basic, independent, constant-speed rotation.
This commit is contained in:
Antonio Carzaniga
parent
300e71cbde
commit
76bb057e6c
97
balls.c
97
balls.c
@ -18,7 +18,11 @@ struct ball {
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double v_x;
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double v_y;
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cairo_surface_t * surface;
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unsigned int rotation_steps;
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double angle;
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double v_angle;
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cairo_surface_t ** faces;
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};
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double delta = 0.01; /* seconds */
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@ -32,6 +36,9 @@ unsigned int radius_max = 10;
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unsigned int v_max = 100;
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unsigned int v_min = 0;
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unsigned int v_angle_min = 0;
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unsigned int v_angle_max = 100;
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struct ball * balls = 0;
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unsigned int n_balls = 50;
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@ -64,6 +71,9 @@ void balls_init_state () {
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if (rand() % 2)
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balls[i].v_y = -balls[i].v_y;
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balls[i].radius = radius_min + rand() % (radius_max + 1 - radius_min);
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unsigned int v_angle_360 = (v_angle_min + rand() % (v_angle_max + 1 - v_angle_min)) % 360;
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balls[i].v_angle = 2*M_PI*v_angle_360/360;
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balls[i].angle = (rand() % 360)*2*M_PI/360;
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}
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}
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@ -122,6 +132,9 @@ void ball_update_state (struct ball * p) {
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p->v_y = -p->v_y;
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}
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}
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p->angle += delta*p->v_angle;
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if (p->angle >= 2*M_PI)
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p->angle -= 2*M_PI;
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}
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void movement_and_borders () {
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@ -342,51 +355,65 @@ void draw_gravity_vector(cairo_t * cr) {
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const char * face_filename = 0;
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void init_graphics() {
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cairo_surface_t * face_surface;
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int face_x_offset, face_y_offset;
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static const double linear_rotation_unit = 2.0;
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if (face_filename) {
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face_surface = cairo_image_surface_create_from_png (face_filename);
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switch (cairo_surface_status(face_surface)) {
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case CAIRO_STATUS_SUCCESS:
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face_x_offset = cairo_image_surface_get_width (face_surface) / 2;
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face_y_offset = cairo_image_surface_get_height (face_surface) / 2;
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break;
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default:
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cairo_surface_destroy (face_surface);
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face_surface = 0;
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fprintf(stderr, "could not create surface from PNG file %s\n", face_filename);
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void init_ball_face(struct ball * b, cairo_surface_t * face) {
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if (face) {
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b->rotation_steps = 2*M_PI * b->radius / linear_rotation_unit;
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} else {
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b->rotation_steps = 1;
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}
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} else
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face_surface = 0;
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for(int i = 0; i < n_balls; ++i) {
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balls[i].surface = gdk_window_create_similar_surface(window->window,
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b->faces = malloc(sizeof(cairo_surface_t *)*b->rotation_steps);
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assert(b->faces);
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for (int i = 0; i < b->rotation_steps; ++i) {
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b->faces[i] = gdk_window_create_similar_surface(window->window,
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CAIRO_CONTENT_COLOR_ALPHA,
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2*balls[i].radius, 2*balls[i].radius);
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cairo_t * ball_cr = cairo_create(balls[i].surface);
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cairo_translate(ball_cr, balls[i].radius, balls[i].radius);
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cairo_arc(ball_cr, 0.0, 0.0, balls[i].radius, 0, 2 * M_PI);
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2*b->radius, 2*b->radius);
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assert(b->faces[i]);
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cairo_t * ball_cr = cairo_create(b->faces[i]);
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cairo_translate(ball_cr, b->radius, b->radius);
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cairo_arc(ball_cr, 0.0, 0.0, b->radius, 0, 2 * M_PI);
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cairo_clip(ball_cr);
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cairo_set_source_rgb(ball_cr, 1.0*(rand() % 256)/255, 1.0*(rand() % 256)/255, 1.0*(rand() % 256)/255);
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cairo_paint(ball_cr);
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if (face_surface) {
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cairo_scale (ball_cr, 1.0 * balls[i].radius / face_x_offset, 1.0 * balls[i].radius / face_y_offset);
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cairo_set_source_surface(ball_cr, face_surface, -face_x_offset, -face_y_offset);
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if (face) {
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int face_x_offset = cairo_image_surface_get_width (face) / 2;
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int face_y_offset = cairo_image_surface_get_height (face) / 2;
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cairo_rotate(ball_cr, i*2*M_PI/b->rotation_steps);
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cairo_scale (ball_cr, 1.0 * b->radius / face_x_offset, 1.0 * b->radius / face_y_offset);
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cairo_set_source_surface(ball_cr, face, -face_x_offset, -face_y_offset);
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cairo_paint(ball_cr);
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}
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cairo_surface_flush(balls[i].surface);
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cairo_surface_flush(b->faces[i]);
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cairo_destroy(ball_cr);
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}
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}
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void init_graphics() {
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cairo_surface_t * face_surface = 0;
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if (face_filename) {
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face_surface = cairo_image_surface_create_from_png (face_filename);
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if (cairo_surface_status(face_surface) != CAIRO_STATUS_SUCCESS) {
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cairo_surface_destroy (face_surface);
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face_surface = 0;
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fprintf(stderr, "could not create surface from PNG file %s\n", face_filename);
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}
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}
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for(int i = 0; i < n_balls; ++i)
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init_ball_face(&(balls[i]), face_surface);
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if (face_surface)
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cairo_surface_destroy (face_surface);
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}
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void destroy_graphics() {
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for(int i = 0; i < n_balls; ++i)
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cairo_surface_destroy(balls[i].surface);
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for(int i = 0; i < n_balls; ++i) {
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for (int j = 0; j < balls[i].rotation_steps; ++i)
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cairo_surface_destroy(balls[i].faces[j]);
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free(balls[i].faces);
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}
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}
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void draw_balls_onto_window () {
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@ -401,7 +428,15 @@ void draw_balls_onto_window () {
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for(int i = 0; i < n_balls; ++i) {
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cairo_save(cr);
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cairo_translate(cr, balls[i].x - balls[i].radius, balls[i].y - balls[i].radius);
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cairo_set_source_surface(cr, balls[i].surface, 0, 0);
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unsigned int face_id;
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if (balls[i].rotation_steps == 1)
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face_id = 0;
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else {
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face_id = balls[i].rotation_steps*balls[i].angle/M_PI;
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if (face_id >= balls[i].rotation_steps)
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face_id %= balls[i].rotation_steps;
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}
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cairo_set_source_surface(cr, balls[i].faces[face_id], 0, 0);
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cairo_paint(cr);
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cairo_restore(cr);
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}
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