first commit

2 files changed, 407 insertions, 0 deletions

diff --git a/src/games/snake/Snake.cpp b/src/games/snake/Snake.cpp
new file mode 100644
index 0000000..9764a9e
--- /dev/null
+++ b/src/games/snake/Snake.cpp
@@ -0,0 +1,345 @@
+#include <games/snake/Snake.hpp>
+#include <imgui.h>
+
+
+Snake::Snake () {
+    m_IsPaused = false;
+    m_IsRunning = true;
+
+    m_DtInSecondsRemaining = 0.0f;
+    m_LastMillisecondsSinceT0 = SDL_GetTicks();
+
+    m_TilesPerSecond = 4.0f;
+    m_Direction = DIRECTION_RIGHT;
+    m_LastAdvancedDirection = DIRECTION_RIGHT;
+
+    m_MapWidth = 16;
+    m_MapHeight = 16;
+    assert(MAX_MAP_WIDTH <= 64); // m_BodyBitmap is uint64_t[]. We can't exceed that!
+    assert(MAX_MAP_HEIGHT <= 64);
+    assert(m_MapWidth <= MAX_MAP_WIDTH);
+    assert(m_MapHeight <= MAX_MAP_WIDTH);
+
+    m_Tail = 0;
+    m_Head = 1;
+    memset(m_BodyBitmap, 0, sizeof(m_BodyBitmap));
+
+    int32_t head_x = m_MapWidth / 2;
+    int32_t head_y = m_MapHeight / 2;
+    m_BodyPositions[0] = {head_x -1, head_y};
+    m_BodyPositions[1] = {head_x, head_y};
+
+    m_Rng = std::mt19937((std::random_device()()));
+    m_Dist = std::uniform_int_distribution<int32_t>(0, m_MapWidth * m_MapHeight - 3);
+
+    SpawnFood();
+    }
+
+bool Snake::Update(std::vector<SDL_Event> &events, RenderGroup &render_group) {
+    uint64_t milliseconds_since_t0 = SDL_GetTicks();
+    uint64_t milliseconds_since_t0_last = m_LastMillisecondsSinceT0;
+    uint64_t dt_in_milliseconds = milliseconds_since_t0 - milliseconds_since_t0_last;
+    float dt_in_seconds = (float)dt_in_milliseconds / 1000.0f;
+    m_LastMillisecondsSinceT0 = milliseconds_since_t0;
+
+
+    V3F32 clear_color = V3F32(0.3f, 0.3f, 0.3f);
+    render_group.SetCameraSize(4.0f, 3.0f);
+    render_group.Clear(clear_color);
+
+
+    for (SDL_Event &event : events) {
+        if (!m_IsRunning) {
+            printf("event loop is running just false\n");
+            return false;
+        }
+        if (m_IsPaused) {
+            ProcessEventDuringPause(event);
+        }
+        else {
+            ProcessEventDuringResume(event);
+        }
+    }
+
+    if (!m_IsPaused) {
+        MaybeMoveSnake(dt_in_seconds);
+    }
+
+
+    Draw(render_group);
+    DoImgui();
+
+    return m_IsRunning;
+}
+
+void Snake::MaybeMoveSnake(float dt_in_seconds) {
+    float dt_in_seconds_to_use = m_DtInSecondsRemaining + dt_in_seconds;
+    float tiles_per_second = m_TilesPerSecond;
+    float seconds_per_tile = 1.0f / tiles_per_second;
+    while (dt_in_seconds_to_use > seconds_per_tile) {
+        V2I32 head_pos = m_BodyPositions[m_Head];
+        V2I32 tail_pos = m_BodyPositions[m_Tail];
+
+
+        // find head_pos
+        if (m_Direction == DIRECTION_UP) {
+            head_pos.y += 1;
+        }
+        else if (m_Direction == DIRECTION_DOWN) {
+            head_pos.y -= 1;
+        }
+        else if (m_Direction == DIRECTION_RIGHT) {
+            head_pos.x += 1;
+        }
+        else if (m_Direction == DIRECTION_LEFT) {
+            head_pos.x -= 1;
+        }
+        if ((head_pos.x < 0 || head_pos.x >= m_MapWidth) ||
+            (head_pos.y < 0 || head_pos.y >= m_MapHeight))
+        {
+            m_IsRunning = false;
+            return;
+        }
+        uint64_t head_bit = 1 << head_pos.x;
+        uint64_t body_bits = m_BodyBitmap[head_pos.y];
+        if (head_pos.y == tail_pos.y) {
+            body_bits &= ~(1 << tail_pos.x);
+        }
+        if (head_bit & body_bits) {
+            m_IsRunning = false;
+            return;
+        }
+
+
+        // advance head
+        int32_t max_positions = sizeof(m_BodyPositions) / sizeof(m_BodyPositions[0]);
+        m_Head += 1;
+        if (m_Head >= max_positions) {
+            m_Head = 0;
+        }
+
+        m_BodyPositions[m_Head] = head_pos;
+        m_BodyBitmap[head_pos.y] |= (1 << head_pos.x);
+
+
+        if (m_BodyPositions[m_Head] == m_FoodPosition) {
+            SpawnFood();
+        }
+        else {
+            // advance tail
+            V2I32 next_tail_pos = m_BodyPositions[m_Tail];
+            m_BodyBitmap[next_tail_pos.y] &= ~(1 << next_tail_pos.x);
+
+            m_Tail += 1;
+            if (m_Tail >= max_positions) {
+                m_Tail = 0;
+            }
+        }
+
+
+        m_LastAdvancedDirection = m_Direction;
+        dt_in_seconds_to_use -= seconds_per_tile;
+    }
+
+
+    m_DtInSecondsRemaining = dt_in_seconds_to_use;
+}
+
+void Snake::ProcessEventDuringPause(SDL_Event &event) {
+    switch (event.type) {
+    case SDL_EVENT_KEY_DOWN: {
+        if (event.key.key == SDLK_ESCAPE) {
+            m_IsPaused = false;
+        }
+    }
+    default:;
+    }
+}
+
+void Snake::ProcessEventDuringResume(SDL_Event &event) {
+    switch (event.type) {
+    case SDL_EVENT_KEY_DOWN: {
+        if (event.key.key == SDLK_UP) {
+            if (m_LastAdvancedDirection == DIRECTION_RIGHT ||
+                m_LastAdvancedDirection == DIRECTION_LEFT)
+            {
+                m_Direction = DIRECTION_UP;
+            }
+        }
+        else if (event.key.key == SDLK_DOWN) {
+            if (m_LastAdvancedDirection == DIRECTION_RIGHT ||
+                m_LastAdvancedDirection == DIRECTION_LEFT)
+            {
+                m_Direction = DIRECTION_DOWN;
+            }
+        }
+        else if (event.key.key == SDLK_RIGHT) {
+            if (m_LastAdvancedDirection == DIRECTION_UP ||
+                m_LastAdvancedDirection == DIRECTION_DOWN)
+            {
+                m_Direction = DIRECTION_RIGHT;
+            }
+        }
+        else if (event.key.key == SDLK_LEFT) {
+            if (m_LastAdvancedDirection == DIRECTION_UP ||
+                m_LastAdvancedDirection == DIRECTION_DOWN)
+            {
+                m_Direction = DIRECTION_LEFT;
+            }
+        }
+        else if (event.key.key == SDLK_ESCAPE) {
+            m_IsPaused = true;
+        }
+    }
+
+    default:;
+    }
+}
+
+void Snake::SpawnFood() {
+    int32_t bit0_counts[MAX_MAP_HEIGHT];
+    int32_t bit0_count_total = 0;
+
+    // count bits
+    for (int32_t y = 0; y < m_MapHeight; y++) {
+        int32_t bit1_count = 0;
+
+        uint64_t bitmap_row = m_BodyBitmap[y];
+        while (bitmap_row != 0) {
+            bitmap_row = bitmap_row & (bitmap_row - 1);
+            bit1_count += 1;
+        }
+
+        int32_t bit0_count = m_MapWidth - bit1_count;
+        bit0_counts[y] = bit0_count;
+        bit0_count_total += bit0_count;
+    }
+
+    if (bit0_count_total == 0) {
+        return;
+    }
+
+    m_Dist.param(std::uniform_int_distribution<int32_t>::param_type(0, bit0_count_total - 1));
+    int32_t bit0_index = m_Dist(m_Rng);
+    int32_t bit0_x = 0;
+    int32_t bit0_y = 0;
+
+    // find y
+    for (int32_t y = 0; y < m_MapHeight; y++) {
+        if (bit0_index < bit0_counts[y]) {
+            bit0_y = y;
+            break;
+        }
+        bit0_index -= bit0_counts[y];
+    }
+
+    // find x
+    uint64_t bitmap_row_not = ~m_BodyBitmap[bit0_y];
+    for (int32_t x = 0; x < m_MapWidth; x++) {
+        if (bitmap_row_not & 1) {
+            if (bit0_index == 0) {
+                bit0_x = x;
+                break;
+            }
+            bit0_index--;
+        }
+        bitmap_row_not >>= 1;
+    }
+
+    m_FoodPosition = {bit0_x, bit0_y};
+}
+
+void Snake::Draw(RenderGroup &render_group) {
+    float world_width = 4.0f;
+    float world_height = 3.0f;
+
+    float tile_size = (world_width / 2) / MAX_MAP_WIDTH;
+    float bodypart_size = 0.8f * tile_size;
+    float bodypart_offset = (tile_size - bodypart_size) / 2;
+
+    float map_view_width = tile_size * (float)m_MapWidth;
+    float map_view_height = tile_size * (float)m_MapHeight;
+    float map_x = (world_width - map_view_width) / 2;
+    float map_y = (world_height - map_view_height) / 2;
+
+    int32_t max_positions = sizeof(m_BodyPositions) / sizeof(m_BodyPositions[0]);
+
+
+    /* draw map background */
+    V3F32 map_world_pos = {map_x, map_y, 0.0f};
+    V2F32 map_world_dim = {map_view_width, map_view_height};
+    V3F32 bg_color = {0.0f, 0.0f, 0.0f};
+    render_group.PushRectangle(map_world_pos, map_world_dim, bg_color);
+
+
+    /* draw snake */
+    // 1) if tail > head: advance to end first
+    int32_t tail = m_Tail;
+    if (tail > m_Head) {
+        while (tail < max_positions) {
+            V3F32 local_pos = {
+                (float)m_BodyPositions[tail].x * tile_size + bodypart_offset,
+                (float)m_BodyPositions[tail].y * tile_size + bodypart_offset,
+                1.0f
+            };
+            V2F32 local_dim = {bodypart_size, bodypart_size};
+
+            V3F32 world_pos = {
+                map_world_pos.x + local_pos.x,
+                map_world_pos.y + local_pos.y,
+                1.0f
+            };
+            V2F32 world_dim = local_dim;
+
+            V3F32 color = {0.3f, 0.3f, 0.3f};
+            render_group.PushRectangle(world_pos, world_dim, color);
+            tail++;
+        }
+        tail = 0;
+    }
+    // 2) advance to head
+    while (tail <= m_Head) {
+        V3F32 local_pos = {
+            (float)m_BodyPositions[tail].x * tile_size + bodypart_offset,
+            (float)m_BodyPositions[tail].y * tile_size + bodypart_offset,
+            1.0f
+        };
+        V2F32 local_dim = {bodypart_size, bodypart_size};
+
+        V3F32 world_pos = {
+            map_world_pos.x + local_pos.x,
+            map_world_pos.y + local_pos.y,
+            1.0f
+        };
+        V2F32 world_dim = local_dim;
+
+        V3F32 color = {0.3f, 0.3f, 0.3f};
+        render_group.PushRectangle(world_pos, world_dim, color);
+        tail++;
+    }
+
+
+    /* draw food */
+    V3F32 pos = {
+        map_world_pos.x + (float)m_FoodPosition.x * tile_size + bodypart_offset,
+        map_world_pos.y + (float)m_FoodPosition.y * tile_size + bodypart_offset,
+        1.0f
+    };
+    V2F32 dim = {bodypart_size, bodypart_size};
+    V3F32 color = {0.3f, 0.6f, 0.4f};
+    render_group.PushRectangle(pos, dim, color);
+}
+
+void Snake::DoImgui() {
+    if (m_IsPaused) {
+        ImGui::Begin("SnakePause");
+        if (ImGui::Button("Resume")) {
+            m_IsPaused = false;
+        }
+        if (ImGui::Button("Exit")) {
+            m_IsRunning = false;
+        }
+        ImGui::End();
+    }
+}
+
diff --git a/src/games/snake/Snake.hpp b/src/games/snake/Snake.hpp
new file mode 100644
index 0000000..f04ad16
--- /dev/null
+++ b/src/games/snake/Snake.hpp
@@ -0,0 +1,62 @@
+#pragma once
+
+#include <renderer/RenderGroup.hpp>
+#include <games/Game.hpp>
+
+#include <random>
+
+
+class Snake : public Game {
+public:
+    enum Direction : int32_t {
+        DIRECTION_UP,
+        DIRECTION_DOWN,
+        DIRECTION_LEFT,
+        DIRECTION_RIGHT,
+    };
+
+
+public:
+    Snake();
+    bool Update(std::vector<SDL_Event> &events, RenderGroup &render_group) override;
+
+
+private:
+    void ProcessEventDuringPause(SDL_Event &event);
+    void ProcessEventDuringResume(SDL_Event &event);
+
+    void MaybeMoveSnake(float dt_in_seconds);
+    void SpawnFood();
+
+    void Draw(RenderGroup &render_group);
+    void DoImgui();
+
+
+
+private:
+    static constexpr int32_t MAX_MAP_WIDTH = 16;
+    static constexpr int32_t MAX_MAP_HEIGHT = 16;
+
+    bool m_IsPaused;
+    bool m_IsRunning;
+
+    float m_DtInSecondsRemaining;
+    uint64_t m_LastMillisecondsSinceT0;
+
+    float m_TilesPerSecond;
+    Direction m_Direction;
+    Direction m_LastAdvancedDirection;
+
+    int32_t m_MapWidth;
+    int32_t m_MapHeight;
+    int32_t m_Tail;
+    int32_t m_Head;
+    uint64_t m_BodyBitmap[MAX_MAP_HEIGHT];
+    V2I32 m_BodyPositions[MAX_MAP_WIDTH * MAX_MAP_HEIGHT];
+    V2I32 m_FoodPosition;
+
+    std::mt19937 m_Rng;
+    std::uniform_int_distribution<int32_t> m_Dist;
+};
+
+