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/*
* extvol.c - Volume rendering helper routines etc.
*
* $Id: extvol.c,v 1.30 2012/10/17 04:25:57 johns Exp $
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define TACHYON_INTERNAL 1
#include "tachyon.h"
#include "macros.h"
#include "vector.h"
#include "parallel.h"
#include "threads.h"
#include "box.h"
#include "extvol.h"
#include "trace.h"
#include "sphere.h"
#include "light.h"
#include "shade.h"
int extvol_bbox(void * obj, vector * min, vector * max) {
box * b = (box *) obj;
*min = b->min;
*max = b->max;
return 1;
}
static object_methods extvol_methods = {
(void (*)(const void *, void *))(box_intersect),
(void (*)(const void *, const void *, const void *, void *))(box_normal),
extvol_bbox,
free
};
extvol * newextvol(void * voidtex, vector min, vector max,
int samples, flt (* evaluator)(flt, flt, flt)) {
extvol * xvol;
standard_texture * tex, * xvoltex;
tex = (standard_texture *) voidtex;
xvol = (extvol *) malloc(sizeof(extvol));
memset(xvol, 0, sizeof(extvol));
xvol->methods = &extvol_methods;
xvol->min=min;
xvol->max=max;
xvol->evaluator = evaluator;
xvol->ambient = tex->ambient;
xvol->diffuse = tex->diffuse;
xvol->opacity = tex->opacity;
xvol->samples = samples;
xvoltex = malloc(sizeof(standard_texture));
memset(xvoltex, 0, sizeof(standard_texture));
xvoltex->ctr.x = 0.0;
xvoltex->ctr.y = 0.0;
xvoltex->ctr.z = 0.0;
xvoltex->rot = xvoltex->ctr;
xvoltex->scale = xvoltex->ctr;
xvoltex->uaxs = xvoltex->ctr;
xvoltex->vaxs = xvoltex->ctr;
xvoltex->flags = RT_TEXTURE_NOFLAGS;
xvoltex->col=tex->col;
xvoltex->ambient=1.0;
xvoltex->diffuse=0.0;
xvoltex->specular=0.0;
xvoltex->opacity=1.0;
xvoltex->img=NULL;
xvoltex->texfunc=(color(*)(const void *, const void *, void *))(ext_volume_texture);
xvoltex->obj = (void *) xvol; /* XXX hack! */
xvol->tex = (texture *) xvoltex;
return xvol;
}
color ExtVoxelColor(flt scalar) {
color col;
if (scalar > 1.0)
scalar = 1.0;
if (scalar < 0.0)
scalar = 0.0;
if (scalar < 0.5) {
col.g = 0.0;
}
else {
col.g = (scalar - 0.5) * 2.0;
}
col.r = scalar;
col.b = 1.0 - (scalar / 2.0);
return col;
}
color ext_volume_texture(const vector * hit, const texture * tx, ray * ry) {
color col, col2;
box * bx;
extvol * xvol;
flt a, tx1, tx2, ty1, ty2, tz1, tz2;
flt tnear, tfar;
flt t, tdist, dt, ddt, sum, tt;
vector pnt, bln;
flt scalar, transval;
point_light * li;
color diffint;
vector N, L;
flt inten;
standard_texture * tex = (standard_texture *) tx;
bx = (box *) tex->obj;
xvol = (extvol *) tex->obj;
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 = xvol->samples;
tt = (xvol->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 = 1.0 / tdist;
sum = 0.0;
/* Accumulate color as the ray passes through the voxels */
for (t=tnear; t<=tfar; t+=dt) {
if (sum < 1.0) {
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;
/* call external evaluator assume 0.0 -> 1.0 range.. */
scalar = xvol->evaluator(pnt.x, pnt.y, pnt.z);
transval = tt * scalar;
sum += transval;
col2 = ExtVoxelColor(scalar);
col.r += transval * col2.r * xvol->ambient;
col.g += transval * col2.g * xvol->ambient;
col.b += transval * col2.b * xvol->ambient;
ddt = dt;
/* Add in diffuse shaded light sources (no shadows) */
if (xvol->diffuse > 0.0) {
/* Calculate the Volume gradient at the voxel */
N.x = (xvol->evaluator(pnt.x - ddt, pnt.y, pnt.z) -
xvol->evaluator(pnt.x + ddt, pnt.y, pnt.z)) * 8.0 * tt;
N.y = (xvol->evaluator(pnt.x, pnt.y - ddt, pnt.z) -
xvol->evaluator(pnt.x, pnt.y + ddt, pnt.z)) * 8.0 * tt;
N.z = (xvol->evaluator(pnt.x, pnt.y, pnt.z - ddt) -
xvol->evaluator(pnt.x, pnt.y, pnt.z + ddt)) * 8.0 * tt;
/* only light surfaces with enough of a normal.. */
if ((N.x*N.x + N.y*N.y + N.z*N.z) > 0.0) {
list * cur;
diffint.r = 0.0;
diffint.g = 0.0;
diffint.b = 0.0;
/* add the contribution of each of the lights.. */
cur = ry->scene->lightlist;
while (cur != NULL) { /* loop for light contributions */
li=(point_light *) cur->item; /* set li=to the current light */
VSUB(li->ctr, (*hit), L)
VNorm(&L);
VDOT(inten, N, L)
/* only add light if its from the front of the surface */
/* could add back-lighting if we wanted to later.. */
if (inten > 0.0) {
standard_texture * litex = (standard_texture *) li->tex;
diffint.r += inten * litex->col.r;
diffint.g += inten * litex->col.g;
diffint.b += inten * litex->col.b;
}
cur = cur->next;
}
col.r += col2.r * diffint.r * xvol->diffuse;
col.g += col2.g * diffint.g * xvol->diffuse;
col.b += col2.b * diffint.b * xvol->diffuse;
}
}
}
else {
sum=1.0;
}
}
/* Add in transmitted ray from outside environment */
if (sum < 1.0) { /* spawn transmission rays / refraction */
color transcol;
shadedata shadevars;
shadevars.hit=*hit;
/* XXX this ought to be done in shade.c rather than here */
/* if done in shade.c, we could do volumetric objects */
/* after solids are already known and handle */
/* object-volume intersections better. */
transcol = shade_transmission(ry, &shadevars, 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;
}
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