著名物理引擎Hawk的源代码

				/* object.c, HAWK game engine
				 *
				 * Copyright 1997-1998 by Phil Frisbie, Jr.
				 * for Hawk Software
				 *
				 */
				
				#include "hawk.h"
				#include "internal.h"
				
				int			nfreeobjects;
				OBJECT		*firstobject;
				OBJECT		*firstfreeobject;
				OBJECT		*objects;
				OBJECT		*lastobject;
				
				static BOOL needinit = TRUE;
				
				void objInit(void)
				{
					int	i;
				
					GLevel.nobjects = 0;
					GLevel.objects = TagMalloc(MAX_OBJECTS * sizeof(GLevel.objects[0]), TAG_LEVEL);
					memset(GLevel.objects, 0, MAX_OBJECTS * sizeof(GLevel.objects[0]));
					objects = GLevel.objects;
					for(i=0;i					{
						if(i != (MAX_OBJECTS - 1))
							objects[i].next = &objects[i+1];
						else
							objects[i].next = NULL;
						if(i != 0)
							objects[i].prev = &objects[i-1];
						else
							objects[i].prev = NULL;
					}
					firstfreeobject = &objects[0];
					firstobject = NULL;
					lastobject = NULL;
					needinit = FALSE;
				}
				
				OBJECT *objAdd(void)
				{
					int i;
				
					if(needinit)
						objInit();
					 /* find an unused object */
					if(GLevel.nobjects == 0) /* cannot chain for first object */
					{
						GLevel.objects[0].next = NULL;
						if(!GLevel.objects[0].trace)
							GLevel.objects[0].trace = TagMalloc(sizeof(TRACE), TAG_LEVEL);
						GLevel.objects[0].weapon = NO_MODEL;
						GLevel.nobjects++;
						return &GLevel.objects[0];
					}
					else
					{
						for(i=0;i						{
							if(GLevel.objects[i].type == O_UNUSED) /* found an unused object */
							{
								int j;
								/* find the last object in the chain */
								for(j=0;j								{
									if((!GLevel.objects[j].next)
											&& (GLevel.objects[j].type)) /* found the last used object in the chain */					{
										GLevel.objects[j].next = &GLevel.objects[i];
										GLevel.objects[i].next = NULL;
										if(!GLevel.objects[i].trace)
											GLevel.objects[i].trace = TagMalloc(sizeof(TRACE), TAG_LEVEL);
										GLevel.objects[i].weapon = NO_MODEL;
										GLevel.nobjects++;
										return &GLevel.objects[i];
									}
								}
							}
						}
					}
					/* we must be out of objects */
					return NULL;
				}
				
				void objDelete(OBJECT *o)
				{
					int i;
				
					 /* find the object */
					for(i=0;i					{
						if(o == &GLevel.objects[i]) /* found the object */
						{
							int j;
							/* find the previous object in the chain */
							for(j=0;j							{
								if(o == (OBJECT *)GLevel.objects[j].next) /* found the previous object in the chain */
								{
									GLevel.objects[j].next = o->next;
									o->next = NULL;
									o->type = O_UNUSED;
									GLevel.nobjects--;
								}
							}
						}
					}
				}