Usenet 1994 January/usenetsourcesnewsgroupsinfomagicjanuary1994.iso/sources/misc/volume21/rayshade/part13

Text File | 1991-07-21 | 45.7 KB | 1,619 lines

Newsgroups: comp.sources.misc
From: Rayshade Construction Co. <[e-mail]>
Subject:  v21i016:  rayshade - A raytracing package for UNIX, Part13/19
Message-ID: <[e-mail]>
X-Md4-Signature: 53f3ff77cd6fa10e38fc8bd025d16e01
Date: Sun, 21 Jul 1991 03:38:19 GMT
Approved: [e-mail]

Submitted-by: Rayshade Construction Co. <[e-mail]>
Posting-number: Volume 21, Issue 16
Archive-name: rayshade/part13
Environment: UNIX, !16BIT

#! /bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#        "End of archive 13 (of 19)."
# Contents:  Doc/Guide/surfaces.tex libray/libcommon/transform.c
#   libray/libobj/csg.c libshade/shade.c
# Wrapped by kolb@woody on Wed Jul 17 17:56:52 1991
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'Doc/Guide/surfaces.tex' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'Doc/Guide/surfaces.tex'\"
else
echo shar: Extracting \"'Doc/Guide/surfaces.tex'\" \(10193 characters\)
sed "s/^X//" >'Doc/Guide/surfaces.tex' <<'END_OF_FILE'
X\chapter{Surfaces and Atmospheric Effects}
X
XSurfaces are used to control the interaction between light sources and
Xobjects.  A surface specification consists of information
Xabout how the light interacts with both the exterior and
Xinterior of an object .
XFor non-closed objects, such as polygons,
Xthe ``interior'' of an object is the ``other side'' of the object's surface
Xrelative to the origin of a ray.
X
XRayshade usually ensures that a primitive's surface normal is pointing
Xtowards the origin of the incident ray when performing shading
Xcalculations.  Exceptions to this rule are transparent primitives, for
Xwhich rayshade uses the direction of the surface normal to determine if
Xthe incident ray is entering or exiting the object.
XAll non-transparent primitives will, in effect, be double-sided.
X
X\section{Surface Description}
X
XA surface definition consists of a number of component keywords, each
Xof which is usually followed by either a single number or a red-green-blue
Xcolor triple.   Each of the values in the color triple are normalized,
Xwith zero indicating zero intensity, and one indicating full intensity.
X
XIf any surface component is left unspecified, its value defaults to zero,
Xwith the exception of the index of refraction, which is assigned the
Xdefault index of refraction (normally 1.0).
X
XSurface descriptions are used in rayshade to compute the color of a ray
Xthat strikes the surface at a point \evec{P}. The normal to the surface
Xat \evec{P}, \evec{N}, is also computed.
X
X\begin{defkey}{ambient}{\evec{color}}
X    Use the given {\em color} to approximate those surface-surface
X    interactions (e.g., diffuse interreflection) not modeled by the
X    ray tracing process.
X\end{defkey}
XA surface's ambient color is always applied to a ray.  The color
Xapplied is computed by multiplying the ambient color by the intensity
Xof the ambient light source.
X
XIf \evec{P} is in shadow with respect to a given light source,
Xthat light source makes no contribution to the shading of \evec{P}.
X
X\begin{defkey}{diffuse}{\evec{color}}
X    Specifies the diffuse color.
X\end{defkey}
XThe diffuse contribution from each non-shadowed light source at \evec{P}
Xis equal to the diffuse color of the surface scaled by the cosine of
Xthe angle between \evec{N}
Xand the vector from \evec{P} to the light source.
X
X\begin{defkey}{specular}{\evec{color}}
X    Specifies the base color of specular reflections.
X\end{defkey}
X
X\begin{defkey}{specpow}{{\em exponent}}
X    Specifies the specular highlight) exponent.
X\end{defkey}
XThe intensity of specular highlights from light sources are
Xscaled by the specular color of the surface.
X
X\begin{defkey}{reflect}{{\em reflectivity}}
X    Specifies the specular reflectivity of the surface.  If non-zero,
X    reflected rays will be spawned.
X\end{defkey}
XThe intensity of specularly reflected rays will be proportional to
Xthe specular color of the surface scaled by the reflectivity.
X
X\begin{defkey}{transp}{{\em transparency}}
X    Specifies the specular transmissivity of the surface.  If
X    non-zero,
X    transmitted (refracted) rays will be spawned.
X\end{defkey}
X
X\begin{defkey}{body}{\evec{color}}
X    Specifies the body color of the object.  The body color
X    affects the color of rays that are transmitted through the
X    object.
X\end{defkey}
X
X\begin{defkey}{extinct}{{\em coefficient}}
X    Specifies the extinction coefficient of the interior
X    of the object.
X\end{defkey}
XThe extinction coefficient is raised to a power equal to the distance
Xthe transmitted ray travels through the object.
XThe overall intensity of specularly transmitted rays will be proportional to
Xthis factor multiplied by the surface's body color
Xmultiplied by the transparency of the object.
X
X\begin{defkey}{index}{{\em N}}
X    Specifies the index of refraction.  The default value is equal
X    to the index of refraction of the atmosphere surrounding the eye.
X\end{defkey}
X
X\begin{defkey}{translucency}{{\em translu} \evec{color} {\em stexp}}
X    Specifies the translucency, diffusely transmitted color,
X    and Phong exponent for transmitted specular highlights.
X\end{defkey}
XIf a light source illuminates a translucent surface from the side opposite
Xthat from which a ray approaches, illumination computations are performed,
Xusing the given color as the surface's diffuse color, and the given
Xexponent as the Phong highlight exponent.  The resulting color is then
Xscaled by the surface's translucency.
X
X\section{Atmospheric Effects}
X
XAny number of atmospheric effects may also be associated with a surface.
XThese effects will be applied to those rays that are transmitted through
Xthe surface.  Applying atmospheric effects to opaque objects is a waste
Xof input file.
X
X\begin{defkey}{fog}{\evec{color} \evec{thinness}}
XAdd exponential fog with the specified {\em thinness} and {\em color}.
X\end{defkey}
XFog is simulated by blending the color of the fog with the color of
Xeach ray.  The amount of fog color blended into a ray color is an exponential
Xfunction of the distance from the ray origin to the point of intersection
Xdivided by the specified {\em thinness} for each color channel.
XIf the distance is equal to {\em thinness},
Xa ray's new color will be half of the fog color plus half its
Xoriginal color.
X
X\begin{defkey}{mist}{\evec{color} \evec{thinness} {\em zero scale}}
XAdd global low-altitude mist of the specified color.  The color of
Xa ray is modulated by a fog with density that varies linearly with
Xthe difference in $z$ coordinate (altitude) between the ray origin and
Xthe point of intersection.  The thinness values specify the transmissivity
Xof the fog for each color channel.
XThe base altitude of the
Xmist is given by {\em zero}, and the apparent height of the mist can
Xbe modulated using {\em scale}, which scales the difference in
Xaltitude used to compute the fog.
X\end{defkey}
X
X\section {The Default Medium}
X
XThe default medium is the medium which surrounds and encompasses
Xall of the objects in the scene; it is the ``air'' through which eye
Xrays usually travel before hitting an object.  The properties of
Xthe default medium may be modified through the use of the {\tt atmosphere}
Xkeyword.
X
X\begin{defkey}{atmosphere}{[{\em N\/}] [{\em atmospheric effects}]}
XIf given, {\em N} specifies the index of refraction of the default
Xmedium.  The default is 1.0.  Any atmospheric effects listed are applied
Xto rays that are exterior to every object in the scene (e.g., rays
Xemanating from the camera).
X\end{defkey}
X
X\begin{verbatim}
X    /*
X     * Red sphere on a grey plane, with fog.
X     */
X    eyep 0. -10. 2.
X    atmosphere fog  .8 .8 .8 14. 14. 14.
X    plane 0 0 0  0 0 1
X    sphere diffuse 0.8 0 0   1.5  0 0 1.5
X\end{verbatim}
X
X\section {Surface Specification}
X
X{\em Rayshade} provides a number of ways to define surfaces and to
Xbind these surfaces to objects.  The most straight-forward method
Xof surface specification is to simply list the surface properties to
Xbe used.
XAlternatively, one may associate a name with a given surface.
XThis name may subsequently be used to refer to that surface.
X
X\begin{defkey}{surface}{{\em name\/} $<${\em Surface Definition}$>$}
X    Associate the given collection of surface attributes with the
X    given name.
X\end{defkey}
X
XThe binding of a collection of surface properties to a given object
Xis accomplished in a bottom-up manner; the surface that ``closest''
Xin the modeling tree to the primitive being rendered is the one that
Xis used to give the primitive its appearance.
X
XAn object that has no surface bound to it is assigned a default surface
Xthat give an object the appearance of white plastic.
X
XThe first
Xand most direct way to bind a surface to a primitive
Xis by specifying the surface to be bound to
Xthe primitive when it is instantiated.
XThis is accomplished
Xby inserting a list of surface attributes or a surface name after
Xthe primitive's type keyword and before the actual primitive data.
X
X\begin{verbatim}
X    /*
X     * A red 'mud' colored sphere reseting on a
X     * white sphere. To the right is a sphere with
X     * default surface attributes.
X     */
X    surface mud ambient .03 0. 0.  diffuse .7 .3 0.
X    sphere  ambient .05 .05 .05 diffuse .7 .7 .7   1. 0 0 0
X    sphere mud  1. 0 0 2
X    sphere 1. 1.5 0 0
X\end{verbatim}
X
XHere, we define a red surface named ``mud''.  We then instantiate
Xa sphere, which has a diffuse white surface bound to it.  The
Xnext line instantiates a sphere with the defined ``mud'' surface bound
Xto it.  The last line instantiates a sphere with no surface bound to it;
Xit is assigned the default surface by {\em rayshade}.
X
XThe {\tt applysurf} keyword may be used to set the default surface
Xcharacteristics for the aggregate object currently being defined.
X
X\begin{defkey}{applysurf}{$<${\em Surface Specification}$>$}
XThe specified surface is applied to all following
Xinstantiated objects that do not have surfaces associated with them.
XThe scope of this keyword is limited to the aggregate currently
Xbeing defined.
X\end{defkey}
X
X\begin{verbatim}
X    /*
X     * Mirrored ball and cylinder sitting on 'default' plane.
X     */
X    surface mirror .01 .01 .01  diffuse .05 .05 .05
X            specular .8 .8 .8 speccoef 20  reflect 0.95
X    plane 0 0 0  0 0 1
X    applysurf mirror
X    sphere 1 0 0 0
X    cylinder 1  3 0 0  3 0 3
X\end{verbatim}
X
XFor convenience, the name {\tt cursurf} may be used to refer to the
Xcurrent default surface.
X
XThe utility of bottom-up binding of surfaces lies in the fact that
Xone may be as adamant or as noncommittal about
Xsurface binding as one sees fit when defining objects.  For example,
Xone could define a king chess piece consisting of triangles that have no
Xsurface bound to them, save for the cross on top, which has
Xa gold-colored surface associated with it.  One may then instantiate
Xthe king twice, once applying a black surface, and once applying
Xa white surface.  The result:  a black king and a white king, each
Xadorned with a golden cross.
X
X\begin{verbatim}
X    surface white ...
X    surface black ...
X    surface gold  ...
X    ...
X    define cross
X            box x y z  x y z
X            ...
X    defend
X    define king
X            triangle x y z  x y z  x y z
X            ...
X            object gold cross
X    defend
X
X    object white king translate 1. 0 0
X    object black king
X\end{verbatim}
END_OF_FILE
if test 10193 -ne `wc -c <'Doc/Guide/surfaces.tex'`; then
    echo shar: \"'Doc/Guide/surfaces.tex'\" unpacked with wrong size!
fi
# end of 'Doc/Guide/surfaces.tex'
fi
if test -f 'libray/libcommon/transform.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'libray/libcommon/transform.c'\"
else
echo shar: Extracting \"'libray/libcommon/transform.c'\" \(10691 characters\)
sed "s/^X//" >'libray/libcommon/transform.c' <<'END_OF_FILE'
X/*
X * transform.c
X *
X * Copyright (C) 1989, 1991, Craig E. Kolb
X * All rights reserved.
X *
X * This software may be freely copied, modified, and redistributed
X * provided that this copyright notice is preserved on all copies.
X *
X * You may not distribute this software, in whole or in part, as part of
X * any commercial product without the express consent of the authors.
X *
X * There is no warranty or other guarantee of fitness of this software
X * for any purpose.  It is provided solely "as is".
X *
X * $Id: transform.c,v 4.0 91/07/17 14:32:25 kolb Exp Locker: kolb $
X *
X * $Log:    transform.c,v $
X * Revision 4.0  91/07/17  14:32:25  kolb
X * Initial version.
X *
X */
X#include "common.h"
X
X/*
X * Matrices are indexed row-first; that is:
X * matrix[ROW][COLUMN]
X */
X/*
X * Allocate new structure that holds both object-to-world and
X * world-to-object space transformation structures.  It probably
X * should hold pointers to these structures.
X */
XTrans *
XTransCreate(tr, meth)
XTransRef tr;
XTransMethods *meth;
X{
X    Trans *res;
X
X    res = (Trans *)share_malloc(sizeof(Trans));
X    res->tr = tr;
X    res->methods = meth;
X    res->animated = FALSE;
X    res->assoc = (ExprAssoc *)NULL;
X    res->prev = res->next = (Trans *)NULL;
X    MatrixInit(&res->trans);
X    MatrixInit(&res->itrans);
X    return res;
X}
X
Xvoid
XTransFree(trans)
XTrans *trans;
X{
X    if (trans->tr)
X        free((voidstar)trans->tr);
X    free((voidstar)trans);
X}
X
Xvoid
XTransAssoc(trans, ptr, expr)
XTrans *trans;
XFloat *ptr;
XExpr *expr;
X{
X    ExprAssoc *assoc;
X
X    if (expr->timevary) {
X        /*
X         * Gotta store the sucker.
X         */
X        trans->assoc = AssocCreate(ptr, expr, trans->assoc);
X        trans->animated = TRUE;
X    } else {
X        *ptr = expr->value;
X    }
X    fflush(stderr);
X}
X
X/*
X * Allocate new transformation 'matrix'.
X */
XRSMatrix *
XMatrixCreate()
X{
X    RSMatrix *res;
X
X    res = (RSMatrix *)share_malloc(sizeof(RSMatrix));
X    MatrixInit(res);
X    return res;
X}
X
X/*
X * Multiply m1 and m2, copy result into "res".
X */
Xvoid
XMatrixMult(t1, t2, res)
XRSMatrix *t1, *t2, *res;
X{
X    register int i;
X    RSMatrix tmp;
X
X    for (i = 0; i < 3; i++) {
X        tmp.matrix[i][0] = t1->matrix[i][0] * t2->matrix[0][0] +
X                     t1->matrix[i][1] * t2->matrix[1][0] +
X                     t1->matrix[i][2] * t2->matrix[2][0];
X        tmp.matrix[i][1] = t1->matrix[i][0] * t2->matrix[0][1] +
X                     t1->matrix[i][1] * t2->matrix[1][1] +
X                     t1->matrix[i][2] * t2->matrix[2][1];
X        tmp.matrix[i][2] = t1->matrix[i][0] * t2->matrix[0][2] +
X                     t1->matrix[i][1] * t2->matrix[1][2] +
X                     t1->matrix[i][2] * t2->matrix[2][2];
X    }
X
X    tmp.translate.x = t1->translate.x * t2->matrix[0][0] +
X              t1->translate.y * t2->matrix[1][0] +
X              t1->translate.z * t2->matrix[2][0] + t2->translate.x;
X    tmp.translate.y = t1->translate.x * t2->matrix[0][1] +
X              t1->translate.y * t2->matrix[1][1] +
X              t1->translate.z * t2->matrix[2][1] + t2->translate.y;
X    tmp.translate.z = t1->translate.x * t2->matrix[0][2] +
X              t1->translate.y * t2->matrix[1][2] +
X              t1->translate.z * t2->matrix[2][2] + t2->translate.z;
X    MatrixCopy(&tmp, res);
X}
X
X/*
X * Return transformation information to map the "coordinate system"
X * with the given origin, "up" vector, radius, and up axis lengths to
X * one in which the "up" vector is the Z axis and the x/y/up axes
X * have unit length.  This is useful for transforming a general
X * form of a primitive into a canonical, Z-axis aligned, unit size
X * primitive, facilitating intersection testing.
X */
Xvoid
XCoordSysTransform(origin, up, r, len, trans)
XVector *origin, *up;
XFloat r, len;
XTrans *trans;
X{
X    RSMatrix tmp;
X    Vector atmp;
X
X    ScaleMatrix(r, r, len, &trans->trans);
X    if (fabs(up->z) == 1.) {
X        atmp.x = 1.;
X        atmp.y = atmp.z = 0.;
X    } else {
X        atmp.x = up->y;
X        atmp.y = -up->x;
X        atmp.z= 0.;
X    }
X    /*
X     * Might want to make sure that |up->z| is < 1.
X     */
X    RotationMatrix(atmp.x, atmp.y, atmp.z, -acos(up->z), &tmp);
X    MatrixMult(&trans->trans, &tmp, &trans->trans);
X    TranslationMatrix(origin->x, origin->y, origin->z, &tmp);
X    MatrixMult(&trans->trans, &tmp, &trans->trans);
X    MatrixInvert(&trans->trans, &trans->itrans);
X}
X
Xvoid
XTransCopy(from, into)
XTrans *into, *from;
X{
X    MatrixCopy(&from->trans, &into->trans);
X    MatrixCopy(&from->itrans, &into->itrans);
X}
X
Xvoid
XTransInvert(from, into)
XTrans *into, *from;
X{
X    RSMatrix ttmp;
X    /*
X     * In case into == from...
X     */
X    if (from == into) {
X        ttmp = from->trans;
X        into->trans = from->itrans;
X        into->itrans = ttmp;
X    } else {
X        into->trans = from->itrans;
X        into->itrans = from->trans;
X    }
X}
X
X/*
X * Copy a given transformation structure.
X */
Xvoid
XMatrixCopy(from, into)
XRSMatrix *into, *from;
X{
X    into->matrix[0][0] = from->matrix[0][0];
X    into->matrix[0][1] = from->matrix[0][1];
X    into->matrix[0][2] = from->matrix[0][2];
X    into->matrix[1][0] = from->matrix[1][0];
X    into->matrix[1][1] = from->matrix[1][1];
X    into->matrix[1][2] = from->matrix[1][2];
X    into->matrix[2][0] = from->matrix[2][0];
X    into->matrix[2][1] = from->matrix[2][1];
X    into->matrix[2][2] = from->matrix[2][2];
X    into->translate = from->translate;
X}
X
Xvoid
XTransInit(trans)
XTrans *trans;
X{
X    MatrixInit(&trans->trans);
X    MatrixInit(&trans->itrans);
X}
X
Xvoid
XTransCompose(t1, t2, res)
XTrans *t1, *t2, *res;
X{
X    MatrixMult(&t1->trans, &t2->trans, &res->trans);
X    MatrixMult(&t2->itrans, &t1->itrans, &res->itrans);
X}
X
X/*
X * Initialize transformation structure.
X */
Xvoid
XMatrixInit(trans)
XRSMatrix *trans;
X{
X    trans->matrix[0][0] = trans->matrix[1][1] = trans->matrix[2][2] = 1.;
X    trans->matrix[0][1] = trans->matrix[0][2] = trans->matrix[1][0] =
X    trans->matrix[1][2] = trans->matrix[2][0] = trans->matrix[2][1] = 0.;
X    trans->translate.x = trans->translate.y = trans->translate.z = 0.;
X}
X
X/*
X * Calculate inverse of the given transformation structure.
X */
Xvoid
XMatrixInvert(trans, inverse)
XRSMatrix *inverse, *trans;
X{
X    RSMatrix ttmp;
X    int i;
X    Float d;
X    extern int yylineno;
X
X    ttmp.matrix[0][0] = trans->matrix[1][1]*trans->matrix[2][2] -
X                trans->matrix[1][2]*trans->matrix[2][1];
X    ttmp.matrix[1][0] = trans->matrix[1][0]*trans->matrix[2][2] -
X                trans->matrix[1][2]*trans->matrix[2][0];
X    ttmp.matrix[2][0] = trans->matrix[1][0]*trans->matrix[2][1] -
X                trans->matrix[1][1]*trans->matrix[2][0];
X
X    ttmp.matrix[0][1] = trans->matrix[0][1]*trans->matrix[2][2] -
X                trans->matrix[0][2]*trans->matrix[2][1];
X    ttmp.matrix[1][1] = trans->matrix[0][0]*trans->matrix[2][2] -
X                trans->matrix[0][2]*trans->matrix[2][0];
X    ttmp.matrix[2][1] = trans->matrix[0][0]*trans->matrix[2][1] -
X                trans->matrix[0][1]*trans->matrix[2][0];
X
X    ttmp.matrix[0][2] = trans->matrix[0][1]*trans->matrix[1][2] -
X                trans->matrix[0][2]*trans->matrix[1][1];
X    ttmp.matrix[1][2] = trans->matrix[0][0]*trans->matrix[1][2] -
X                trans->matrix[0][2]*trans->matrix[1][0];
X    ttmp.matrix[2][2] = trans->matrix[0][0]*trans->matrix[1][1] -
X                trans->matrix[0][1]*trans->matrix[1][0];
X
X    d = trans->matrix[0][0]*ttmp.matrix[0][0] -
X        trans->matrix[0][1]*ttmp.matrix[1][0] +
X        trans->matrix[0][2]*ttmp.matrix[2][0];
X
X    if (fabs(d) < EPSILON*EPSILON)
X        RLerror(RL_PANIC, "Singular matrix.\n",yylineno);
X
X    ttmp.matrix[0][0] /= d;
X    ttmp.matrix[0][2] /= d;
X    ttmp.matrix[1][1] /= d;
X    ttmp.matrix[2][0] /= d;
X    ttmp.matrix[2][2] /= d;
X
X    d = -d;
X
X    ttmp.matrix[0][1] /= d;
X    ttmp.matrix[1][0] /= d;
X    ttmp.matrix[1][2] /= d;
X    ttmp.matrix[2][1] /= d;
X
X    ttmp.translate.x = -(ttmp.matrix[0][0]*trans->translate.x +
X                 ttmp.matrix[1][0]*trans->translate.y +
X                 ttmp.matrix[2][0]*trans->translate.z);
X    ttmp.translate.y = -(ttmp.matrix[0][1]*trans->translate.x +
X                 ttmp.matrix[1][1]*trans->translate.y +
X                 ttmp.matrix[2][1]*trans->translate.z);
X    ttmp.translate.z = -(ttmp.matrix[0][2]*trans->translate.x +
X                 ttmp.matrix[1][2]*trans->translate.y +
X                 ttmp.matrix[2][2]*trans->translate.z);
X
X    MatrixCopy(&ttmp, inverse);
X}
X
X/*
X * Apply a transformation to a point (translation affects the point).
X */
Xvoid
XPointTransform(vec, trans)
XVector *vec;
XRSMatrix *trans;
X{
X    Vector tmp;
X
X    tmp.x = vec->x * trans->matrix[0][0] + vec->y * trans->matrix[1][0] +
X            vec->z * trans->matrix[2][0] + trans->translate.x;
X    tmp.y = vec->x * trans->matrix[0][1] + vec->y * trans->matrix[1][1] +
X            vec->z * trans->matrix[2][1] + trans->translate.y;
X    tmp.z = vec->x * trans->matrix[0][2] + vec->y * trans->matrix[1][2] +
X            vec->z * trans->matrix[2][2] + trans->translate.z;
X    *vec = tmp;
X}
X
X/*
X * 'c1x' is the X (0th) component of the first column, and so on.
X */
Xvoid
XArbitraryMatrix(c1x, c2x, c3x, c1y, c2y, c3y, c1z, c2z, c3z, tx, ty, tz, trans)
XFloat c1x, c1y, c1z, c2x, c2y, c2z, c3x, c3y, c3z, tx, ty, tz;
XRSMatrix *trans;
X{
X    trans->matrix[0][0] = c1x;
X    trans->matrix[1][0] = c1y;
X    trans->matrix[2][0] = c1z;
X
X    trans->matrix[0][1] = c2x;
X    trans->matrix[1][1] = c2y;
X    trans->matrix[2][1] = c2z;
X
X    trans->matrix[0][2] = c3x;
X    trans->matrix[1][2] = c3y;
X    trans->matrix[2][2] = c3z;
X
X    trans->translate.x = tx;
X    trans->translate.y = ty;
X    trans->translate.z = tz;
X}
X
X/*
X * Apply transformation to a vector (translations have no effect).
X */
Xvoid
XVecTransform(vec, trans)
XVector *vec;
XRSMatrix *trans;
X{
X    Vector tmp;
X
X    tmp.x = vec->x*trans->matrix[0][0] +
X        vec->y*trans->matrix[1][0] + vec->z*trans->matrix[2][0];
X    tmp.y = vec->x*trans->matrix[0][1] +
X        vec->y*trans->matrix[1][1] + vec->z*trans->matrix[2][1];
X    tmp.z = vec->x*trans->matrix[0][2] +
X        vec->y*trans->matrix[1][2] + vec->z*trans->matrix[2][2];
X
X    *vec = tmp;
X}
X
X/*
X * Transform normal -- multiply by the transpose of the given
X * matrix (which is the inverse of the 'desired' transformation).
X */
Xvoid
XNormalTransform(norm, it)
XVector *norm;
XRSMatrix *it;
X{
X    Vector onorm;
X
X    onorm = *norm;
X
X    norm->x = onorm.x*it->matrix[0][0] + onorm.y*it->matrix[0][1] +
X                onorm.z*it->matrix[0][2];
X    norm->y = onorm.x*it->matrix[1][0] + onorm.y*it->matrix[1][1] +
X                onorm.z*it->matrix[1][2];
X    norm->z = onorm.x*it->matrix[2][0] + onorm.y*it->matrix[2][1] +
X                onorm.z*it->matrix[2][2];
X    (void)VecNormalize(norm);
X}
X
X/*
X * Transform "ray" by transforming the origin point and direction vector.
X */
XFloat
XRayTransform(ray, trans)
XRay *ray;
XRSMatrix *trans;
X{
X    PointTransform(&ray->pos, trans);
X    VecTransform(&ray->dir, trans);
X    return VecNormalize(&ray->dir);
X}
X
Xvoid
XTransPropagate(trans)
XTrans *trans;
X{
X    (*trans->methods->propagate)(trans->tr, &trans->trans, &trans->itrans);
X}
X
Xvoid
XTransResolveAssoc(trans)
XTrans *trans;
X{
X    Trans *curtrans;
X    ExprAssoc *curassoc;
X
X    for (curtrans = trans; curtrans; curtrans = curtrans->next) {
X        for (curassoc = curtrans->assoc; curassoc; curassoc = curassoc->next) {
X            *curassoc->lhs = ExprEval(curassoc->expr);
X        }
X        if (curtrans->assoc)
X            TransPropagate(curtrans);
X    }
X}
X
Xvoid
XTransComposeList(list, result)
XTrans *list, *result;
X{
X    TransCopy(list, result);
X    for (list = list->next; list; list = list->next)
X        TransCompose(list, result, result);
X}
END_OF_FILE
if test 10691 -ne `wc -c <'libray/libcommon/transform.c'`; then
    echo shar: \"'libray/libcommon/transform.c'\" unpacked with wrong size!
fi
# end of 'libray/libcommon/transform.c'
fi
if test -f 'libray/libobj/csg.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'libray/libobj/csg.c'\"
else
echo shar: Extracting \"'libray/libobj/csg.c'\" \(10585 characters\)
sed "s/^X//" >'libray/libobj/csg.c' <<'END_OF_FILE'
X/*
X * csg.c
X *
X * Copyright (C) 1991, Rod G. Bogart, Craig E. Kolb
X * All rights reserved.
X *
X * This software may be freely copied, modified, and redistributed
X * provided that this copyright notice is preserved on all copies.
X *
X * You may not distribute this software, in whole or in part, as part of
X * any commercial product without the express consent of the authors.
X *
X * There is no warranty or other guarantee of fitness of this software
X * for any purpose.  It is provided solely "as is".
X *
X * $Id: csg.c,v 4.0 91/07/17 14:37:00 kolb Exp Locker: kolb $
X *
X * $Log:    csg.c,v $
X * Revision 4.0  91/07/17  14:37:00  kolb
X * Initial version.
X *
X */
X#include "geom.h"
X#include "csg.h"
X
X#define csg_set_enter(l, f) ((l)->data[0].enter = (f) + 1)
X
Xstatic Methods *iCsgMethods = NULL;
Xstatic char csgName[] = "csg";
X
Xstatic int    CsgUnionInt(), CsgDifferenceInt(),
X        CsgIntersectInt();
Xstatic void    CsgHitlistCopy(), CsgSetBounds();
X
XCsg *
XCsgCreate(op)
Xint op;
X{
X    Csg *csg;
X
X    csg = (Csg *)share_malloc(sizeof(Csg));
X    csg->operator = op;
X    csg->obj1 = csg->obj2 = (Geom *)NULL;
X
X
X    switch(op) {
X        case CSG_UNION:
X            csg->intmeth = CsgUnionInt;
X            break;
X        case CSG_INTERSECT:
X            csg->intmeth = CsgIntersectInt;
X            break;
X        case CSG_DIFFERENCE:
X            csg->intmeth = CsgDifferenceInt;
X            break;
X        default:
X            RLerror(RL_ABORT, "Unknown csg op type %d?\n",op);
X    }
X    return csg;
X}
X
XMethods *
XCsgMethods()
X{
X    if (iCsgMethods== (Methods *)NULL) {
X        iCsgMethods = MethodsCreate();
X        iCsgMethods->create = (GeomCreateFunc *)CsgCreate;
X        iCsgMethods->convert = CsgConvert;
X        iCsgMethods->methods = CsgMethods;
X        iCsgMethods->name = CsgName;
X        iCsgMethods->intersect = CsgIntersect;
X        iCsgMethods->bounds = CsgBounds;
X        iCsgMethods->checkbounds = FALSE;
X        iCsgMethods->closed = TRUE;
X    }
X    return iCsgMethods;
X}
X
Xchar *
XCsgName()
X{
X    return csgName;
X}
X
Xcsg_intersect_objs(csg, ray, hit1, hit2, mindist, dist1, dist2)
XCsg *csg;
XRay *ray;
XHitList *hit1, *hit2;
XFloat mindist, *dist1, *dist2;
X{
X    int operator;
X
X    hit1->nodes = 0;
X    hit2->nodes = 0;
X    *dist1 = FAR_AWAY;
X    *dist2 = FAR_AWAY;
X    operator = csg->operator;
X
X    if (!intersect(csg->obj1, ray, hit1, mindist, dist1) &&
X        ((operator == CSG_INTERSECT) || (operator == CSG_DIFFERENCE))) {
X        /*
X         * Intersection and Difference cases: if you miss the first
X         * object, you missed the whole thing.
X         */
X        return FALSE;
X    }
X
X    if (!intersect(csg->obj2, ray, hit2, mindist, dist2) &&
X        ((operator == CSG_INTERSECT) ||
X         (hit1->nodes == 0) && (operator == CSG_UNION))) {
X        /*
X         * Intersect case:  if you miss either object, you miss whole
X         * Union case: if you miss both object, you miss whole
X         */
X        return FALSE;
X    }
X
X    return TRUE;
X}
X
Xint
Xcsg_enter_obj(hitp)
XHitList *hitp;
X{
X    if (hitp->data[0].enter)
X        return hitp->data[0].enter - 1;
X
X    return PrimEnter(hitp->data[0].obj, &hitp->data[0].ray,
X            hitp->data[0].mindist, hitp->data[0].dist);
X}
X
Xstatic int
XCsgUnionInt(ray, hit1p, hit2p, dist1, dist2, hitclose, distclose)
XRay *ray;
XHitList *hit1p, *hit2p, **hitclose;
XFloat dist1, dist2, *distclose;
X{
X    Float distnext;
X    HitList hitnext, *hittmp;
X
X    while (TRUE) {
X        if (hit2p->nodes == 0 ||
X            csg_enter_obj(hit2p)) {
X            /* return hit1 */
X            *hitclose = hit1p;
X            *distclose = dist1;
X            csg_set_enter(hit1p, csg_enter_obj(hit1p));
X            return TRUE;
X        } else {
X            distnext = FAR_AWAY;
X            hitnext.nodes = 0;
X            if (!intersect(hit1p->data[hit1p->nodes-1].obj,
X                ray, &hitnext, dist2+EPSILON, &distnext)) {
X                /*
X                 * None of obj1 beyond, return hit2 (leaving)
X                 */
X                *hitclose = hit2p;
X                *distclose = dist2;
X                csg_set_enter(hit2p, FALSE);
X                return TRUE;
X            } else {
X                /*
X                 * Since hit1 is supposed to be the close one,
X                 * swap them and copy hitnext into hit2.
X                      */
X                hittmp = hit1p;
X                hit1p = hit2p;
X                hit2p = hittmp;
X                dist1 = dist2;
X                CsgHitlistCopy(&hitnext, hit2p);
X                dist2 = distnext;
X                /* and continue */
X            }
X        }
X    }
X}
X
Xstatic int
XCsgIntersectInt(ray, hit1p, hit2p, dist1, dist2, hitclose, distclose)
XRay *ray;
XHitList *hit1p, *hit2p, **hitclose;
XFloat dist1, dist2, *distclose;
X{
X    HitList *hittmp, hitnext;
X    Float distnext;
X
X    while (TRUE) {
X        if (!csg_enter_obj(hit2p)) {
X            /* Ray is leaving obj2 */
X            /* Return hit1 info */
X            *hitclose = hit1p;
X            *distclose = dist1;
X            csg_set_enter(hit1p, csg_enter_obj(hit1p));
X            return TRUE;
X        } else {
X            distnext = FAR_AWAY;
X            hitnext.nodes = 0;
X            if (!intersect(hit1p->data[hit1p->nodes-1].obj,
X                ray, &hitnext, dist2+EPSILON, &distnext)) {
X                /*
X                 * None of obj1 beyond, so return miss
X                 */
X                return FALSE;
X            } else {
X                /*
X                 * Since hit1 is supposed to be the
X                 * close one, swap them and copy
X                 * hitnext into hit2.
X                 */
X                hittmp = hit1p;
X                hit1p = hit2p;
X                hit2p = hittmp;
X                dist1 = dist2;
X                CsgHitlistCopy(&hitnext, hit2p);
X                dist2 = distnext;
X                /* and continue */
X            }
X        }
X    }
X}
X
Xstatic int
XCsgDifferenceInt(ray, hit1p, hit2p, dist1, dist2, hitclose, distclose)
XRay *ray;
XHitList *hit1p, *hit2p, **hitclose;
XFloat dist1, dist2, *distclose;
X{
X    Float distnext;
X    HitList hitnext;
X
X    while (TRUE) {
X        if (dist1 < dist2) {
X            if (hit2p->nodes == 0 ||
X                csg_enter_obj(hit2p)) {
X                /* return hit1 */
X                *hitclose = hit1p;
X                *distclose = dist1;
X                csg_set_enter(hit1p, csg_enter_obj(hit1p));
X                return TRUE;
X            } else {
X                distnext = FAR_AWAY;
X                hitnext.nodes = 0;
X                if (!intersect(hit1p->data[hit1p->nodes-1].obj,
X                    ray, &hitnext, dist2+EPSILON, &distnext)) {
X                    /*
X                     * None of obj1 beyond, so
X                     * return miss
X                     */
X                    return FALSE;
X                } else {
X                    dist1 = distnext;
X                    CsgHitlistCopy(&hitnext, hit1p);
X                    /* and continue */
X                }
X            }
X        } else { /* dist1 <= dist2 */
X            if (hit1p->nodes == 0) {
X                /* return a miss */
X                return FALSE;
X            }
X            if (!csg_enter_obj(hit1p)) {
X                /*
X                 * return hit2, but invert hit2
X                 * Enter/Leave flag
X                 */
X                *hitclose = hit2p;
X                *distclose = dist2;
X                csg_set_enter(hit2p, !csg_enter_obj(hit2p));
X                return TRUE;
X            } else {
X                distnext = FAR_AWAY;
X                hitnext.nodes = 0;
X                if (!intersect(hit2p->data[hit2p->nodes-1].obj,
X                    ray, &hitnext, dist1+EPSILON, &distnext)) {
X                    /*
X                     * None of obj2 beyond, so
X                     * return hit1
X                     */
X                    *hitclose = hit1p;
X                    *distclose = dist1;
X                    /* we know we're entering obj1 */
X                    csg_set_enter(hit1p, TRUE);
X                    return TRUE;
X                } else {
X                    dist2 = distnext;
X                    CsgHitlistCopy(&hitnext, hit2p);
X                    /* and continue */
X                }
X            }
X        }
X    }
X}
X
Xint
XCsgIntersect(csg, ray, hitlist, mindist, maxdist)
XCsg *csg;
XRay *ray;
XHitList *hitlist;
XFloat mindist, *maxdist;
X{
X    Float dist1, dist2, disttmp, distclose;
X    HitList hit1, hit2, *hit1p, *hit2p, *hitclose;
X
X    hit1p = &hit1;
X    hit2p = &hit2;
X    if (!csg_intersect_objs(csg, ray, hit1p, hit2p, mindist,
X        &dist1, &dist2)) {
X        /* missed the csg object */
X        return FALSE;
X    }
X
X    if ((dist1 > dist2) &&
X        (csg->operator == CSG_UNION || csg->operator == CSG_INTERSECT)) {
X        /* swap so 1 is closest (except in difference case) */
X        disttmp = dist2;
X        dist2 = dist1;
X        dist1 = disttmp;
X        hit1p = &hit2;
X        hit2p = &hit1;
X    }
X
X    /*
X     * Call appropriate intersection method.  If FALSE is return,
X     * no hit of any kind was found.
X     */
X    if (!(*csg->intmeth)(ray, hit1p, hit2p, dist1, dist2,
X        &hitclose, &distclose))
X        return FALSE;
X
X    /*
X     * At this time, the closest hit is in hitclose and
X     * distclose.
X     */
X    if (distclose < mindist || distclose > *maxdist)
X        return FALSE;
X
X    CsgHitlistCopy(hitclose, hitlist);
X    *maxdist = distclose;
X    return TRUE;
X}
X
Xstatic void
XCsgHitlistCopy(from, to)
XHitList *from, *to;
X{
X    int i;
X
X    to->nodes = from->nodes;
X    for (i = 0; i < from->nodes; i++)
X        to->data[i] = from->data[i];
X}
X
Xstatic void
XCsgSetBounds(csg, bounds)
XCsg *csg;
XFloat bounds[2][3];
X{
X    GeomComputeBounds(csg->obj1);
X    GeomComputeBounds(csg->obj2);
X
X    switch (csg->operator) {
X    case CSG_UNION:
X        bounds[LOW][X] = min(csg->obj1->bounds[LOW][X], csg->obj2->bounds[LOW][X]);
X        bounds[HIGH][X] = max(csg->obj1->bounds[HIGH][X], csg->obj2->bounds[HIGH][X]);
X        bounds[LOW][Y] = min(csg->obj1->bounds[LOW][Y], csg->obj2->bounds[LOW][Y]);
X        bounds[HIGH][Y] = max(csg->obj1->bounds[HIGH][Y], csg->obj2->bounds[HIGH][Y]);
X        bounds[LOW][Z] = min(csg->obj1->bounds[LOW][Z], csg->obj2->bounds[LOW][Z]);
X        bounds[HIGH][Z] = max(csg->obj1->bounds[HIGH][Z], csg->obj2->bounds[HIGH][Z]);
X        break;
X    case CSG_INTERSECT:
X        bounds[LOW][X] = max(csg->obj1->bounds[LOW][X], csg->obj2->bounds[LOW][X]);
X        bounds[HIGH][X] = min(csg->obj1->bounds[HIGH][X], csg->obj2->bounds[HIGH][X]);
X        bounds[LOW][Y] = max(csg->obj1->bounds[LOW][Y], csg->obj2->bounds[LOW][Y]);
X        bounds[HIGH][Y] = min(csg->obj1->bounds[HIGH][Y], csg->obj2->bounds[HIGH][Y]);
X        bounds[LOW][Z] = max(csg->obj1->bounds[LOW][Z], csg->obj2->bounds[LOW][Z]);
X        bounds[HIGH][Z] = min(csg->obj1->bounds[HIGH][Z], csg->obj2->bounds[HIGH][Z]);
X        break;
X    case CSG_DIFFERENCE:
X        bounds[LOW][X] = csg->obj1->bounds[LOW][X];
X        bounds[HIGH][X] = csg->obj1->bounds[HIGH][X];
X        bounds[LOW][Y] = csg->obj1->bounds[LOW][Y];
X        bounds[HIGH][Y] = csg->obj1->bounds[HIGH][Y];
X        bounds[LOW][Z] = csg->obj1->bounds[LOW][Z];
X        bounds[HIGH][Z] = csg->obj1->bounds[HIGH][Z];
X        break;
X    default:
X        RLerror(RL_ABORT, "Unknown csg operator type %d?\n",
X            csg->operator);
X    }
X}
X
X/*
X * Return index of hitlist node closest to the leaf and not below any
X * CSG object.
X */
Xint
XFirstCSGGeom(hitlist)
XHitList *hitlist;
X{
X    int i;
X
X    /*
X     * UUUUGLY -- detect if obj is a CsgGeom by comparing
X     * methods with iCsgMethods.
X     */
X    for (i = hitlist->nodes -1; i; i--)
X        if (hitlist->data[i].obj->methods == iCsgMethods)
X            return i;
X    return 0;
X}
X
Xvoid
XCsgBounds(csg, bounds)
XCsg *csg;
XFloat bounds[2][3];
X{
X    CsgSetBounds(csg, csg->bounds);
X    BoundsCopy(csg->bounds, bounds);
X}
X
Xint
XCsgConvert(csg, list)
XCsg *csg;
XGeom *list;
X{
X    static int OpenAdvised = FALSE;
X    /*
X     * Currently, this only handles two objects.
X     * Will be fixed in the future.
X     * No really we promise.
X     */
X    if (!list || !list->next) {
X        RLerror(RL_WARN, "CSG needs at least two objects.\n");
X        return 0;
X    }
X    if (list->next->next) {
X        RLerror(RL_WARN, "Currently, CSG only handles two objects.\n");
X        return 0;
X    }
X    /*
X     * Things are put into lists backwards....
X     */
X    csg->obj2 = list;
X    csg->obj1 = list->next;
X    if ((!csg->obj1->methods->closed || !csg->obj2->methods->closed) &&
X        !OpenAdvised) {
X        RLerror(RL_ADVISE,
X            "Performing CSG with non-closed object(s).\n");
X        OpenAdvised = TRUE;
X    }
X    return csg->obj1->prims + csg->obj2->prims;
X}
X
Xvoid
XCsgMethodRegister(meth)
XUserMethodType meth;
X{
X    if (iCsgMethods)
X        iCsgMethods->user = meth;
X}
END_OF_FILE
if test 10585 -ne `wc -c <'libray/libobj/csg.c'`; then
    echo shar: \"'libray/libobj/csg.c'\" unpacked with wrong size!
fi
# end of 'libray/libobj/csg.c'
fi
if test -f 'libshade/shade.c' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'libshade/shade.c'\"
else
echo shar: Extracting \"'libshade/shade.c'\" \(10451 characters\)
sed "s/^X//" >'libshade/shade.c' <<'END_OF_FILE'
X/*
X * shade.c
X *
X * Copyright (C) 1989, 1991, Craig E. Kolb
X * All rights reserved.
X *
X * This software may be freely copied, modified, and redistributed
X * provided that this copyright notice is preserved on all copies.
X *
X * You may not distribute this software, in whole or in part, as part of
X * any commercial product without the express consent of the authors.
X *
X * There is no warranty or other guarantee of fitness of this software
X * for any purpose.  It is provided solely "as is".
X *
X * $Id: shade.c,v 4.0 91/07/17 14:47:36 kolb Exp Locker: kolb $
X *
X * $Log:    shade.c,v $
X * Revision 4.0  91/07/17  14:47:36  kolb
X * Initial version.
X *
X */
X#include "rayshade.h"
X#include "libtext/texture.h"
X#include "libsurf/surface.h"
X#include "liblight/light.h"
X#include "libsurf/atmosphere.h"
X#include "options.h"
X#include "stats.h"
X
XMedium    TopMedium;
XAtmosphere *AtmosEffects;
X
Xstatic void shade(), LightRay(), Lighting(), ReflectRay();
Xstatic int TransmitRay();
X
X/*
X * Calculate color of ray.
X */
Xvoid
XShadeRay(hitlist, ray, dist, back, color, contrib)
XHitList *hitlist;        /* Information about point of intersection. */
XRay *ray;            /* Direction and origin of ray. */
XFloat dist;            /* Distance from origin of intersection. */
XColor    *back,            /* "Background" color */
X    *color,            /* Color to assign current ray. */
X    *contrib;        /* Contribution of this ray to final color */
X{
X    Vector norm, gnorm, pos; /* surface normal, point of intersection */
X    Surface surf, *stmp;    /* surface properties */
X    int enter, smooth;    /* entering ?, gnorm != snorm ?*/
X
X    if (hitlist->nodes == 0) {
X        /*
X         * No valid intersection.  Set distance for atmospheric
X         * effects and set color of ray to background.
X         */
X        *color = *back;
X        VecAddScaled(ray->pos, FAR_AWAY, ray->dir, &pos);
X        if (!ray->media && AtmosEffects)
X            Atmospherics(AtmosEffects, ray, FAR_AWAY, &pos, color);
X        return;
X    }
X
X    /*
X     * Compute normal, surface properties, etc.
X     */
X    stmp = GetShadingSurf(hitlist);
X    surf = *stmp;
X    enter = ComputeSurfProps(hitlist, ray, &pos, &norm, &gnorm, &surf,
X            &smooth);
X    Stats.HitRays++;
X
X    /*
X     * Calculate ray color.
X     */
X    shade(&pos, ray, &norm, &gnorm, smooth, enter, &surf, back, color,
X            contrib);
X    if (!ray->media && AtmosEffects)
X        Atmospherics(AtmosEffects, ray, dist, &pos, color);
X}
X
X/*
X * Perform lighting calculations based on surface normal & other properties,
X * incident ray direction and position, and light source properties.
X * Spawn any necessary reflected and transmitted rays.
X */
Xstatic void
Xshade(pos, ray, nrm, gnrm, smooth, enter, surf, back, color, contrib)
XVector *pos, *nrm, *gnrm;    /* hit pos, shade normal, geo normal */
Xint smooth;            /* true if shading norm and geo norm differ */
Xint enter;            /* TRUE if entering surface */
XRay *ray;            /* indicent ray */
XSurface *surf;            /* properties of hit surface */
XColor *back, *color;        /* background color, computed color */
XColor *contrib;            /* contribution to final pixel value */
X{
X    Float    k;        /* -ray . normal */
X    Color    newcontrib;
X    Vector    refl;        /* reflected direction */
X    Color    reflectivity,    /* effective surface reflectivity */
X        intens;        /* reflected/transmitted intensity */
X    Light *lp;        /* current light source */
X    extern Light *Lights;    /* list of defined sources */
X
X    /*
X     * Ambient color is always included.
X     */
X    ColorMultiply(surf->amb, Options.ambient, color);
X
X    /*
X     * Calculate direction of reflected ray.
X     */
X    k = -dotp(&ray->dir, nrm);
X    VecAddScaled(ray->dir, 2.*k, *nrm, &refl);
X
X    /*
X     * Calculate intensity contributed by each light source.
X     */
X    for (lp = Lights; lp; lp = lp->next)
X        LightRay(lp, pos, nrm, gnrm, smooth, &refl, surf,
X                ray->depth, ray->sample, ray->time, color);
X
X    if (ray->depth >= Options.maxdepth)
X        /*
X         * Don't spawn any transmitted/reflected rays.
X         */
X        return;
X    /*
X     * Specular transmission (refraction).
X     */
X    ColorScale(surf->reflect, surf->spec, &reflectivity);
X
X    if (surf->transp > EPSILON) {
X        ColorScale(surf->transp, surf->body, &intens);
X        ColorMultiply(intens, *contrib, &newcontrib);
X        if (newcontrib.r > Options.cutoff.r ||
X            newcontrib.g > Options.cutoff.g ||
X            newcontrib.b > Options.cutoff.b)
X            /*
X             * Transmit ray.  If TIR occurs, add transmitted
X             * component to reflected component.  Kinda strange, but...
X             */
X            if (TransmitRay(ray, pos, nrm, k, surf->index,
X                surf->statten, enter, back, &newcontrib, &intens, color))
X                ColorAdd(reflectivity, intens, &reflectivity);
X    }
X
X    if (reflectivity.r > EPSILON ||
X        reflectivity.g > EPSILON ||
X        reflectivity.b > EPSILON) {
X        ColorMultiply(reflectivity, *contrib, &newcontrib);
X        if (newcontrib.r > Options.cutoff.r ||
X            newcontrib.g > Options.cutoff.g ||
X            newcontrib.b > Options.cutoff.b)
X            ReflectRay(ray, pos, &refl, back, &reflectivity,
X                &newcontrib, color);
X    }
X}
X
X/*
X * Lighting calculations
X */
Xstatic void
XLightRay(lp, pos, norm, gnorm, smooth, reflect, surf, depth, samp, time, color)
XLight *lp;            /* Light source */
XVector *pos, *norm, *gnorm;    /* hit pos, shade norm, geo norm */
Xint smooth;            /* true if shade and geo norm differ */
XVector *reflect;        /* reflection direction */
XSurface *surf;            /* surface characteristics */
Xint depth, samp;        /* ray depth, sample # */
XFloat time;
XColor *color;            /* resulting color */
X{
X    Color lcolor;
X    Ray newray;
X    Float costheta, cosalpha, dist;
X
X    newray.pos = *pos;
X    newray.depth = depth;
X    newray.sample = samp;
X    newray.time = time;
X    newray.media = (Medium *)NULL;
X
X    LightDirection(lp, pos, &newray.dir, &dist);
X
X    costheta = dotp(&newray.dir, norm);
X
X    if (smooth) {
X        cosalpha = dotp(&newray.dir, gnorm);
X        /*
X         * If shading normal indicates self-shadowing
X         * and geom normal indicates no self-shadowing,
X         * trust the geom normal.
X         */
X        if (costheta <= 0. && cosalpha > 0.)
X            costheta = cosalpha;
X        /*
X         * If geom normal indicates self-shadowing and
X         * geom normal doesn't, then have to do something
X         * clever ala Snyder & Barr.
X         */
X    }
X
X    if (costheta <= 0.) {
X        /*
X         * Light source is on opposite side of surface,
X         * hence light must be transmitted through...
X         */
X        if (surf->translucency < EPSILON)
X            return;
X        if (!LightIntens(lp, &newray, dist,
X            (int)surf->noshadow, &lcolor))
X            return;
X        cosalpha = -dotp(reflect, &newray.dir);
X        Lighting(-costheta, cosalpha, &lcolor, &surf->translu,
X                &surf->body, surf->stexp, color);
X        ColorScale(surf->translucency, *color, color);
X    } else {
X        if (!LightIntens(lp, &newray, dist,
X            (int)surf->noshadow, &lcolor))
X            return;  /* prim is in shadow w.r.t light source */
X
X        cosalpha = dotp(reflect, &newray.dir);
X        Lighting(costheta, cosalpha, &lcolor, &surf->diff,
X                &surf->spec, surf->srexp, color);
X    }
X}
X
X/*
X * Compute shading function (diffuse reflection and specular highlight)
X *
X * This function *adds* the computed color to "color".
X */
Xstatic void
XLighting(costheta, cosalpha, lcolor, diff, spec, coef, color)
XFloat costheta, cosalpha, coef;
XColor *diff, *spec, *color, *lcolor;
X{
X    Float intens;
X
X    /*
X     * Diffuse reflection.
X     * Falls off as the cosine of the angle between
X     * the normal and the ray to the light (costheta).
X     */
X    color->r += diff->r * costheta * lcolor->r;
X    color->g += diff->g * costheta * lcolor->g;
X    color->b += diff->b * costheta * lcolor->b;
X    /*
X     * Specularly reflected highlights.
X     * Fall off as the cosine of the angle
X     * between the reflected ray and the ray to the light source.
X     */
X    if (coef < EPSILON || cosalpha <= 0.)
X        return;
X    /*
X     * Specular highlight = cosine of the angle raised to the
X     * appropriate power.
X     */
X    intens = pow(cosalpha, coef);
X    color->r += spec->r * intens * lcolor->r;
X    color->g += spec->g * intens * lcolor->g;
X    color->b += spec->b * intens * lcolor->b;
X}
X
X/*
X * Spawn a transmitted ray.  Returns TRUE if total internal reflection
X * occurs, FALSE otherwise.
X */
Xstatic int
XTransmitRay(ray, pos, norm, k, index, statten, enter, back, contrib, intens, color)
XRay *ray;
XVector *pos, *norm;
XFloat k, index, statten;
Xint enter;
XColor *back, *contrib, *intens, *color;
X{
X    int total_int_refl = FALSE;
X    Ray NewRay;
X    Float dist;
X    Color newcol;
X    HitList hittmp;        /* Geom intersection record */
X
X    NewRay.pos = *pos;        /* Origin == hit point */
X    NewRay.media = ray->media;    /* Media == old media */
X    NewRay.sample = ray->sample;
X    NewRay.time = ray->time;
X    NewRay.depth = ray->depth + 1;
X
X    if (enter) {
X        /*
X         * Entering surface.
X         */
X        if (Refract(&NewRay.dir,
X            NewRay.media ? NewRay.media->index :
X            TopMedium.index, index, &ray->dir, norm, k)) {
X            total_int_refl = TRUE;
X        } else {
X            /*
X             * Push information for new medium.
X             */
X            NewRay.media = MediumPush(index, statten, NewRay.media);
X        }
X    } else {
X        /*
X         * Exiting surface
X         * Pop medium from stack.
X         */
X        if (NewRay.media != (Medium *)0)
X            NewRay.media = NewRay.media->next;
X        if (Refract(&NewRay.dir, index,
X            NewRay.media ? NewRay.media->index :
X            TopMedium.index, &ray->dir, norm, k)) {
X            total_int_refl = TRUE;
X        }
X    }
X
X    /*
X     * At this point, NewRay.media is the medium into which
X     * the new ray is entering.
X     */
X
X    if (!total_int_refl) {
X        Stats.RefractRays++;
X        hittmp.nodes = 0;
X        dist = FAR_AWAY;
X        TraceRay(&NewRay, &hittmp, EPSILON, &dist);
X        ShadeRay(&hittmp, &NewRay, dist, back, &newcol, contrib);
X        ColorMultiply(newcol, *intens, &newcol);
X        /*
X         * Attenuate transmitted color.  Note that
X         * if the transmitted ray hit nothing, we still
X         * perform this computation, as it's possible
X         * that 'air' has a non-unit statten.
X         */
X        statten = NewRay.media ? NewRay.media->statten :
X            TopMedium.statten;
X        if (statten != 1.0) {
X            statten = pow(statten, dist);
X            ColorScale(statten, newcol, &newcol);
X        }
X        ColorAdd(*color, newcol, color);
X        /* Free pushed medium */
X        if (enter)
X            free((voidstar)NewRay.media);
X    }
X
X    return total_int_refl;
X}
X
Xstatic void
XReflectRay(ray, pos, dir, back, intens, contrib, color)
XRay *ray;
XVector *pos, *dir;
XColor *back, *intens, *contrib, *color;
X{
X    Ray NewRay;
X    HitList hittmp;        /* Geom intersection record */
X    Color newcol;
X    Float dist;
X
X    NewRay.pos = *pos;        /* Origin == hit point */
X    NewRay.dir = *dir;        /* Direction == reflection */
X    NewRay.media = ray->media;    /* Medium == old medium */
X    NewRay.sample = ray->sample;
X    NewRay.time = ray->time;
X    NewRay.depth = ray->depth + 1;
X    Stats.ReflectRays++;
X    hittmp.nodes = 0;
X    dist = FAR_AWAY;
X    (void)TraceRay(&NewRay, &hittmp, EPSILON, &dist);
X    ShadeRay(&hittmp, &NewRay, dist, back, &newcol, contrib);
X    ColorMultiply(newcol, *intens, &newcol);
X    ColorAdd(*color, newcol, color);
X}
END_OF_FILE
if test 10451 -ne `wc -c <'libshade/shade.c'`; then
    echo shar: \"'libshade/shade.c'\" unpacked with wrong size!
fi
# end of 'libshade/shade.c'
fi
echo shar: End of archive 13 \(of 19\).
cp /dev/null ark13isdone
MISSING=""
for I in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 ; do
    if test ! -f ark${I}isdone ; then
    MISSING="${MISSING} ${I}"
    fi
done
if test "${MISSING}" = "" ; then
    echo You have unpacked all 19 archives.
    rm -f ark[1-9]isdone ark[1-9][0-9]isdone
else
    echo You still need to unpack the following archives:
    echo "        " ${MISSING}
fi
##  End of shell archive.
exit 0

exit 0 # Just in case...