we got jumping

src/main.rs

@@ -3,7 +3,7 @@ extern crate sdl2;
 
 use sdl2::video::{Window, WindowPos, OPENGL};
 use sdl2::event::{poll_event, Event};
-use sdl2::timer::{get_ticks, delay};
+use sdl2::timer::{get_ticks};
 use sdl2::rect::{Rect};
 
 
@@ -27,9 +27,15 @@ fn main() {
     };
         
     let mut player = Rect::new(0, 290, 10, 10);
-
+    
     let mut x : f32 = 390.0;
+    let mut y : f32 = 290.0;
+
     let mut v_x : f32 = 0.0;
+    let mut v_y : f32 = 0.0;
+
+    let mut on_ground = true;
+    let mut gravity : f32 = 0.3;
     
     let mut current : uint = 0;
     let mut elapsed : uint = 0;
@@ -49,9 +55,15 @@ fn main() {
                 if key == sdl2::keycode::KeyCode::Escape {
                     break 'event;
                 } else if key == sdl2::keycode::KeyCode::Right {
-                    v_x = 1.0;
+                    v_x = 4.0;
                 } else if key == sdl2::keycode::KeyCode::Left {
-                    v_x = -1.0;
+                    v_x = -4.0;
+                } else if key == sdl2::keycode::KeyCode::Up {
+                    if on_ground {
+                        v_y = -8.0;
+                        
+                        on_ground = false;
+                    }
                 }
             },
             Event::KeyUp(_, _, key, _, _, _) => {
@@ -59,13 +71,27 @@ fn main() {
                     v_x = 0.0;
                 } else if key == sdl2::keycode::KeyCode::Left {
                     v_x = 0.0;
+                } else if key == sdl2::keycode::KeyCode::Up {
+                    if v_y < -4.0 {
+                        v_y = -4.0;
+                    }
                 }
             },
             _ => (),
         }
         
         while lag >= MS_PER_UPDATE {
+            v_y += gravity;
+            
             x += v_x;
+            y += v_y;
+
+            if y > 290.0 {
+                y = 290.0;
+                v_y = 0.0;
+                
+                on_ground = true;
+            }
 
             lag -= MS_PER_UPDATE;
         }
@@ -74,6 +100,7 @@ fn main() {
         let _ = renderer.clear();
 
         player.x = x as i32;
+        player.y = y as i32;
         
         let _ = renderer.set_draw_color(sdl2::pixels::Color::RGB(0, 255, 0));
         let _ = renderer.fill_rect(&player);