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#include <u.h>
#include <libc.h>
#include <draw.h>
#include "../geometry.h"
#include "../graphics.h"
static int
max(int a, int b)
{
return a > b ? a : b;
}
static void
verifycfg(Camera *c)
{
assert(c->viewport != nil);
if(c->ptype == Ppersp)
assert(c->fov >= 1 && c->fov < 360);
assert(c->clip.n > 0 && c->clip.n < c->clip.f);
}
void
perspective(Matrix3 m, double fov, double a, double n, double f)
{
double cotan;
cotan = 1/tan(fov/2*DEG);
identity3(m);
m[0][0] = cotan/a;
m[1][1] = cotan;
m[2][2] = -(f+n)/(f-n);
m[2][3] = -2*f*n/(f-n);
m[3][2] = -1;
}
void
orthographic(Matrix3 m, double l, double r, double b, double t, double n, double f)
{
identity3(m);
m[0][0] = 2/(r - l);
m[1][1] = 2/(t - b);
m[2][2] = -2/(f - n);
m[0][3] = -(r + l)/(r - l);
m[1][3] = -(t + b)/(t - b);
m[2][3] = -(f + n)/(f - n);
}
void
configcamera(Camera *c, Image *v, double fov, double n, double f, Projection p)
{
c->viewport = v;
c->fov = fov;
c->clip.n = n;
c->clip.f = f;
c->ptype = p;
reloadcamera(c);
}
void
placecamera(Camera *c, Point3 p, Point3 focus, Point3 up)
{
c->p = p;
if(focus.w == 0)
c->bz = focus;
else
c->bz = normvec3(subpt3(c->p, focus));
c->bx = normvec3(crossvec3(up, c->bz));
c->by = crossvec3(c->bz, c->bx);
}
void
aimcamera(Camera *c, Point3 focus)
{
placecamera(c, c->p, focus, c->by);
}
void
reloadcamera(Camera *c)
{
double a;
double l, r, b, t;
verifycfg(c);
switch(c->ptype){
case Portho:
/*
r = Dx(c->viewport->r)/2;
t = Dy(c->viewport->r)/2;
l = -r;
b = -t;
*/
l = t = 0;
r = Dx(c->viewport->r);
b = Dy(c->viewport->r);
orthographic(c->proj, l, r, b, t, c->clip.n, c->clip.f);
break;
case Ppersp:
a = (double)Dx(c->viewport->r)/Dy(c->viewport->r);
perspective(c->proj, c->fov, a, c->clip.n, c->clip.f);
break;
default: sysfatal("unknown projection type");
}
}
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