flying-balls/balls.c

269 lines
7.3 KiB
C

#include <stdlib.h>
#include <math.h>
#include <assert.h>
#include "game.h"
#include "balls.h"
#include "gravity.h"
unsigned int radius_min = 5;
unsigned int radius_max = 10;
unsigned int v_max = 100;
unsigned int v_min = 0;
unsigned int v_angle_min = 0;
unsigned int v_angle_max = 100;
struct ball * balls = 0;
unsigned int n_balls = 50;
static void random_velocity(struct ball * p) {
double r2;
do {
p->v_x = v_min + rand() % (v_max + 1 - v_min);
p->v_y = v_min + rand() % (v_max + 1 - v_min);
r2 = p->v_x*p->v_x + p->v_y*p->v_y;
} while (r2 > v_max*v_max || r2 < v_min*v_min);
}
void balls_init_state () {
static const unsigned int border = 10;
unsigned int w = width < 2*border ? 1 : width - 2*border;
unsigned int h = height < 2*border ? 1 : height - 2*border;
for (unsigned int i = 0; i < n_balls; ++i) {
balls[i].x = border + rand() % w;
balls[i].y = border + rand() % h;
random_velocity(balls + i);
if (rand() % 2)
balls[i].v_x = -balls[i].v_x;
if (rand() % 2)
balls[i].v_y = -balls[i].v_y;
balls[i].radius = radius_min + rand() % (radius_max + 1 - radius_min);
unsigned int v_angle_360 = (v_angle_min + rand() % (v_angle_max + 1 - v_angle_min)) % 360;
balls[i].v_angle = 2*M_PI*v_angle_360/360;
balls[i].angle = (rand() % 360)*2*M_PI/360;
}
}
void ball_update_state (struct ball * p) {
p->x += delta*p->v_x + delta*delta*g_x/2.0;
p->v_x += delta*g_x;
p->y += delta*p->v_y + delta*delta*g_y/2.0;
p->v_y += delta*g_y;
if (p->x + p->radius > width) { /* right wall */
if (p->v_x > 0) {
p->x -= p->x + p->radius - width;
p->v_x = -p->v_x;
}
} else if (p->x < p->radius) { /* left wall */
if (p->v_x < 0) {
p->x += p->radius - p->x;
p->v_x = -p->v_x;
}
}
if (p->y + p->radius > height) { /* bottom wall */
if (p->v_y > 0) {
p->y -= p->y + p->radius - height;
p->v_y = -p->v_y;
}
} else if (p->y < p->radius) { /* top wall */
if (p->v_y < 0) {
p->y += p->radius - p->y;
p->v_y = -p->v_y;
}
}
p->angle += delta*p->v_angle;
while (p->angle >= 2*M_PI)
p->angle -= 2*M_PI;
while (p->angle < 0)
p->angle += 2*M_PI;
}
void ball_elastic_collision (struct ball * p, struct ball * q) {
double dx = q->x - p->x;
double dy = q->y - p->y;
double d2 = dx*dx + dy*dy;
double r = p->radius + q->radius;
if (d2 <= r*r) {
double dv_x = q->v_x - p->v_x;
double dv_y = q->v_y - p->v_y;
double mp = p->radius * p->radius;
double mq = q->radius * q->radius;
double f = dv_x*dx + dv_y*dy;
if (f < 0) {
f /= d2*(mp + mq);
p->v_x += 2*mq*f*dx;
p->v_y += 2*mq*f*dy;
q->v_x -= 2*mp*f*dx;
q->v_y -= 2*mp*f*dy;
}
}
}
void ball_reposition (struct ball * b) {
if (b->x < b->radius)
b->x = b->radius;
else if (b->x + b->radius > width)
b->x = width - b->radius;
if (b->y < b->radius)
b->y = b->radius;
else if (b->y + b->radius > height)
b->y = height - b->radius;
}
const char * face_filename = 0;
int face_rotation = 0;
static const double linear_rotation_unit = 2.0;
static unsigned int faces_count;
static struct ball_face ** faces;
struct ball_face {
unsigned int rotations;
cairo_surface_t ** c_faces;
};
static double random_color_component() {
return 1.0*(rand() % 200 + 56)/255;
};
static struct ball_face * new_ball_face(unsigned int radius, cairo_surface_t * face, int rotation) {
struct ball_face * f = malloc(sizeof(struct ball_face));
if (!f)
return 0;
if (face && rotation) {
f->rotations = 2*M_PI * radius / linear_rotation_unit;
} else {
f->rotations = 1;
}
f->c_faces = malloc(sizeof(cairo_surface_t *)*f->rotations);
if (!f->c_faces) {
free(f);
return 0;
}
for (int i = 0; i < f->rotations; ++i) {
f->c_faces[i] = gdk_window_create_similar_surface(gtk_widget_get_window(canvas),
CAIRO_CONTENT_COLOR_ALPHA,
2*radius, 2*radius);
assert(f->c_faces[i]);
cairo_t * ball_cr = cairo_create(f->c_faces[i]);
cairo_translate(ball_cr, radius, radius);
cairo_arc(ball_cr, 0.0, 0.0, radius, 0, 2 * M_PI);
cairo_clip(ball_cr);
if (face) {
int face_x_offset = cairo_image_surface_get_width (face) / 2;
int face_y_offset = cairo_image_surface_get_height (face) / 2;
cairo_rotate(ball_cr, i*2*M_PI/f->rotations);
cairo_scale (ball_cr, 1.0 * radius / face_x_offset, 1.0 * radius / face_y_offset);
cairo_set_source_surface(ball_cr, face, -face_x_offset, -face_y_offset);
cairo_paint(ball_cr);
} else {
cairo_pattern_t *pat;
pat = cairo_pattern_create_radial (-0.2*radius, -0.2*radius, 0.2*radius,
-0.2*radius, -0.2*radius, 1.3*radius);
double col_r = random_color_component();
double col_g = random_color_component();
double col_b = random_color_component();
cairo_pattern_add_color_stop_rgba (pat, 0, col_r, col_g, col_b, 1);
cairo_pattern_add_color_stop_rgba (pat, 1, col_r/3, col_g/3, col_b/3, 1);
cairo_set_source (ball_cr, pat);
cairo_arc (ball_cr, 0.0, 0.0, radius, 0, 2 * M_PI);
cairo_fill (ball_cr);
}
cairo_surface_flush(f->c_faces[i]);
cairo_destroy(ball_cr);
}
return f;
}
static void balls_init_faces () {
cairo_surface_t * face_surface = 0;
if (face_filename) {
face_surface = cairo_image_surface_create_from_png (face_filename);
if (cairo_surface_status(face_surface) != CAIRO_STATUS_SUCCESS) {
cairo_surface_destroy (face_surface);
face_surface = 0;
fprintf(stderr, "could not create surface from PNG file %s\n", face_filename);
}
}
if (face_surface) {
faces_count = radius_max + 1 - radius_min;
faces = malloc(sizeof(struct ball_face *)*faces_count);
for (unsigned int i = 0; i < faces_count; ++i)
faces[i] = 0;
for(struct ball * b = balls; b != balls + n_balls; ++b) {
unsigned int r_idx = b->radius - radius_min;
if (!faces[r_idx])
faces[r_idx] = new_ball_face(b->radius, face_surface, face_rotation);
b->face = faces[r_idx];
}
cairo_surface_destroy (face_surface);
} else {
faces_count = n_balls;
faces = malloc(sizeof(struct ball_face *)*faces_count);
for (unsigned int i = 0; i < n_balls; ++i)
balls[i].face = faces[i] = new_ball_face(balls[i].radius, 0, face_rotation);
}
}
void balls_draw (cairo_t * cr) {
for (const struct ball * b = balls; b != balls + n_balls; ++b) {
cairo_save(cr);
cairo_translate(cr, b->x - b->radius, b->y - b->radius);
unsigned int face_id;
if (b->face->rotations == 1)
face_id = 0;
else {
face_id = b->face->rotations*b->angle/(2*M_PI);
assert(face_id < b->face->rotations);
if (face_id >= b->face->rotations)
face_id %= b->face->rotations;
}
cairo_set_source_surface(cr, b->face->c_faces[face_id], 0, 0);
cairo_paint(cr);
cairo_restore(cr);
}
}
static void balls_destroy_faces () {
if (!faces)
return;
for (int i = 0; i < faces_count; ++i) {
if (faces[i]) {
if (faces[i]->c_faces) {
for (unsigned int j = 0; j < faces[i]->rotations; ++j)
cairo_surface_destroy(faces[i]->c_faces[j]);
free(faces[i]->c_faces);
}
free(faces[i]);
}
}
free (faces);
faces = 0;
faces_count = 0;
}
void balls_destroy () {
balls_destroy_faces ();
free (balls);
}
void balls_init () {
balls = malloc(sizeof(struct ball)*n_balls);
assert(balls);
balls_init_state ();
balls_init_faces ();
}