[Add] A* algorithm to get paths between systems.
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Allanis
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ccb954324c
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472579aa2a
222
src/space.c
222
src/space.c
@ -1,6 +1,9 @@
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#include <malloc.h>
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#include <math.h>
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#include <float.h>
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#include "xml.h"
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#include "lephisto.h"
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#include "log.h"
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#include "physics.h"
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#include "rng.h"
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@ -47,9 +50,9 @@ static int spacename_nstack = 0;
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// Star system stack and co.
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StarSystem* systems_stack = NULL; // Star system stack.
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int systems_nstack = 0; // Number of star systems.
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static int nplanets = 0; // Total number of loaded planets - A little silly.
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StarSystem* cur_system = NULL; // Current star system.
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int systems_nstack = 0; // Number of star systems.
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static int nplanets = 0; // Total number of loaded planets - A little silly.
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StarSystem* cur_system = NULL; // Current star system.
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// Fleet spawn rate.
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unsigned int spawn_timer = 0; // Controls spawn rate.
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@ -62,10 +65,11 @@ typedef struct Star_ {
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} Star;
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static Star* stars = NULL; // Star array.
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static int nstars = 0; // Total stars.
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static int mstars = 0; // Memory stars are taking.
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static int nstars = 0; // Total stars.
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static int mstars = 0; // Memory stars are taking.
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// Intern
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// Intern.
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static StarSystem* system_get(const char* sysname);
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static Planet* planet_get(const char* name);
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static void space_addFleet(Fleet* fleet);
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static StarSystem* system_parse(const xmlNodePtr parent);
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@ -139,6 +143,200 @@ void planets_minimap(const double res,
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}
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#undef PIXEL
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// A* Algorithm fo shortest path finding.
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// The node struct.
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typedef struct SysNode_ {
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struct SysNode_* next;
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struct SysNode_* parent;
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StarSystem* sys;
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double r; // Ranking.
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int g; // Step.
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} SysNode;
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static SysNode* gc;
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// Prototypes.
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static SysNode* A_newNode(StarSystem* sys, SysNode* parent);
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static double A_h(StarSystem* n, StarSystem* g);
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static double A_g(SysNode* n);
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static SysNode* A_add(SysNode* first, SysNode* cur);
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static SysNode* A_rm(SysNode* first, StarSystem* cur);
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static int A_in(SysNode* first, StarSystem* cur);
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static SysNode* A_lowest(SysNode* first);
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static void A_freeList(SysNode* first);
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// Creates a new node link to star system.
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static SysNode* A_newNode(StarSystem* sys, SysNode* parent) {
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SysNode* n;
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n = malloc(sizeof(SysNode));
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n->next = NULL;
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n->parent = parent;
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n->sys = sys;
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n->r = DBL_MAX;
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n->g = 0.;
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A_add(gc, n);
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return n;
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}
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static double A_h(StarSystem* n, StarSystem* g) {
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// Euclidean distance.
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return sqrt(pow2(n->pos.x - g->pos.x) + pow2(n->pos.y - g->pos.y))/100.;
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}
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// Get the g from a node.
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static double A_g(SysNode* n) {
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return n->g;
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}
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// Add a node to the linkes list.
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static SysNode* A_add(SysNode* first, SysNode* cur) {
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SysNode* n;
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if(first == NULL)
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return cur;
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n = first;
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while(n->next != NULL)
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n = n->next;
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n->next = cur;
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return first;
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}
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// Remove a node from a linked list.
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static SysNode* A_rm(SysNode* first, StarSystem* cur) {
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SysNode* n, *p;
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if(first->sys == cur) {
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first->next = NULL;
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n = first->next;
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return n;
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}
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p = first;
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n = p->next;
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do {
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if(n->sys == cur) {
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n->next = NULL;
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p->next = n->next;
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break;
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}
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} while((n=n->next) != NULL);
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return first;
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}
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// Check if node is in linked list.
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static int A_in(SysNode* first, StarSystem* cur) {
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SysNode* n;
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if(first == NULL)
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return 0;
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n = first;
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do {
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if(n->sys == cur)
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return 1;
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} while((n=n->next) != NULL);
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return 0;
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}
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// Return the lowest ranking node from a linked list of nodes.
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static SysNode* A_lowest(SysNode* first) {
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SysNode* lowest, *n;
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if(first == NULL)
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return NULL;
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n = first;
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lowest = n;
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do {
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if(n->r < lowest->r)
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lowest = n;
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} while((n=n->next) != NULL);
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return lowest;
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}
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// Free a linked list.
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static void A_freeList(SysNode* first) {
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SysNode* p, *n;
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if(first == NULL)
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return;
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p = NULL;
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n = first;
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do {
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if(p != NULL)
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free(p);
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p = n;
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} while((n=n->next) != NULL);
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free(p);
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}
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StarSystem** system_getJumpPath(int* njumps, char* sysstart, char* sysend) {
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int i, cost;
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StarSystem* ssys, *esys, **res;
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SysNode* cur, *neighbour;
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SysNode* open, *closed;
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gc = NULL;
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// Initial and target systems.
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ssys = system_get(sysstart); // Start.
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ssys = system_get(sysend); // End.
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// Start the linked lists.
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open = closed = NULL;
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cur = A_newNode(ssys, NULL);
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open = A_add(open, cur); // Initial open node is the start system.
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while((cur = A_lowest(open))->sys != esys) {
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// Get best from open and toss to closed.
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open = A_rm(open, cur->sys);
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closed = A_add(closed, cur);
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for(i = 0; i < cur->sys->njumps; i++) {
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neighbour = A_newNode(&systems_stack[cur->sys->jumps[i]], cur);
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cost = A_g(cur) + 1;
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if(A_in(open, neighbour->sys) && (cost < A_g(neighbour)))
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open = A_rm(open, neighbour->sys); // New path is better.
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if(A_in(closed, neighbour->sys) && (cost < A_g(neighbour)))
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closed = A_rm(closed, neighbour->sys); // Shouldn't happen.
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if(!A_in(open, neighbour->sys) && !A_in(closed, neighbour->sys)) {
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neighbour->g = cost;
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open = A_add(open, neighbour);
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neighbour->r = (double)A_g(neighbour) + A_h(neighbour->sys, esys);
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}
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}
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}
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// Build the path backwards.
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(*njumps) = A_g(cur);
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res = malloc(sizeof(StarSystem*) * (*njumps));
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for(i = 0; i < (*njumps); i++) {
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res[(*njumps)-i-1] = cur->sys;
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cur = cur->parent;
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}
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// Free the linked list.
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//A_freeList(open);
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//A_freeList(closed);
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A_freeList(gc);
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return res;
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}
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static PlanetClass planetclass_get(const char a) {
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switch(a) {
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// Planets use letters.
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@ -256,6 +454,18 @@ char* space_getRndPlanet(void) {
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return res;
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}
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// Get the system from it's name.
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static StarSystem* system_get(const char* sysname) {
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int i;
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for(i = 0; i < systems_nstack; i++)
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if(strcmp(sysname, systems_stack[i].name)==0)
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return &systems_stack[i];
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DEBUG("System '%s' not found in stack", sysname);
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return NULL;
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}
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// Get the name of a system from a planetname.
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char* planet_getSystem(char* planetname) {
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int i;
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21
src/space.h
21
src/space.h
@ -69,26 +69,26 @@ typedef struct Planet_ {
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// Star systems.
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typedef struct SystemFleet_ {
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Fleet* fleet; // Fleet to appear.
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int chance; // Chance of fleet appearing in the system.
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Fleet* fleet; // Fleet to appear.
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int chance; // Chance of fleet appearing in the system.
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} SystemFleet;
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typedef struct StarSystem_ {
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char* name; // Star system identifier.
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Vec2 pos; // Position.
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char* name; // Star system identifier.
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Vec2 pos; // Position.
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int stars, asteroids; // Un numero!
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double interference; // Un uh.. Percentage.
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int faction; // Overall faction.
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int faction; // Overall faction.
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Planet* planets; // Planets.
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int nplanets; // Total number of planets.
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Planet* planets; // Planets.
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int nplanets; // Total number of planets.
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SystemFleet* fleets; // Fleets that can appear in the current system.
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int nfleets; // Total number of fleets.
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int nfleets; // Total number of fleets.
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int* jumps; // Adjacent star system index number.
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int njumps; // Number of adjacent jumps.
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int* jumps; // Adjacent star system index number.
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int njumps; // Number of adjacent jumps.
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} StarSystem;
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extern StarSystem* cur_system; // Current star system.
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@ -109,6 +109,7 @@ void planets_render(void);
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void space_update(const double dt);
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// Misc.
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StarSystem** system_getJumpPath(int* njumps, char* sysstart, char* sysend);
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int space_canHyperspace(Pilot* p);
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int space_hyperspace(Pilot* p);
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char** space_getFactionPlanet(int* nplanets, int* factions, int nfactions);
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