1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206

207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262

#define _CRT_SECURE_NO_WARNINGS

// sphere flake bvh raytracer (c) 2005, thierry berger-perrin <tbptbp@gmail.com>
// this code is released under the GNU Public License.
#include <cmath>       // see http://ompf.org/ray/sphereflake/
#include <iostream>    // compile with ie g++ -O2 -ffast-math sphereflake.cc
#include <limits>
#include <stdlib.h>
#include "Profiler.h"
#define GIMME_SHADOWS  // usage: ./sphereflake [lvl=6] >pix.ppm

//#define SINGLE_THREADED

#if !defined(SINGLE_THREADED)
	#if defined(_MSC_VER)
		#include <windows.h>
		#undef min
		#undef max
		typedef HANDLE thread_handle;
		#define THREAD_FUNC() DWORD WINAPI
		typedef DWORD (WINAPI *thread_function)( void * );
		thread_handle thread_create( thread_function thread, void *parm ) { DWORD id; return CreateThread( NULL, 0, thread, parm, 0, &id ); }
		void thread_wait( thread_handle h ) { PROFILE_PAUSE_SCOPED() WaitForSingleObject( h, INFINITE ); }
		void thread_close( thread_handle h ) { CloseHandle( h ); }
	#else
		#include <pthread.h>
		typedef pthread_t thread_handle;
		#define THREAD_FUNC() static void *
		typedef void *(*thread_function)( void * );
		thread_handle thread_create( thread_function thread, void *parm ) { thread_handle h; pthread_create( &h, NULL, thread, parm ); return h; }
		void thread_wait( thread_handle h ) { PROFILE_PAUSE_SCOPED() pthread_join( h, NULL ); }
		void thread_close( thread_handle h ) {}
	#endif
#endif

enum { childs = 9, ss= 2, ss_sqr = ss*ss }; /* not really tweakable anymore */
static const double infinity = std::numeric_limits<double>::infinity( ), epsilon = 1e-12;
#undef M_PI
#define M_PI 3.14159265358979323846

struct v_t{ double x,y,z;v_t(){}
	v_t(const double a,const double b,const double c):x(a),y(b),z(c){}
	v_t operator+(const v_t&v)const{return v_t(x+v.x,y+v.y,z+v.z);}
	v_t operator-(const v_t&v)const{return v_t(x-v.x,y-v.y,z-v.z);}
	v_t operator-()const{return v_t(-x,-y,-z);}
	v_t operator*(const double d)const{return v_t(x*d,y*d,z*d);}
	v_t cross(const v_t&v)const{return v_t(y*v.z-z*v.y,z*v.x-x*v.z,x*v.y-y*v.x);}
	v_t norm()const{return*this*(1./sqrt(magsqr()));}
	double dot(const v_t&v)const{return x*v.x+y*v.y+z*v.z;}
	double magsqr()const{return dot(*this);}
};

//static const v_t light(v_t(0.5,-.95,1.775).norm()); /*pick one*/
static const v_t light(v_t(-0.5,-.65,.9).norm()); /*fiat lux*/

struct ray_t{
	v_t o,d;
	ray_t(const v_t&v):o(v){}
	 ray_t(const v_t&v,const v_t&w):o(v),d(w){}
};
struct hit_t {
	v_t n;
	double t;
	hit_t():n(v_t(0,0,0)),t(infinity){}
};

struct sphere_t{ 
	v_t o;
	double r;
	sphere_t(){}
	sphere_t(const v_t&v,double d):o(v),r(d){}
	v_t get_normal(const v_t&v)const{return(v-o)*(1./r);}
	double intersect(const ray_t&ray)const{
		//PROFILE_SCOPED()
		const v_t v(o-ray.o); const double b=ray.d.dot(v),disc=b*b-v.magsqr()+r*r;
		if(disc < 0.)
			return infinity; /*branch away from the square root*/
		const double d=sqrt(disc), t2=b+d, t1=b-d; /*cond. move*/
		if(t2 < 0.)
			return infinity;
		else
			return(t1 > 0.? t1 : t2);
	}
};

struct node_t; 
static node_t *pool=0, *end=0;

struct node_t { /*a bvh in array form+skip for navigation.*/
	sphere_t bound,leaf;
	long diff;/*far from optimal*/
	node_t(){} node_t(const sphere_t&b,const sphere_t&l,const long jump) :bound(b),leaf(l),diff(jump){}
	template<bool shadow> static void intersect(const ray_t &ray,hit_t &hit){
		PROFILE_SCOPED()

		const node_t*p=pool;
		while(p < end) {
			if(p->bound.intersect(ray)>=hit.t) /*missed bound*/
				p+=p->diff; /*skip subtree*/
			else{
				const double t=p->leaf.intersect(ray);
				if(t < hit.t) { /*if hit, update, then break for shadows*/
					 hit.t=t;
					if(shadow) break;
					hit.n=p->leaf.get_normal(ray.o+ray.d*t);
				}
				++p; /*next!*/
			}
		}
	}
};

static double ray_trace(const node_t*const scene,const ray_t&ray) {
	PROFILE_SCOPED()

	hit_t hit;
	scene->intersect<false>(ray,hit);// trace primary
	const double diffuse = hit.t==infinity ? 0. : -hit.n.dot(light);
	#ifdef GIMME_SHADOWS
		if (diffuse <= 0.)
			return 0.;
		const ray_t sray(ray.o+(ray.d*hit.t)+(hit.n*epsilon),-light);
		hit_t shit;
		scene->intersect<true>(sray,shit);// trace shadow
		return shit.t==infinity ? diffuse : 0.;
	#else
		return diffuse > 0. ? diffuse : 0.;
	#endif
}

static const double grid[ss_sqr][2]={ /*our rotated grid*/
	{-3/3.,-1/3.},{+1/3.,-3/3.},
	{-1/3.,+3/3.},{+3/3.,+1/3.}
};
static void trace_rgss(const int width,const int height,const int start,const int span, char *out) {
	const double w=width,h=height,rcp=1/double(ss),scale=256./double(ss_sqr);
	ray_t ray(v_t(0,0,-4.5)); /* eye, looking into Z */
	v_t rgss[ss_sqr];
	for(int i=0;i<ss_sqr;++i) /*precomp.*/
		rgss[i]=v_t(grid[i][0]*rcp-w/2.,grid[i][1]*rcp-h/2.,0);
	
	v_t scan(0,start,std::max(w,h)); /*scan line*/
	out += (height - start - 1) * width;
	for(int i=span;i;--i) {
		for(int j=width;j;--j) {
			double g=0;
			for(int idx=0;idx < ss_sqr;++idx){ /*AA*/
				ray.d=(scan+rgss[idx]).norm();
				g+=ray_trace(pool,ray); /*trace*/
			}
			*out++ = int(scale*g);
			scan.x+=1; /*next pixel*/
		}
		scan.x=0;scan.y+=1; /*next line*/
		out -= (width * 2);
	}
	//std::cout << std::endl; 
}
	
struct basis_t{ /* bogus and compact, exactly what we need */
	v_t up,b1,b2;
	basis_t(const v_t&v){ 
		PROFILE_SCOPED()

		const v_t n(v.norm());
		if ((n.x*n.x !=1.)&(n.y*n.y !=1.)&(n.z*n.z !=1.)) {/*cough*/
			b1=n;
			if(n.y*n.y>n.x*n.x) {
				if(n.y*n.y>n.z*n.z)
					b1.y=-b1.y;
				else b1.z=-b1.z;
			}
			else if(n.z*n.z > n.x*n.x)
				b1.z=-b1.z;
			else b1.x=-b1.x;
		}
		else
			b1=v_t(n.z,n.x,n.y);/*leaves some cases out,dodge them*/
		
		up=n;
		b2=up.cross(b1);
		b1=up.cross(b2);
	}
};

static node_t *create(node_t*n,const int lvl,int dist,v_t c,v_t d,double r) {
	PROFILE_SCOPED()

	n = 1 + new (n) node_t(sphere_t(c,2.*r),sphere_t(c,r), lvl > 1 ? dist : 1);
	if (lvl <= 1)
		return n; /*if not at the bottom, recurse a bit more*/
	
	dist=std::max((dist-childs)/childs,1); const basis_t b(d); 
	const double nr=r*1/3.,daL=2.*M_PI/6.,daU=2.*M_PI/3.; double a=0;
	for(int i=0;i<6;++i){ /*lower ring*/
		const v_t ndir((d*-.2+b.b1*sin(a)+b.b2*cos(a)).norm()); /*transcendentals?!*/
		n=create(n,lvl-1,dist,c+ndir*(r+nr),ndir,nr);
		a+=daL;
	}
	a-=daL/3.;/*tweak*/
	for(int i=0;i<3;++i){ /*upper ring*/
		const v_t ndir((d*+.6+b.b1*sin(a)+b.b2*cos(a)).norm());
		n=create(n,lvl-1,dist,c+ndir*(r+nr),ndir,nr); a+=daU;
	}
	return n;
}

#if !defined(SINGLE_THREADED)
struct block { int w, h, start, span; thread_handle handle; char *out; };

THREAD_FUNC() trace_launcher( void *arg ) {
	PROFILE_THREAD_SCOPED()
	block &b = *(block *)arg;
	trace_rgss(b.w,b.h,b.start,b.span,b.out); /* served */
	return NULL;
}
#endif

int main(int argc,const char*argv[]){
	Profiler::detect( argc, argv );

	enum{ w = 1024, h = w }; /* resolution */
	const int lvl=(argc>=2?std::max(atoi(argv[1]),2):6);
	const int cpus=(argc>=3?std::max(atoi(argv[2]),1):2), maxcpus = 32;
	int count=childs, dec=lvl;
	while(--dec > 1) count=(count*childs)+childs;
	++count;
	std::cerr << count << " spheres,claiming " << (count*sizeof(node_t))/(1024.*1024) << " MB." << std::endl;
	pool=new node_t[count];  /* raw */
	end=pool+count;
	create(pool,lvl,count,v_t(0,0,0),v_t(+.25,+1,-.5).norm(),1.); /* cooked */
	char *out = new char[w * h];
#if !defined(SINGLE_THREADED)
	int blocksize = h / maxcpus, reps = h / blocksize, rep = 0, nthreads = 0, waitrep = 0;
	block *blocks = new block[reps];
	while ( true ) {
		while ( nthreads < cpus && rep < reps ) {
			block &b = blocks[rep];
			b.w = w; b.h = h; b.span = blocksize; b.start = rep++ * blocksize; b.out = out;
			PROFILE_PAUSE_SCOPED() // thread creation is slow, so don't time it
			b.handle = thread_create( trace_launcher, &b );
			nthreads++;
		}
		thread_wait( blocks[waitrep].handle );
		thread_close( blocks[waitrep].handle );
		nthreads--;
		if ( ++waitrep >= reps )
			break;
	}
	delete[] blocks;
#else
	trace_rgss(w,h,0,h,out);
#endif

	Profiler::dumphtml( );
	Profiler::dump( );
	FILE *f = fopen( "sphereflake.raw", "wb+" );
	fwrite( out, w, h, f );
	fclose( f );
	delete[] out;
	return 0;
}