ref: f28701a4f6b817d1e5b325eb81ed4892ebecacbf
dir: /3d06.c/
/* global map + transformed map + perspective,
* floating point coordinates */
#include <u.h>
#include <libc.h>
#include <thread.h>
#include <draw.h>
#include "dat.h"
#include "fns.h"
enum{
Hz = 30,
};
char *progname = "3d05";
int tdiv = Te3 / Hz;
enum{
Cbg,
Cplayer,
Carrow,
Cwall,
Cside,
Cend,
};
static Image *col[Cend];
typedef struct Player Player;
struct Player{
Foint;
double θ;
};
static Player player;
static Fectangle wall;
static double
crossprod(Foint a, Foint b)
{
return a.x * b.y - a.y * b.x; /* = z */
}
static Foint
intersect(Foint p0, Foint p1, Foint p2, Foint p3)
{
double x, y, det;
x = crossprod(p0, p1);
y = crossprod(p2, p3);
det = crossprod(Ft(p0.x - p1.x, p0.y - p1.y), Ft(p2.x - p3.x, p2.y - p2.y));
if(det == 0.0)
det = 1e-9;
x = crossprod(Ft(x, p0.x - p1.x), Ft(y, p2.x - p3.x)) / det;
y = crossprod(Ft(x, p0.y - p1.y), Ft(y, p2.y - p3.y)) / det;
return (Foint){x, y};
}
static void
forward(void)
{
player.x += cos(player.θ);
player.y += sin(player.θ);
}
static void
backward(void)
{
player.x -= cos(player.θ);
player.y -= sin(player.θ);
}
static void
turnleft(void)
{
player.θ -= 0.1;
}
static void
turnright(void)
{
player.θ += 0.1;
}
static void
transleft(void)
{
player.x += sin(player.θ);
player.y -= cos(player.θ);
}
static void
transright(void)
{
player.x -= sin(player.θ);
player.y += cos(player.θ);
}
Key keys[] = {
{'w', forward},
{'s', backward},
{'a', turnleft},
{'d', turnright},
{'q', transleft},
{'e', transright},
};
int nkeys = nelem(keys);
static void
stepsim(void)
{
Key *k;
for(k=keys; k<keys+nkeys; k++)
if(k->down)
k->fn();
}
static void
render(void)
{
Player pl;
Foint z1, z2;
Fectangle r, wl, rwl;
Rectangle top, bottom;
draw(fb, fb->r, col[Cbg], nil, ZP);
wl = wall;
pl = player;
/* absolute map */
line(fb, PFt(wl.min), PFt(wl.max), 0, 0, 1, col[Cwall], ZP);
ellipse(fb, Pt(pl.x, pl.y), 2, 2, 0, col[Cplayer], ZP);
line(fb, Pt(pl.x, pl.y),
Pt(pl.x + cos(player.θ) * 15, pl.y + sin(player.θ) * 15),
0, 0, 0, col[Carrow], ZP);
/* transform vertices relative to player coordinates */
wl.min.x -= pl.x;
wl.min.y -= pl.y;
wl.max.x -= pl.x;
wl.max.y -= pl.y;
rwl.min.x = wl.min.x * sin(player.θ) - wl.min.y * cos(player.θ);
rwl.min.y = wl.min.x * cos(player.θ) + wl.min.y * sin(player.θ); /* now left depth (since camera looks towards -∞ along y axis */
rwl.max.x = wl.max.x * sin(player.θ) - wl.max.y * cos(player.θ);
rwl.max.y = wl.max.x * cos(player.θ) + wl.max.y * sin(player.θ); /* now right depth */
/* offset view */
pl.x = 200;
pl.y = 50;
r.min.x = pl.x - rwl.min.x;
r.min.y = pl.y - rwl.min.y;
r.max.x = pl.x - rwl.max.x;
r.max.y = pl.y - rwl.max.y;
line(fb, PFt(r.min), PFt(r.max), 0, 0, 1, col[Cwall], ZP);
ellipse(fb, Pt(pl.x, pl.y), 2, 2, 0, col[Cplayer], ZP);
line(fb, Pt(pl.x, pl.y),
Pt(pl.x + cos(-PI/2) * 15, pl.y + sin(-PI/2) * 15),
0, 0, 0, col[Carrow], ZP);
/* perspective-transformed map:
* just take the transformed wall coordinates and divide by depth */
/* first clip line if it crosses the player's viewplane,
* ie. when one of the depth coordinates is negative;
* if both are negative, it is behind the player */
if(rwl.min.y <= 0 && rwl.max.y <= 0)
return;
if(rwl.min.y == 0)
rwl.min.y = 1;
if(rwl.max.y == 0)
rwl.max.y = 1;
z1 = intersect(Ft(rwl.min.x, rwl.min.y), Ft(rwl.max.x, rwl.max.y), Ft(-1e-4, 1e-4), Ft(-20, 5));
z2 = intersect(Ft(rwl.min.x, rwl.min.y), Ft(rwl.max.x, rwl.max.y), Ft(1e-4, 1e-4), Ft(20, 5));
if(rwl.min.y <= 0){
if(z1.y > 0)
rwl.min.x = z1.x, rwl.min.y = z1.y;
else
rwl.min.x = z2.x, rwl.min.y = z2.y;
}
if(rwl.max.y <= 0){
if(z1.y > 0)
rwl.max.x = z1.x, rwl.max.y = z1.y;
else
rwl.max.x = z2.x, rwl.max.y = z2.y;
}
/* length of the wall = 50 (euclidean distance), we divide for smaller viewsize */
top.min.x = 50 - rwl.min.x * 50/2 / rwl.min.y;
top.max.x = 50 - rwl.max.x * 50/2 / rwl.max.y;
top.min.y = 50 + -50 / rwl.min.y;
top.max.y = 50 + -50 / rwl.max.y;
bottom.min.x = top.min.x;
bottom.max.x = top.max.x;
bottom.min.y = 50 + 50 / rwl.min.y;
bottom.max.y = 50 + 50 / rwl.max.y;
/* offset view */
pl.x = 300;
top = rectaddpt(top, Pt(pl.x, pl.y));
bottom = rectaddpt(bottom, Pt(pl.x, pl.y));
line(fb, top.min, top.max, 0, 0, 1, col[Cwall], ZP);
line(fb, bottom.min, bottom.max, 0, 0, 1, col[Cwall], ZP);
line(fb, top.min, bottom.min, 0, 0, 1, col[Cside], ZP);
line(fb, top.max, bottom.max, 0, 0, 1, col[Cside], ZP);
}
static void
initrender(void)
{
col[Cbg] = display->black;
col[Cplayer] = display->white;
col[Carrow] = eallocimage(Rect(0,0,1,1), screen->chan, 1, 0x777777ff);
col[Cwall] = eallocimage(Rect(0,0,1,1), screen->chan, 1, DYellow);
col[Cside] = eallocimage(Rect(0,0,1,1), screen->chan, 1, DRed);
}
static void
initsim(void)
{
wall = (Fectangle){(Foint){70, 20}, (Foint){70, 70}};
player = (Player){(Foint){50, 50}, 0};
}
void
threadmain(int, char**)
{
sysinit(initrender, initsim, render, stepsim);
sim();
}