karma/flying-balls
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basic, independent, constant-speed rotation.

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This commit is contained in:
Antonio Carzaniga 2019-12-18 21:18:21 +01:00
parent 300e71cbde
commit 76bb057e6c
1 changed files with 68 additions and 33 deletions
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101
balls.c
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@ -18,7 +18,11 @@ struct ball {
double v_x; double v_x;
double v_y; double v_y;
cairo_surface_t * surface; unsigned int rotation_steps;
double angle;
double v_angle;
cairo_surface_t ** faces;
}; };
double delta = 0.01; /* seconds */ double delta = 0.01; /* seconds */
@ -32,6 +36,9 @@ unsigned int radius_max = 10;
unsigned int v_max = 100; unsigned int v_max = 100;
unsigned int v_min = 0; unsigned int v_min = 0;
unsigned int v_angle_min = 0;
unsigned int v_angle_max = 100;
struct ball * balls = 0; struct ball * balls = 0;
unsigned int n_balls = 50; unsigned int n_balls = 50;
@ -64,6 +71,9 @@ void balls_init_state () {
if (rand() % 2) if (rand() % 2)
balls[i].v_y = -balls[i].v_y; balls[i].v_y = -balls[i].v_y;
balls[i].radius = radius_min + rand() % (radius_max + 1 - radius_min); 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;
} }
} }
@ -122,6 +132,9 @@ void ball_update_state (struct ball * p) {
p->v_y = -p->v_y; p->v_y = -p->v_y;
} }
} }
p->angle += delta*p->v_angle;
if (p->angle >= 2*M_PI)
p->angle -= 2*M_PI;
} }
void movement_and_borders () { void movement_and_borders () {
@ -342,51 +355,65 @@ void draw_gravity_vector(cairo_t * cr) {
const char * face_filename = 0; const char * face_filename = 0;
void init_graphics() { static const double linear_rotation_unit = 2.0;
cairo_surface_t * face_surface;
int face_x_offset, face_y_offset;
if (face_filename) { void init_ball_face(struct ball * b, cairo_surface_t * face) {
face_surface = cairo_image_surface_create_from_png (face_filename); if (face) {
switch (cairo_surface_status(face_surface)) { b->rotation_steps = 2*M_PI * b->radius / linear_rotation_unit;
case CAIRO_STATUS_SUCCESS: } else {
face_x_offset = cairo_image_surface_get_width (face_surface) / 2; b->rotation_steps = 1;
face_y_offset = cairo_image_surface_get_height (face_surface) / 2; }
break; b->faces = malloc(sizeof(cairo_surface_t *)*b->rotation_steps);
default: assert(b->faces);
cairo_surface_destroy (face_surface); for (int i = 0; i < b->rotation_steps; ++i) {
face_surface = 0; b->faces[i] = gdk_window_create_similar_surface(window->window,
fprintf(stderr, "could not create surface from PNG file %s\n", face_filename); CAIRO_CONTENT_COLOR_ALPHA,
} 2*b->radius, 2*b->radius);
} else assert(b->faces[i]);
face_surface = 0; cairo_t * ball_cr = cairo_create(b->faces[i]);
cairo_translate(ball_cr, b->radius, b->radius);
for(int i = 0; i < n_balls; ++i) { cairo_arc(ball_cr, 0.0, 0.0, b->radius, 0, 2 * M_PI);
balls[i].surface = gdk_window_create_similar_surface(window->window,
CAIRO_CONTENT_COLOR_ALPHA,
2*balls[i].radius, 2*balls[i].radius);
cairo_t * ball_cr = cairo_create(balls[i].surface);
cairo_translate(ball_cr, balls[i].radius, balls[i].radius);
cairo_arc(ball_cr, 0.0, 0.0, balls[i].radius, 0, 2 * M_PI);
cairo_clip(ball_cr); cairo_clip(ball_cr);
cairo_set_source_rgb(ball_cr, 1.0*(rand() % 256)/255, 1.0*(rand() % 256)/255, 1.0*(rand() % 256)/255); cairo_set_source_rgb(ball_cr, 1.0*(rand() % 256)/255, 1.0*(rand() % 256)/255, 1.0*(rand() % 256)/255);
cairo_paint(ball_cr); cairo_paint(ball_cr);
if (face_surface) { if (face) {
cairo_scale (ball_cr, 1.0 * balls[i].radius / face_x_offset, 1.0 * balls[i].radius / face_y_offset); int face_x_offset = cairo_image_surface_get_width (face) / 2;
cairo_set_source_surface(ball_cr, face_surface, -face_x_offset, -face_y_offset); int face_y_offset = cairo_image_surface_get_height (face) / 2;
cairo_rotate(ball_cr, i*2*M_PI/b->rotation_steps);
cairo_scale (ball_cr, 1.0 * b->radius / face_x_offset, 1.0 * b->radius / face_y_offset);
cairo_set_source_surface(ball_cr, face, -face_x_offset, -face_y_offset);
cairo_paint(ball_cr); cairo_paint(ball_cr);
} }
cairo_surface_flush(balls[i].surface); cairo_surface_flush(b->faces[i]);
cairo_destroy(ball_cr); cairo_destroy(ball_cr);
} }
}
void init_graphics() {
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);
}
}
for(int i = 0; i < n_balls; ++i)
init_ball_face(&(balls[i]), face_surface);
if (face_surface) if (face_surface)
cairo_surface_destroy (face_surface); cairo_surface_destroy (face_surface);
} }
void destroy_graphics() { void destroy_graphics() {
for(int i = 0; i < n_balls; ++i) for(int i = 0; i < n_balls; ++i) {
cairo_surface_destroy(balls[i].surface); for (int j = 0; j < balls[i].rotation_steps; ++i)
cairo_surface_destroy(balls[i].faces[j]);
free(balls[i].faces);
}
} }
void draw_balls_onto_window () { void draw_balls_onto_window () {
@ -401,7 +428,15 @@ void draw_balls_onto_window () {
for(int i = 0; i < n_balls; ++i) { for(int i = 0; i < n_balls; ++i) {
cairo_save(cr); cairo_save(cr);
cairo_translate(cr, balls[i].x - balls[i].radius, balls[i].y - balls[i].radius); cairo_translate(cr, balls[i].x - balls[i].radius, balls[i].y - balls[i].radius);
cairo_set_source_surface(cr, balls[i].surface, 0, 0); unsigned int face_id;
if (balls[i].rotation_steps == 1)
face_id = 0;
else {
face_id = balls[i].rotation_steps*balls[i].angle/M_PI;
if (face_id >= balls[i].rotation_steps)
face_id %= balls[i].rotation_steps;
}
cairo_set_source_surface(cr, balls[i].faces[face_id], 0, 0);
cairo_paint(cr); cairo_paint(cr);
cairo_restore(cr); cairo_restore(cr);
} }