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
|
// This work is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License.
// To view a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/ or send a
// letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA.
// Persistence Of Vision raytracer sample file.
//
// ------------------------------
// Features pseudo-Gaussian distribution and use of trace function
// Collision algorithm by Greg M. Johnson 2001
// ------------------------------
// ------------------------------
// visibility test
// code by Gilles Tran, derived from work by John Van Sickle and Christoph Hormann
// ------------------------------
#declare CamD=vnormalize(CamEye-CamLoc); // direction of camera view
#declare CamR=vnormalize(vcross(CamSky,CamD)); // to the right
#declare CamU=vnormalize(vcross(CamD,CamR)); // camera up
#declare Screen= // pseudo screen to test the visibility of an object
mesh{
triangle{0,x,x+y}
triangle{0,y,x+y}
translate -0.5*(x+y)
scale <AspectRatio,1,1>
translate CamZoom*z
matrix < CamR.x, CamR.y, CamR.z,
CamU.x, CamU.y, CamU.z,
CamD.x, CamD.y, CamD.z,
CamLoc.x,CamLoc.y,CamLoc.z >
}
#macro IsObjectVisible(PosObject)
// this macro tests the position of the object against the pseudo screen
// note: it also returns false when the position is higher than y=10
#local Norm1 = <0, 0, 0>;
#local PosTemp= trace (Screen,PosObject,-PosObject+CamLoc,Norm1);
#if (vlength(Norm1)!=0 & PosObject.y <10)
true;
#else
false;
#end
#end
//object{Screen pigment{rgbf<1,0,0,0.9>}}
// ------------------------------
// Greg Johnson's algorithm
// ------------------------------
// cube random position
// ------------------------------
#macro randsq(RRR)
#local A=360*rand(RRR);
#local D=5*(1/rand(RRR)-0.75);
#if (D*sin(radians(A))>9) // clipped to let the POVRAY letters visible
#local A = A+180;
#end
vaxis_rotate(x*D,y,A)
#end
// ------------------------------
// cube placement routine
// ------------------------------
#declare R2R=seed(1923);
#declare S = seed(14400);
#declare Norm=<0,0,0>;
#declare ntests=10;
#declare stored=array[ntests+2][ntests+2]
#declare Posy=array[num]
#declare Posy[0]=randsq(S);
// pseudo box used for collision testing
#declare Pseudo=mesh{triangle{0,x,x+z}triangle{0,z,x+z} translate -x*0.5-z*0.5+y*0.5}
// ------------------------------
// generates the first set of cubes that read POVRAY
// ------------------------------
#declare R=array[6]
#declare T=array[6]
#declare i=0;
#while (i<6) // rotations and positions are put in arrays so that they're the same in the file and in the "ally" object
#declare R[i]=<0,-10+25*rand(R2R),0>;
#declare T[i]=<-0.5+rand(R2R),0,rand(R2R)-0.5>;
#declare i=i+1;
#end
#declare ally=union{
object{Pseudo rotate R[0] translate <-4,0.5,-10>+0.35*T[0]}
object{Pseudo rotate R[1] translate <-2.50,0.5,-10>+0.35*T[1]}
object{Pseudo rotate x*90 rotate R[2] translate <-1,0.5,-10>+0.35*T[2]}
object{Pseudo rotate x*90 rotate R[3] translate < 0.50,0.5,-10>+0.35*T[3]}
object{Pseudo rotate R[4] translate < 2,0.5,-10>+0.35*T[4]}
object{Pseudo rotate R[5] translate < 4,0.5,-10>+0.35*T[5]}
}
#fopen StackFile "stacks.inc" write
#write (StackFile, "union{\n")
#write (StackFile, "object{unitbox() rotate -90*y rotate ",R[0]," translate <-4,0.5,-10>+0.35*",T[0],"}\n")
#write (StackFile, "object{unitbox() rotate ",R[1]," translate <-2.5,0.5,-10>+0.35*",T[1],"}\n")
#write (StackFile, "object{unitbox() rotate 90*y rotate ",R[2]," translate <-1,0.5,-10>+0.35*",T[2],"}\n")
#write (StackFile, "object{unitbox() rotate 180*y rotate ",R[3]," translate <0.5,0.5,-10>+0.35*",T[3],"}\n")
#write (StackFile, "object{unitbox() rotate -90*x rotate ",R[4]," translate <2,0.5,-10>+0.35*",T[4],"}\n")
#write (StackFile, "object{unitbox() rotate 90*x rotate ",R[5]," translate <4,0.5,-10>+0.35*",T[5],"}\n")
// ------------------------------
// main placement loop
// runs only if WriteFile is true
// ------------------------------
#declare n=1;
#while(n<num)
#debug concat(str(n,4,0),":")
#declare rotey=rand(R2R)*360;
#declare okayness=no;
#declare counter=0 ;
#while(counter<50)
#declare testcenter=randsq(S);
#declare Visible=IsObjectVisible(testcenter)
#if (Visible)
#declare maxy=-1000;
#declare nx=0;
#while(nx<ntests)
#declare nz=0;
#while (nz<ntests)
#declare testpoint=<-0.5,-0.5,-0.5>+<nx/ntests,0,nz/ntests>;
#declare tracey=trace(ally,testcenter+y*1000+vaxis_rotate(testpoint,y,rotey),-y,Norm);
#if (maxy<tracey.y)
#declare maxy=tracey.y;
#end
#declare stored[nx][nz]=tracey.y;
#declare nz=nz+1;
#end
#declare nx=nx+1;
#end
#declare nnnn=int(ntests/2);
#if(abs(stored[nnnn][nnnn]-maxy)<0.01)
#declare okayness=yes;
#debug "[y]"
#else
#debug "[n]"
#declare netbalancevect=<0,0,0>;
#declare nx=0;
#while(nx<ntests)
#declare nz=0;
#while (nz<ntests)
#if (abs(stored[nx][nz]-maxy)<0.01)
#declare netbalancevect=netbalancevect+<nx-nnnn,0,nz-nnnn>;
#end
#declare nz=nz+1;
#end
#declare nx=nx+1;
#end
#if (vlength(netbalancevect)<0.5)
#declare okayness=yes;
#end
#end
#if(okayness=yes)
#declare counter=counter+100;
#end
#declare counter=counter+1;
#else
#declare counter=counter+100;
#debug "[out]"
#end
#end
#if(Visible)
#declare Posy[n]=testcenter+<0,maxy+0.5,0>;
#declare Visible=IsObjectVisible(Posy[n])
#if (Visible)
#declare R[0]=<int(rand(R2R)*4)*90,0,int(rand(R2R)*4)*90>;
#write (StackFile, "object{unitbox() rotate ",R[0]," rotate y*",rotey," translate ", Posy[n],"}\n")
#declare ally=union{
object{ally}
object{Pseudo rotate y*rotey translate Posy[n]}
}
#else
#debug "[out]"
#end
#end
#debug "\n"
#declare n=n+1;
#end
#write (StackFile, "}")
#fclose StackFile
|
