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keyboard-controlled gravity vector

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This commit is contained in:
Antonio Carzaniga 2019-07-28 15:03:27 +02:00
parent e306fffc2a
commit b2c96f75c1
1 changed files with 30 additions and 0 deletions
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30
balls.c
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@ -138,6 +138,17 @@ static void update_state () {
static GtkWidget * window;
static cairo_t * cr = 0;
static void draw_gravity_vector() {
cairo_new_path(cr);
cairo_move_to(cr, width/2, height/2);
cairo_line_to(cr, width/2 + g_x, height/2 + g_y);
cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
cairo_set_line_width(cr, 1.0);
cairo_stroke(cr);
cairo_arc(cr, width/2 + g_x, height/2 + g_y, 3, 0, 2*M_PI);
cairo_fill(cr);
}
static void draw_balls_onto_window () {
if (!cr)
cr = gdk_cairo_create(window->window);
@ -146,6 +157,8 @@ static void draw_balls_onto_window () {
cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
cairo_paint(cr);
draw_gravity_vector();
/* draw balls */
for(int i = 0; i < n_balls; ++i) {
cairo_set_source_rgb(cr,
@ -177,6 +190,23 @@ static gint keyboard_input (GtkWidget *widget, GdkEventKey *event) {
if (event->type != GDK_KEY_PRESS)
return FALSE;
switch(event->keyval) {
case GDK_KEY_Up:
g_y -= 10;
break;
case GDK_KEY_Down:
g_y += 10;
break;
case GDK_KEY_Left:
g_x -= 10;
break;
case GDK_KEY_Right:
g_x += 10;
break;
case GDK_KEY_F:
case GDK_KEY_f:
g_x = rand() % 201 - 100;
g_y = rand() % 201 - 100;
break;
case GDK_KEY_Q:
case GDK_KEY_q:
gtk_main_quit();