From 89ef496eab23a798fcd771bb50bbde7392ca360e Mon Sep 17 00:00:00 2001
From: Marco Thomas <mthomas@marcmk.de>
Date: Mon, 24 Aug 2020 23:37:09 +0200
Subject: [PATCH] Add Basic Movement, Add Food generation

---
 src/main.rs | 128 ++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 115 insertions(+), 13 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 0d3acaf..fb13e8e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,14 +9,26 @@ use piston::event_loop::*;
 use glutin_window::GlutinWindow;
 use opengl_graphics::{GlGraphics, OpenGL};
 
+const PIXEL_SIZE: i32 = 20;
+const FIELD_SIZE_X: i32 = 30;
+const FIELD_SIZE_Y: i32 = 30;
+
+#[derive(Clone, PartialEq)]
+enum Direction {
+    Up,
+    Down,
+    Left,
+    Right,
+}
+
 struct Game {
     gl: GlGraphics,
     snake: Snake,
+    food: Food,
 }
 
 impl Game {
     fn render(&mut self, args: &RenderArgs) {
-        use graphics;
 
         const BLACK: [f32; 4] = [0.0, 0.0, 0.0, 1.0];
 
@@ -25,24 +37,34 @@ impl Game {
         });
 
         self.snake.render(&mut self.gl, args);
+
+        self.food.render(&mut self.gl, args);
+    }
+
+    fn update(&mut self) {
+        self.snake.update();
+    }
+
+    fn button_press(&mut self, button: &Button) {
+        self.snake.change_direction(&button);
     }
 }
 
 struct Snake {
-    x_pos: i32,
-    y_pos: i32,
+    pos_x: i32,
+    pos_y: i32,
+    direction: Direction,
 }
 
 impl Snake {
     fn render(&self, gl: &mut GlGraphics, args: &RenderArgs) {
-        use graphics;
 
         const GREEN: [f32; 4] = [0.0, 1.0, 0.0, 1.0];
 
         let square = graphics::rectangle::square(
-            self.x_pos as f64,
-            self.y_pos as f64,
-            20.0);
+            (self.pos_x * PIXEL_SIZE) as f64,
+            (self.pos_y * PIXEL_SIZE) as f64,
+            PIXEL_SIZE as f64);
 
         gl.draw(args.viewport(), |c, gl| {
             let transform = c.transform;
@@ -50,6 +72,70 @@ impl Snake {
             graphics::rectangle(GREEN, square, transform, gl);
         });
     }
+
+    fn update(&mut self) {
+        match self.direction {
+            Direction::Up => self.pos_y -=1,
+            Direction::Down => self.pos_y +=1,
+            Direction::Left => self.pos_x -=1,
+            Direction::Right => self.pos_x +=1,
+        }
+
+        if self.pos_x > FIELD_SIZE_X {
+            self.pos_x = 0;
+        } else if self.pos_x < 0 {
+            self.pos_x = FIELD_SIZE_X;
+        }
+
+        if self.pos_y > FIELD_SIZE_Y {
+            self.pos_y = 0;
+        } else if self.pos_y < 0 {
+            self.pos_y = FIELD_SIZE_Y;
+        }
+
+    }
+
+    fn change_direction(&mut self, button: &Button) {
+        let last_direction = self.direction.clone();
+
+        self.direction = match button {
+            Button::Keyboard(Key::W) => Direction::Up,
+            Button::Keyboard(Key::S) => Direction::Down,
+            Button::Keyboard(Key::A) => Direction::Left,
+            Button::Keyboard(Key::D) => Direction::Right,
+            _ => last_direction,
+        }
+    }
+}
+
+struct Food {
+    pos_x: i32,
+    pos_y: i32,
+}
+
+impl Food {
+    fn new() -> Food {
+        let random_x: i32 = 3;
+        let random_y: i32 = 3;
+
+        Food { pos_x: random_x, pos_y: random_y }
+    }
+
+    fn render(&self, gl: &mut GlGraphics, args: &RenderArgs) {
+
+        const RED: [f32; 4] = [1.0, 0.0, 0.0, 1.0];
+
+        let square = graphics::rectangle::square(
+            (self.pos_x * PIXEL_SIZE) as f64,
+            (self.pos_y * PIXEL_SIZE) as f64,
+            PIXEL_SIZE as f64);
+
+        gl.draw(args.viewport(), |c, gl| {
+            let transform = c.transform;
+
+            graphics::rectangle(RED, square, transform, gl);
+        });
+    }
 }
 
 fn main() {
@@ -57,7 +143,8 @@ fn main() {
 
     let mut window: GlutinWindow = WindowSettings::new(
         "snake-rs",
-        [200, 200])
+        [(FIELD_SIZE_X * PIXEL_SIZE) as f64,
+        (FIELD_SIZE_Y * PIXEL_SIZE) as f64])
         .graphics_api(opengl)
         .exit_on_esc(true)
         .build()
@@ -66,16 +153,31 @@ fn main() {
     let mut game = Game {
         gl: GlGraphics::new(opengl),
         snake: Snake {
-            x_pos: 50,
-            y_pos: 50
+            pos_x: 0,
+            pos_y: 0,
+            direction: Direction::Right,
         },
+        food: Food::new(),
     };
 
 
-    let mut events = Events::new(EventSettings::new());
+    let mut events = Events::new(EventSettings::new())
+        .max_fps(60)
+        .ups(10);
     while let Some(e) = events.next(&mut window) {
-        if let Some(args) = e.render_args() {
-            game.render(&args);
+
+        if let Some(r) = e.render_args() {
+            game.render(&r);
+        }
+
+        if let Some(_u) = e.update_args() {
+            game.update();
+        }
+
+        if let Some(b) = e.button_args() {
+            if b.state == ButtonState::Press {
+                game.button_press(&b.button);
+            }
         }
     }
 }