color scalar_volume_texture(vector * hit, texture * tex, ray * ry) {
color col, col2;
box * bx;
flt a, tx1, tx2, ty1, ty2, tz1, tz2;
flt tnear, tfar;
flt t, tdist, dt, sum, tt;
vector pnt, bln;
scalarvol * vol;
flt scalar, transval;
int x, y, z;
unsigned char * ptr;
bx=(box *) tex->obj;
vol=(scalarvol *)bx->tex->img;
col.r=0.0;
col.g=0.0;
col.b=0.0;
tnear= -FHUGE;
tfar= FHUGE;
if (ry->d.x == 0.0) {
if ((ry->o.x < bx->min.x) || (ry->o.x > bx->max.x)) return col;
}
else {
tx1 = (bx->min.x - ry->o.x) / ry->d.x;
tx2 = (bx->max.x - ry->o.x) / ry->d.x;
if (tx1 > tx2) { a=tx1; tx1=tx2; tx2=a; }
if (tx1 > tnear) tnear=tx1;
if (tx2 < tfar) tfar=tx2;
}
if (tnear > tfar) return col;
if (tfar < 0.0) return col;
if (ry->d.y == 0.0) {
if ((ry->o.y < bx->min.y) || (ry->o.y > bx->max.y)) return col;
}
else {
ty1 = (bx->min.y - ry->o.y) / ry->d.y;
ty2 = (bx->max.y - ry->o.y) / ry->d.y;
if (ty1 > ty2) { a=ty1; ty1=ty2; ty2=a; }
if (ty1 > tnear) tnear=ty1;
if (ty2 < tfar) tfar=ty2;
}
if (tnear > tfar) return col;
if (tfar < 0.0) return col;
if (ry->d.z == 0.0) {
if ((ry->o.z < bx->min.z) || (ry->o.z > bx->max.z)) return col;
}
else {
tz1 = (bx->min.z - ry->o.z) / ry->d.z;
tz2 = (bx->max.z - ry->o.z) / ry->d.z;
if (tz1 > tz2) { a=tz1; tz1=tz2; tz2=a; }
if (tz1 > tnear) tnear=tz1;
if (tz2 < tfar) tfar=tz2;
}
if (tnear > tfar) return col;
if (tfar < 0.0) return col;
if (tnear < 0.0) tnear=0.0;
tdist=sqrt((flt) (vol->xres*vol->xres + vol->yres*vol->yres + vol->zres*vol->zres));
tt = (vol->opacity / tdist);
bln.x=fabs(bx->min.x - bx->max.x);
bln.y=fabs(bx->min.y - bx->max.y);
bln.z=fabs(bx->min.z - bx->max.z);
dt=sqrt(bln.x*bln.x + bln.y*bln.y + bln.z*bln.z) / tdist;
sum=0.0;
/* move the volume residency check out of loop.. */
if (!vol->loaded) {
LoadVol(vol);
vol->loaded=1;
}
for (t=tnear; t<=tfar; t+=dt) {
pnt.x=((ry->o.x + (ry->d.x * t)) - bx->min.x) / bln.x;
pnt.y=((ry->o.y + (ry->d.y * t)) - bx->min.y) / bln.y;
pnt.z=((ry->o.z + (ry->d.z * t)) - bx->min.z) / bln.z;
x=(int) ((vol->xres - 1.5) * pnt.x + 0.5);
y=(int) ((vol->yres - 1.5) * pnt.y + 0.5);
z=(int) ((vol->zres - 1.5) * pnt.z + 0.5);
ptr = vol->data + ((vol->xres * vol->yres * z) + (vol->xres * y) + x);
scalar = (flt) ((flt) 1.0 * ((int) ptr[0])) / 255.0;
sum += tt * scalar;
transval = tt * scalar;
col2 = VoxelColor(scalar);
if (sum < 1.0) {
col.r += transval * col2.r;
col.g += transval * col2.g;
col.b += transval * col2.b;
if (sum < 0.0) sum=0.0;
}
else {
sum=1.0;
}
}
if (sum < 1.0) { /* spawn transmission rays / refraction */
color transcol;
transcol = shade_transmission(ry, hit, 1.0 - sum);
col.r += transcol.r; /* add the transmitted ray */
col.g += transcol.g; /* to the diffuse and */
col.b += transcol.b; /* transmission total.. */
}
return col;
}
color shader(ray * incident) {
color col, diffuse, phongcol;
vector N, L, hit;
ray shadowray;
flt inten, t, Llen;
object * obj;
int numints, i;
point_light * li;
numints=closest_intersection(&t, &obj, incident->intstruct);
/* find the number of intersections */
/* and return the closest one. */
if (numints < 1) {
/* if there weren't any object intersections then return the */
/* background color for the pixel color. */
return incident->scene->background;
}
if (obj->tex->islight) { /* if the current object is a light, then we */
return obj->tex->col; /* will only use the objects ambient color */
}
RAYPNT(hit, (*incident), t) /* find the point of intersection from t */
obj->methods->normal(obj, &hit, incident, &N); /* find the surface normal */
/* execute the object's texture function */
col = obj->tex->texfunc(&hit, obj->tex, incident);
diffuse.r = 0.0;
diffuse.g = 0.0;
diffuse.b = 0.0;
phongcol = diffuse;
if ((obj->tex->diffuse > 0.0) || (obj->tex->phong > 0.0)) {
for (i=0; i<numlights; i++) { /* loop for light contributions */
li=lightlist[i]; /* set li=to the current light */
VSUB(li->ctr, hit, L) /* find the light vector */
/* calculate the distance to the light from the hit point */
Llen = sqrt(L.x*L.x + L.y*L.y + L.z*L.z) + EPSILON;
L.x /= Llen; /* normalize the light direction vector */
L.y /= Llen;
L.z /= Llen;
VDOT(inten, N, L) /* light intensity */
/* add in diffuse lighting for this light if we're facing it */
if (inten > 0.0) {
/* test for a shadow */
shadowray.intstruct = incident->intstruct;
shadowray.flags = RT_RAY_SHADOW | RT_RAY_BOUNDED;
incident->serial++;
shadowray.serial = incident->serial;
shadowray.mbox = incident->mbox;
shadowray.o = hit;
shadowray.d = L;
shadowray.maxdist = Llen;
shadowray.s = hit;
shadowray.e = li->ctr;
shadowray.scene = incident->scene;
reset_intersection(incident->intstruct);
intersect_objects(&shadowray);
if (!shadow_intersection(incident->intstruct, Llen)) {
/* XXX now that opacity is in the code, have to be more careful */
ColorAddS(&diffuse, &li->tex->col, inten);
/* phong type specular highlights */
if (obj->tex->phong > 0.0) {
flt phongval;
phongval = shade_phong(incident, &hit, &N, &L, obj->tex->phongexp);
if (obj->tex->phongtype)
ColorAddS(&phongcol, &col, phongval);
else
ColorAddS(&phongcol, &(li->tex->col), phongval);
}
}
}
}
}
ColorScale(&diffuse, obj->tex->diffuse);
col.r *= (diffuse.r + obj->tex->ambient); /* do a product of the */
col.g *= (diffuse.g + obj->tex->ambient); /* diffuse intensity with */
col.b *= (diffuse.b + obj->tex->ambient); /* object color + ambient */
if (obj->tex->phong > 0.0) {
ColorAccum(&col, &phongcol);
}
/* spawn reflection rays if necessary */
/* note: this will overwrite the old intersection list */
if (obj->tex->specular > 0.0) {
color specol;
specol = shade_reflection(incident, &hit, &N, obj->tex->specular);
ColorAccum(&col, &specol);
}
/* spawn transmission rays / refraction */
/* note: this will overwrite the old intersection list */
if (obj->tex->opacity < 1.0) {
color transcol;
transcol = shade_transmission(incident, &hit, 1.0 - obj->tex->opacity);
ColorAccum(&col, &transcol);
}
return col; /* return the color of the shaded pixel... */
}
