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#include "config.h"
#include "point.h"
#include "vector.h"
#include "eval.h"
#include "object.h"
#include "intersect.h"
#include "light.h"
struct light * dirlight(struct point * dir, struct point * c)
{
struct light * l = arena_alloc(sizeof(struct light));
l->kind = Directional;
l->u.directional.dir = *dir;
l->u.directional.col = *c;
return l;
}
struct light * pointlight(struct point * orig, struct point * c)
{
struct light * l = arena_alloc(sizeof(struct light));
l->kind = Pointlight;
l->u.point.orig = *orig;
l->u.point.col = *c;
return l;
}
struct light * spotlight(struct point * pos, struct point * at,
struct point * c, flt cutoff, flt exp)
{
struct light * l = arena_alloc(sizeof(struct light));
struct vector uv;
l->kind = Spot;
l->u.spot.orig = *pos;
l->u.spot.at = *at;
l->u.spot.col = *c;
l->u.spot.cutoff = cutoff;
l->u.spot.exponent = exp;
between(at, pos, &uv);
vnormalize(&uv, &(l->u.spot.unit));
return l;
}
static void color_from_light(struct object * scene,
struct point * pt,
struct vector * v,
struct vector * n,
flt kd, flt ks, flt phong,
struct light * light,
/*out*/ struct point * il)
{
struct vector dir;
struct object * obj;
struct vector L, H, vnorm;
struct point i;
flt t, att, dp, m;
/* Compute direction towards light source */
switch (light->kind) {
case Directional:
dir.dx = - light->u.directional.dir.x;
dir.dy = - light->u.directional.dir.y;
dir.dz = - light->u.directional.dir.z;
break;
case Pointlight:
between(pt, &light->u.point.orig, &dir);
break;
case Spot:
between(pt, &light->u.spot.orig, &dir);
break;
}
/* Check that light source is not behind us */
if (dotproduct(&dir, n) <= 0.0) return; /*no contribution*/
/* Check that no object blocks the light */
obj = intersect_ray(pt, &dir, scene, 0 /*??*/, &t);
if (obj != NULL && (light->kind == Directional || t <= 1.0)) return;
/* Compute the L and H vectors */
vnormalize(&dir, &L);
vnormalize(v, &vnorm);
vsub(&L, &vnorm, &H);
vnormalize(&H, &H);
/* Intensity of light source at object */
switch (light->kind) {
case Directional:
i = light->u.directional.col;
break;
case Pointlight:
att = 100.0 / (99.0 + dist2(pt, &light->u.point.orig));
i.x = light->u.point.col.x * att;
i.y = light->u.point.col.y * att;
i.z = light->u.point.col.z * att;
break;
case Spot:
dp = dotproduct(&L, &light->u.spot.unit);
if (acos(dp) >= light->u.spot.cutoff) return;
att =
pow(dp, light->u.spot.exponent)
* (100.0 / (99.0 + dist2(pt, &light->u.spot.orig)));
i.x = light->u.spot.col.x * att;
i.y = light->u.spot.col.y * att;
i.z = light->u.spot.col.z * att;
break;
}
/* Add final contribution */
m = kd * dotproduct(n, &L) + ks * pow(dotproduct(n, &H), phong);
il->x += m * i.x;
il->y += m * i.y;
il->z += m * i.z;
}
void color_from_lights(struct object * scene,
struct point * p,
struct vector * v,
struct vector * n,
flt kd, flt ks, flt phong,
struct light ** lights,
/*out*/ struct point * il)
{
int i;
il->x = il->y = il->z = 0.0;
for (i = 0; lights[i] != NULL; i++)
color_from_light(scene, p, v, n, kd, ks, phong, lights[i], il);
}
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