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#include <u.h>
#include <libc.h>
#include <thread.h>
#include <draw.h>
#include <memdraw.h>
#include <geometry.h>
#include "graphics.h"
#include "internal.h"
double
sign(double n)
{
return n == 0? 0: n < 0? -1: 1;
}
double
step(double edge, double n)
{
if(n < edge)
return 0;
return 1;
}
double
smoothstep(double edge0, double edge1, double n)
{
double t;
t = fclamp((n-edge0)/(edge1-edge0), 0, 1);
return t*t * (3 - 2*t);
}
/* TODO apply attenuation for punctual lights */
Color
getlightcolor(LightSource *l, Point3 dir)
{
double cθs, cθu, cθp, t;
/* see “Spotlights”, Real-Time Rendering 4th ed. § 5.2.2 */
if(l->type == LightSpot){
cθs = dotvec3(mulpt3(dir, -1), l->dir);
cθu = cos(l->θu);
cθp = cos(l->θp);
// return mulpt3(l->c, smoothstep(cθu, cθp, cθs));
t = fclamp((cθs - cθu)/(cθp - cθu), 0, 1);
return mulpt3(l->c, t*t);
}
return l->c;
}
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