Simple snake movement mechanic demonstration for a friend

C++/snake-movement-mechanic/main.cpp

@@ -0,0 +1,125 @@
+#define OLC_PGE_APPLICATION
+#include "olcPixelGameEngine.h"
+
+#include <iostream>
+#include <vector>
+
+const int MAP_WIDTH = 40;
+const int MAP_HEIGHT = 40;
+
+struct Point {
+    int x, y;
+    bool isSnake;
+};
+
+typedef enum {
+    DIRECTION_UP,
+    DIRECTION_RIGHT,
+    DIRECTION_DOWN,
+    DIRECTION_LEFT
+} SnakeDir;
+
+int index(int x, int y) {
+    return y * MAP_HEIGHT + x; 
+}
+
+class Snake : public olc::PixelGameEngine {
+public:
+    std::vector<Point> map;
+    std::vector<Point> snake_stack;
+    SnakeDir dir = DIRECTION_RIGHT;
+
+    bool OnUserCreate() {
+        // Loop over every point in the map column
+        // by column and initialize them as points
+        // in the 1d map vector
+        for (int i = 0; i < MAP_WIDTH; i++) {
+            for (int j = 0; j < MAP_HEIGHT; j++) {
+                map.push_back({i, j, false});
+            }
+        }
+
+        // Settup snake stack
+        snake_stack.push_back({2, 3, true});
+        snake_stack.push_back({3, 3, true});
+        snake_stack.push_back({4, 3, true});
+        snake_stack.push_back({5, 3, true});
+        dir = DIRECTION_RIGHT;
+
+        return true;
+    }
+
+    bool OnUserUpdate(float fElapsedTime) {
+        // Take input and change direction
+        if (GetKey(olc::Key::W).bPressed)
+            dir = DIRECTION_UP;
+        if (GetKey(olc::Key::A).bPressed)
+            dir = DIRECTION_LEFT;
+        if (GetKey(olc::Key::S).bPressed)
+            dir = DIRECTION_DOWN;
+        if (GetKey(olc::Key::D).bPressed)
+            dir = DIRECTION_RIGHT;
+
+        // Push an element for the head 
+        // dependant on the direction
+
+        if (dir == DIRECTION_UP) {
+            snake_stack.push_back({snake_stack.back().x, snake_stack.back().y - 1, true});
+        }
+        
+        if (dir == DIRECTION_RIGHT) {
+            snake_stack.push_back({snake_stack.back().x + 1, snake_stack.back().y, true});
+        }
+
+        if (dir == DIRECTION_DOWN) {
+            snake_stack.push_back({snake_stack.back().x, snake_stack.back().y + 1, true});
+        }
+
+        if (dir == DIRECTION_LEFT) {
+            snake_stack.push_back({snake_stack.back().x - 1, snake_stack.back().y, true});
+        }
+
+        // Pop last element of the tail
+
+        snake_stack.erase(snake_stack.begin());
+
+        updateSnake();
+        draw();
+        return true;
+    }
+
+    void updateSnake() {
+        // Set every map point to no snake
+        for (int i = 0; i < map.size(); i++) {
+            map[i].isSnake = false;
+        }
+
+        // Set the points that the snake are in in the map
+        // to have a snake in
+        for (int i = 0; i < snake_stack.size(); i++) {
+            map[index(snake_stack[i].x, snake_stack[i].y)].isSnake = true;            
+        }
+    }
+
+    void draw() {
+        // Loop over every element in the map
+        // and draw them on the map in their respective
+        // screen position
+        for (int i = 0; i < MAP_WIDTH; i++) {
+            for (int j = 0; j < MAP_HEIGHT; j++) {
+                if (map[index(i, j)].isSnake) {
+                    DrawRect(i, j, 1, 1, olc::RED);
+                } else {
+                    DrawRect(i, j, 1, 1, olc::BLUE);
+                }
+            }
+        }
+    }
+};
+
+int main(int argc, char** argv) {
+    Snake app;
+    app.Construct(MAP_WIDTH, MAP_HEIGHT, 20, 20);
+    app.Start();
+    return 0;
+}