if (v < 1. - u) {
/* bottom */
fu = 0.;
fv = -stripe->bump;
} else {
/* right */
fu = stripe->bump;
fv = 0.;
}
} else {
if (v < 1. - u) {
/* left */
fu = -stripe->bump;
fv = 0.;
} else {
/* top */
fu = 0.;
fv = stripe->bump;
}
}
MakeBump(norm, &dpdu, &dpdv, fu, fv);
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.