draw dots only if mouse moved more than trashold

diff --git a/trace-path.pl b/trace-path.pl
index 8232a2a..9a27b35 100755 (executable)
--- a/trace-path.pl
+++ b/trace-path.pl
@@ -13,6 +13,7 @@ use Carp qw/confess/;
 use Data::Dump qw/dump/;
 
 my ( $w, $h ) = ( 800, 480 );
+my $mouse_trashold = 10;
 
 our $app = SDL::App->new(
        -width  => $w,
@@ -28,6 +29,8 @@ our $mouse_down = 0;
 
 our $white = SDL::Color->new( 0xff, 0xff, 0xff );
 
+my ( $last_x, $last_y ) = ( 0,0 );
+
 sub handle_events {
 
        while ( $event->wait ) {
@@ -48,11 +51,16 @@ sub handle_events {
                        warn "key up ", $event->key_name,$/;
                } elsif ( $type == SDL_MOUSEMOTION() ) {
 #                      warn "mouse ", $event->motion_xrel, ' ', $event->motion_yrel;
-                       warn "mouse $mouse_down @ ", $event->motion_x, ' ', $event->motion_y;
-                       if ( $mouse_down ) {
+                       my ( $x, $y ) = ( $event->motion_x, $event->motion_y );
+                       warn "mouse $mouse_down @ $x*$y\n";
+                       my $dx = abs( $last_x - $x );
+                       my $dy = abs( $last_y - $y );
+                       if ( $mouse_down && ( $dx > $mouse_trashold || $dy > $mouse_trashold ) ) {
                                my $rect = SDL::Rect->new( -x => $event->motion_x, -y => $event->motion_y, -w => 3, -h => 3 );
                                $app->fill( $rect, $white );
                                $app->update( $rect );
+                               $last_x = $x;
+                               $last_y = $y;
                        }
                } else {
                        warn "unknown $type\n";