1 /*
2     Copyright (c) 2005-2020 Intel Corporation
3 
4     Licensed under the Apache License, Version 2.0 (the "License");
5     you may not use this file except in compliance with the License.
6     You may obtain a copy of the License at
7 
8         http://www.apache.org/licenses/LICENSE-2.0
9 
10     Unless required by applicable law or agreed to in writing, software
11     distributed under the License is distributed on an "AS IS" BASIS,
12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13     See the License for the specific language governing permissions and
14     limitations under the License.
15 */
16 
17 /*
18     The original source for this example is
19     Copyright (c) 1994-2008 John E. Stone
20     All rights reserved.
21 
22     Redistribution and use in source and binary forms, with or without
23     modification, are permitted provided that the following conditions
24     are met:
25     1. Redistributions of source code must retain the above copyright
26        notice, this list of conditions and the following disclaimer.
27     2. Redistributions in binary form must reproduce the above copyright
28        notice, this list of conditions and the following disclaimer in the
29        documentation and/or other materials provided with the distribution.
30     3. The name of the author may not be used to endorse or promote products
31        derived from this software without specific prior written permission.
32 
33     THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
34     OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
35     WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
36     ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
37     DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
38     DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
39     OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
40     HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
41     LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
42     OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43     SUCH DAMAGE.
44 */
45 
46 /*
47  * intersect.cpp - This file contains code for CSG and intersection routines.
48  */
49 
50 #include "machine.hpp"
51 #include "types.hpp"
52 #include "intersect.hpp"
53 #include "light.hpp"
54 #include "util.hpp"
55 #include "global.hpp"
56 
57 unsigned int new_objectid(void) {
58     return numobjects++; /* global used to generate unique object ID's */
59 }
60 
61 unsigned int max_objectid(void) {
62     return numobjects;
63 }
64 
65 void add_object(object *obj) {
66     object *objtemp;
67 
68     if (obj == nullptr)
69         return;
70 
71     obj->id = new_objectid();
72 
73     objtemp = rootobj;
74     rootobj = obj;
75     obj->nextobj = objtemp;
76 }
77 
78 void free_objects(object *start) {
79     object *cur;
80     object *cur2;
81 
82     cur = start;
83     while (cur->nextobj != nullptr) {
84         cur2 = (object *)cur->nextobj;
85         cur->methods->free(cur);
86         cur = cur2;
87     }
88     free(cur);
89 }
90 
91 void reset_object(void) {
92     if (rootobj != nullptr)
93         free_objects(rootobj);
94 
95     rootobj = nullptr;
96     numobjects = 0; /* set number of objects back to 0 */
97 }
98 
99 void intersect_objects(ray *intray) {
100     object *cur;
101     object temp;
102 
103     temp.nextobj = rootobj; /* setup the initial object pointers.. */
104     cur = &temp; /* ready, set                          */
105 
106     while ((cur = (object *)cur->nextobj) != nullptr)
107         cur->methods->intersect(cur, intray);
108 }
109 
110 void reset_intersection(intersectstruct *intstruct) {
111     intstruct->num = 0;
112     intstruct->list[0].t = FHUGE;
113     intstruct->list[0].obj = nullptr;
114     intstruct->list[1].t = FHUGE;
115     intstruct->list[1].obj = nullptr;
116 }
117 
118 void add_intersection(flt t, object *obj, ray *ry) {
119     intersectstruct *intstruct = ry->intstruct;
120 
121     if (t > EPSILON) {
122         /* if we hit something before maxdist update maxdist */
123         if (t < ry->maxdist) {
124             ry->maxdist = t;
125 
126             /* if we hit *anything* before maxdist, and we're firing a */
127             /* shadow ray, then we are finished ray tracing the shadow */
128             if (ry->flags & RT_RAY_SHADOW)
129                 ry->flags |= RT_RAY_FINISHED;
130         }
131 
132         intstruct->num++;
133         intstruct->list[intstruct->num].obj = obj;
134         intstruct->list[intstruct->num].t = t;
135     }
136 }
137 
138 int closest_intersection(flt *t, object **obj, intersectstruct *intstruct) {
139     int i;
140     *t = FHUGE;
141 
142     for (i = 1; i <= intstruct->num; i++) {
143         if (intstruct->list[i].t < *t) {
144             *t = intstruct->list[i].t;
145             *obj = intstruct->list[i].obj;
146         }
147     }
148 
149     return intstruct->num;
150 }
151 
152 int shadow_intersection(intersectstruct *intstruct, flt maxdist) {
153     int i;
154 
155     if (intstruct->num > 0) {
156         for (i = 1; i <= intstruct->num; i++) {
157             if ((intstruct->list[i].t < maxdist) &&
158                 (intstruct->list[i].obj->tex->shadowcast == 1)) {
159                 return 1;
160             }
161         }
162     }
163 
164     return 0;
165 }
166