added rectangle binary search tree as collision index.
This commit is contained in:
Antonio Carzaniga
parent
a8e616a608
commit
956e652827
262
balls.c
262
balls.c
@ -24,28 +24,26 @@ struct ball {
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cairo_surface_t * surface;
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};
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static int collisions = 1;
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double delta = 0.01; /* seconds */
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static double delta = 0.01; /* seconds */
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unsigned int width = DEFAULT_WIDTH;
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unsigned int height = DEFAULT_HEIGHT;
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static unsigned int width = DEFAULT_WIDTH;
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static unsigned int height = DEFAULT_HEIGHT;
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unsigned int radius_min = 5;
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unsigned int radius_max = 10;
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static unsigned int radius_min = 5;
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static unsigned int radius_max = 10;
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static unsigned int v_max = 100;
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static unsigned int v_min = 0;
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unsigned int v_max = 100;
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unsigned int v_min = 0;
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struct ball * balls = 0;
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unsigned int n_balls = 50;
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static double g_y = 20;
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static double g_x = 0;
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double g_y = 20;
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double g_x = 0;
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static double clear_alpha = 1.0;
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double clear_alpha = 1.0;
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static void random_velocity(struct ball * p) {
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void random_velocity(struct ball * p) {
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double r2;
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do {
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p->v_x = v_min + rand() % (v_max + 1 - v_min);
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@ -72,7 +70,7 @@ void balls_init_state () {
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}
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}
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static void ball_collision (struct ball * p, struct ball * q) {
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void ball_collision (struct ball * p, struct ball * q) {
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double dx = q->x - p->x;
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double dy = q->y - p->y;
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double d2 = dx*dx + dy*dy;
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@ -134,14 +132,191 @@ void movement_and_borders () {
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ball_update_state(balls + i);
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}
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void check_collisions () {
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/* Collision check with index
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*/
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struct rectangle {
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double min_x; /* left */
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double min_y; /* bottom */
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double max_x; /* right */
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double max_y; /* top */
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};
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struct bt_node {
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struct ball * ball;
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struct rectangle r;
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struct bt_node * left;
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struct bt_node * right;
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};
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struct bt_node * c_index = 0;
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static struct bt_node * c_index_init_node(struct bt_node * n, struct ball * b) {
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n->ball = b;
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n->r.min_x = b->x - b->radius;
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n->r.min_y = b->y - b->radius;
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n->r.max_x = b->x + b->radius;
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n->r.max_y = b->y + b->radius;
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n->left = 0;
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n->right = 0;
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return n;
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}
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static void c_index_add_ball(struct bt_node * n, const struct ball * b) {
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if (n->r.min_x > b->x - b->radius)
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n->r.min_x = b->x - b->radius;
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if (n->r.min_y > b->y - b->radius)
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n->r.min_y = b->y - b->radius;
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if (n->r.max_x < b->x + b->radius)
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n->r.max_x = b->x + b->radius;
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if (n->r.max_y < b->y + b->radius)
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n->r.max_y = b->y + b->radius;
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}
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static void c_index_insert(struct bt_node * t, struct bt_node * n, struct ball * b) {
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assert(t);
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double w = width;
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double h = height;
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double ref_x = 0.0;
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double ref_y = 0.0;
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for (;;) {
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c_index_add_ball(t, b);
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if (w > h) { /* horizontal split */
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if (b->x <= t->ball->x) {
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if (t->left) {
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w = t->ball->x - ref_x;
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t = t->left;
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} else {
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t->left = c_index_init_node(n, b);
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return;
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}
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} else {
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if (t->right) {
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w -= t->ball->x - ref_x;
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ref_x = t->ball->x;
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t = t->right;
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} else {
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t->right = c_index_init_node(n, b);
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return;
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}
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}
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} else { /* vertical split */
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if (b->y <= t->ball->y) {
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if (t->left) {
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h = t->ball->y - ref_y;
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t = t->left;
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} else {
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t->left = c_index_init_node(n, b);
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return;
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}
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} else {
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if (t->right) {
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h -= t->ball->y - ref_y;
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ref_y = t->ball->y;
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t = t->right;
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} else {
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t->right = c_index_init_node(n, b);
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return;
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}
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}
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}
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}
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}
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void c_index_build() {
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c_index_init_node(c_index, balls);
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for(int i = 1; i < n_balls; ++i) {
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c_index_insert(c_index, c_index + i, balls + i);
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}
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}
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struct bt_node ** c_index_stack = 0;
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unsigned int c_index_stack_top = 0;
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void c_index_stack_clear() {
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c_index_stack_top = 0;
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}
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static void c_index_stack_push(struct bt_node * n) {
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c_index_stack[c_index_stack_top++] = n;
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}
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static struct bt_node * c_index_stack_pop() {
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if (c_index_stack_top > 0)
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return c_index_stack[--c_index_stack_top];
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else
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return 0;
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}
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static int c_index_ball_in_rectangle(const struct bt_node * n, const struct ball * b) {
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return n->r.min_x <= b->x + b->radius
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&& n->r.max_x >= b->x - b->radius
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&& n->r.min_y <= b->y + b->radius
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&& n->r.max_y >= b->y - b->radius;
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}
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static int c_index_must_check(const struct bt_node * n, const struct ball * b) {
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return n != 0 && n->ball < b && c_index_ball_in_rectangle(n, b);
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}
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void c_index_check_collisions() {
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for(struct ball * b = balls + 1; b < balls + n_balls; ++b) {
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c_index_stack_clear();
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struct bt_node * n = c_index;
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do {
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ball_collision(n->ball, b);
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if (c_index_must_check(n->left, b)) {
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if (c_index_must_check(n->right, b)) {
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c_index_stack_push(n->right);
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}
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n = n->left;
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} else if (c_index_must_check(n->right, b)) {
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n = n->right;
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} else {
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n = c_index_stack_pop();
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}
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} while (n);
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}
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}
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int c_index_init() {
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if (!c_index)
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c_index = malloc(sizeof(struct bt_node) * n_balls);
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if (!c_index)
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return 0;
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if (!c_index_stack)
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c_index_stack = malloc(sizeof(struct bt_node *) * n_balls);
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if (!c_index_stack)
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return 0;
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return 1;
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}
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void c_index_destroy() {
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if (c_index)
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free(c_index);
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if (c_index_stack)
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free(c_index_stack);
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c_index = 0;
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c_index_stack = 0;
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}
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/* Trivial collision check
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*/
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void check_collisions_simple () {
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for(int i = 0; i < n_balls; ++i)
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for(int j = i + 1; j < n_balls; ++j)
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ball_collision(balls + i, balls + j);
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}
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static void update_state () {
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if (collisions)
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void check_collisions_with_index () {
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c_index_build();
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c_index_check_collisions();
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}
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void (*check_collisions)() = 0;
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void update_state () {
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if (check_collisions)
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check_collisions();
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movement_and_borders();
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}
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@ -149,13 +324,13 @@ static void update_state () {
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/* Graphics System
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*/
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static GtkWidget * window;
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static cairo_t * cr = 0;
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GtkWidget * window;
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cairo_t * cr = 0;
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static int gravity_vector_countdown = 0;
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static int gravity_vector_init = 300;
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int gravity_vector_countdown = 0;
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int gravity_vector_init = 300;
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static void draw_gravity_vector() {
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void draw_gravity_vector() {
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if (gravity_vector_countdown != 0) {
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cairo_new_path(cr);
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cairo_move_to(cr, width/2, height/2);
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@ -170,10 +345,10 @@ static void draw_gravity_vector() {
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}
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}
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static int balls_graphics_initialized = 0;
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int balls_graphics_initialized = 0;
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const char * face_filename = 0;
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static void init_graphics() {
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void init_graphics() {
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if (cr)
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cairo_destroy(cr);
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cr = gdk_cairo_create(window->window);
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@ -223,7 +398,7 @@ static void init_graphics() {
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balls_graphics_initialized = 1;
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}
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static void destroy_graphics() {
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void destroy_graphics() {
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if (cr) {
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cairo_destroy(cr);
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cr = 0;
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@ -235,7 +410,7 @@ static void destroy_graphics() {
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}
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}
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static void draw_balls_onto_window () {
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void draw_balls_onto_window () {
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/* clear pixmap */
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cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, clear_alpha);
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cairo_paint(cr);
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@ -252,7 +427,7 @@ static void draw_balls_onto_window () {
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}
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}
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static gint resize_event (GtkWidget *widget, GdkEventConfigure * event) {
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gint resize_event (GtkWidget *widget, GdkEventConfigure * event) {
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if (width == widget->allocation.width && height == widget->allocation.height)
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return FALSE;
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@ -265,7 +440,7 @@ static gint resize_event (GtkWidget *widget, GdkEventConfigure * event) {
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return TRUE;
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}
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static gint keyboard_input (GtkWidget *widget, GdkEventKey *event) {
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gint keyboard_input (GtkWidget *widget, GdkEventKey *event) {
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if (event->type != GDK_KEY_PRESS)
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return FALSE;
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switch(event->keyval) {
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@ -299,15 +474,15 @@ static gint keyboard_input (GtkWidget *widget, GdkEventKey *event) {
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return TRUE;
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}
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static void show_event (GtkWidget *widget, gpointer data) {
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void show_event (GtkWidget *widget, gpointer data) {
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init_graphics();
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}
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static gboolean expose_event (GtkWidget *widget, GdkEventExpose *event, gpointer data) {
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gboolean expose_event (GtkWidget *widget, GdkEventExpose *event, gpointer data) {
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return TRUE;
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}
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static void destroy_window (void) {
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void destroy_window (void) {
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gtk_main_quit();
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}
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@ -325,11 +500,11 @@ void print_usage (const char * progname) {
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"\tface=<filename>\n"
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"\tclear=<clear-alpha>\n"
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"\t-v :: enables rendering timing statitstics\n"
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"\t-c :: disables ball-ball collisions\n",
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"\tcollisions=<C> :: n=no collisions, s=simple, i=index\n",
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progname);
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}
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static int rendering_statistics = 0;
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int rendering_statistics = 0;
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gboolean timeout (gpointer user_data) {
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guint64 start = 0, elapsed_usec;
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@ -385,9 +560,23 @@ int main (int argc, const char *argv[]) {
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rendering_statistics = 1;
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continue;
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}
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if (strcmp(argv[i], "-c") == 0) {
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collisions = 0;
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char collisions;
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if (sscanf(argv[i], "collisions=%c", &collisions) == 1) {
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switch (collisions) {
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case 'i':
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case 'I':
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check_collisions = check_collisions_with_index;
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continue;
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case '0':
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case 'N':
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case 'n':
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check_collisions = 0;
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continue;
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case 's':
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case 'S':
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check_collisions = check_collisions_simple;
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continue;
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}
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}
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print_usage(argv[0]);
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return 1;
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@ -396,6 +585,8 @@ int main (int argc, const char *argv[]) {
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balls = malloc(sizeof(struct ball)*n_balls);
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assert(balls);
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assert(c_index_init());
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balls_init_state();
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gtk_init(0, 0);
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@ -424,6 +615,7 @@ int main (int argc, const char *argv[]) {
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printf("\n");
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destroy_graphics();
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c_index_destroy();
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free(balls);
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return 0;
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