dos-vga-arena-shooter-game/game.c

#include <stddef.h>
#include <stdio.h>
#include <math.h>
#include <conio.h>
#include <stdlib.h>
#include <time.h>

#include "sprites.h"
#include "system/vga.h"
#include "system/keyboard.h"
#include "system/mouse_io.h"
#include "system/pc_stuff.h"

#include "bmpload.h"
#include "const.h"
#include "arena.h"
#include "movement.h"
#include "combat.h"
#include "game.h"

// TODO: centralize these outside of game.c
struct CompiledSpriteRender rabbit,
  mouse,
  bullet,
  enemy,
  enemyBullet,
  shotgun,
  shieldKiller;
struct SpriteBounds bounds;

struct BMPImage spritesheetImage;
struct VGAColor vgaColors[256];

struct MouseStatus mouseStatus;

struct RabbitPosition rabbitPosition = {
  .rabbitPosition = { 60, 60 },
  .rabbitLimits = {
    { 20, 20 },
    { (ARENA_WIDTH_TILES - 1) * TILE_SIZE - 2, (ARENA_HEIGHT_TILES - 1) * TILE_SIZE - 2 }
  },
  .mousePosition = { 0, 0 },
  .rabbitVelocity = { 0, 0 },
  .mouseDotPosition = { 0, 0 }
};
struct EnemyPosition enemyPosition[ENEMY_MAX_COUNT];
struct BulletPosition rabbitBulletPosition[RABBIT_BULLET_LIMIT];
struct BulletPosition enemyBulletPosition[ENEMY_BULLET_LIMIT];
struct RabbitWeaponry rabbitWeaponry;
struct PlayerPowerup playerPowerup;

struct SpawnPointRange spawnPointRanges[4] = {
   // top
   { .left = TILE_SIZE * 4, .width = TILE_SIZE * 2, .top = TILE_SIZE - 8, .height = TILE_SIZE },
   // right
   { .left = (ARENA_WIDTH_TILES - 1) * TILE_SIZE - 8, .width = TILE_SIZE, .top = TILE_SIZE * 4, .height = TILE_SIZE * 2 },
   // bottom
   { .left = TILE_SIZE * 4, .width = TILE_SIZE * 2, .top = (ARENA_HEIGHT_TILES - 1) * TILE_SIZE - 8, .height = TILE_SIZE },
   // left
   { .left = TILE_SIZE - 8, .width = TILE_SIZE, .top = TILE_SIZE * 4, .height = TILE_SIZE * 2 },
};

void setupRabbitBullets() {
  int i;

  for (i = 0; i < RABBIT_BULLET_LIMIT; ++i) {
    rabbitBulletPosition[i].isActive = 0;
    rabbitBulletPosition[i].willBeInactive = 0;
  }

  rabbitWeaponry.cooldown = 0;
  rabbitWeaponry.currentWeapon = WEAPON_TYPE_SINGLE_SHOT_GUN;
  rabbitWeaponry.currentWeaponRemainingRounds = 0;
}

void setupPowerup() {
  playerPowerup.x = 100;
  playerPowerup.y = 100;
  playerPowerup.cooldown = 20 + rand() % 10;
  playerPowerup.type = POWERUP_TYPE_SHOTGUN;
  playerPowerup.isActive = 0;
}

void setupEnemyBullets() {
  int i;

  for (i = 0; i < ENEMY_BULLET_LIMIT; ++i) {
    enemyBulletPosition[i].isActive = 0;
    enemyBulletPosition[i].willBeInactive = 0;
  }
}

void setupEnemies() {
  int i;

  for (i = 0; i < ENEMY_MAX_COUNT; ++i) {
    enemyPosition[i].isActive = 0;
    enemyPosition[i].willBeInactive = 0;
  }
}

int spawnCooldown = 0;
int difficulty = 0;
int kills = 0;
int health = RABBIT_HEALTH_MAX;

int difficultyBands[10] = { 10, 20, 30, 50, 80, 130, 210, 340, 550, 890 };

void handleEnemyKills() {
  int i, hadKill, currentKillCount;

  currentKillCount = 0;

  for (i = 0; i < ENEMY_MAX_COUNT; ++i) {
    if (enemyPosition[i].wasKilled) {
      enemyPosition[i].wasKilled = 0;
      kills++;
      currentKillCount++;
      health += ENEMY_KILL_HEALTH_GAIN;
      if (health > RABBIT_HEALTH_MAX) health = RABBIT_HEALTH_MAX;

      hadKill = 1;
    }
  }

  kills += currentKillCount;

  playerPowerup.cooldown -= currentKillCount;
  if (playerPowerup.cooldown <= 0) {
    playerPowerup.x = TILE_SIZE + rand() % ((ARENA_WIDTH_TILES - 2) * TILE_SIZE);
    playerPowerup.y = TILE_SIZE + rand() % ((ARENA_HEIGHT_TILES - 2) * TILE_SIZE);
    playerPowerup.isActive = 1;

    playerPowerup.cooldown = POWERUP_RESPAWN_COOLDOWN_PER_LEVEL * difficulty +
      rand() % (POWERUP_RESPAWN_COOLDOWN_PER_LEVEL * difficulty);
  }

  if (hadKill) {
    for (i = 0; i < 10; ++i) {
      if (kills > difficultyBands[i]) {
        difficulty = i + 1;
      }
    }
  }
}

void maybeSpawnEnemy() {
  char canSpawn;
  int i, gate, availableEnemy, gatePlayerIsFacing;
  int spawnX, spawnY, spawnTry;

  char buffer[20];

  if (spawnCooldown-- > 0) return;

  for (i = 0; i < ENEMY_MAX_COUNT; ++i) {
    if (!enemyPosition[i].isActive) {
      availableEnemy = i;
      canSpawn = 1;
      break;
    }
  }

  if (!canSpawn) return;

  // determine which gate the player is at and reduce the likelihood of
  // spawning from that gate
  // * 8 chances to spawn [0, 1] for each gate
  // * if the gate the player is looking at gets [0], reroll
  // * try three times max to limit cost of calculating
  for (spawnTry = 0; spawnTry < 3; ++spawnTry) {
    i = rand() % 12;
    gate = i / 3;

    if (gatePlayerIsFacing == gate && i % 3 != 0) continue;
  }

  spawnX = spawnPointRanges[gate].left + rand() % spawnPointRanges[gate].width;
  spawnY = spawnPointRanges[gate].top + rand() % spawnPointRanges[gate].height;

  enemyPosition[availableEnemy].isActive = 1;
  enemyPosition[availableEnemy].willBeInactive = 0;
  enemyPosition[availableEnemy].wasKilled = 0;
  enemyPosition[availableEnemy].hitPoints = 1 + difficulty / ENEMY_HIT_POINT_DIFFICULTY_INCREASE_EVERY;
  enemyPosition[availableEnemy].hasLeftGate = 0;
  enemyPosition[availableEnemy].gateExitedFrom = gate;
  enemyPosition[availableEnemy].enemyMoveDelayStep = 0;
  enemyPosition[availableEnemy].enemyFireDelayStep = ENEMY_FIRE_MIN_DELAY + rand() % ENEMY_FIRE_VARIABLE_DELAY;
  enemyPosition[availableEnemy].enemyPosition[0] = spawnX;
  enemyPosition[availableEnemy].enemyPosition[1] = spawnY;
  enemyPosition[availableEnemy].oldEnemyPosition[0] = spawnX;
  enemyPosition[availableEnemy].oldEnemyPosition[1] = spawnY;

  spawnCooldown = (BASE_ENEMY_SPAWN_COOLDOWN - (difficulty * DIFFICULTY_SPAWN_COOLDOWN_REDUCTION)) + MINIMUM_ENEMY_SPAWN_COOLDOWN + rand() % VARIABLE_ENEMY_SPAWN_COOLDOWN;
}

void setupEnemySprites() {
  buildCompiledSprite(
    &sprite_enemy,
    &enemy,
    SPRITE_ENEMY_WIDTH,
    SPRITE_ENEMY_HEIGHT,
    SPRITE_ENEMY_OFFSET_X,
    SPRITE_ENEMY_OFFSET_Y
  );

  buildCompiledSprite(
    &sprite_bullet,
    &enemyBullet,
    SPRITE_BULLET_WIDTH,
    SPRITE_BULLET_HEIGHT,
    SPRITE_BULLET_OFFSET_X,
    SPRITE_BULLET_OFFSET_Y
  );
}

void setupRabbitSprites() {
  buildCompiledSprite(
    &sprite_rabbit,
    &rabbit,
    SPRITE_RABBIT_WIDTH,
    SPRITE_RABBIT_HEIGHT,
    SPRITE_RABBIT_OFFSET_X,
    SPRITE_RABBIT_OFFSET_Y
  );

  buildCompiledSprite(
    &sprite_mouse,
    &mouse,
    SPRITE_MOUSE_WIDTH,
    SPRITE_MOUSE_HEIGHT,
    SPRITE_MOUSE_OFFSET_X,
    SPRITE_MOUSE_OFFSET_Y
  );

  buildCompiledSprite(
    &sprite_bullet,
    &bullet,
    SPRITE_BULLET_WIDTH,
    SPRITE_BULLET_HEIGHT,
    SPRITE_BULLET_OFFSET_X,
    SPRITE_BULLET_OFFSET_Y
  );
}

void setupPowerupSprites() {
  buildCompiledSprite(
    &sprite_shotgun,
    &shotgun,
    SPRITE_SHOTGUN_WIDTH,
    SPRITE_SHOTGUN_HEIGHT,
    SPRITE_SHOTGUN_OFFSET_X,
    SPRITE_SHOTGUN_OFFSET_Y
  );

  buildCompiledSprite(
    &sprite_shieldKiller,
    &shieldKiller,
    SPRITE_SHIELDKILLER_WIDTH,
    SPRITE_SHIELDKILLER_HEIGHT,
    SPRITE_SHIELDKILLER_OFFSET_X,
    SPRITE_SHIELDKILLER_OFFSET_Y
  );
}

void renderMouse() {
  mouse.x = rabbitPosition.mousePosition[0];
  mouse.y = rabbitPosition.mousePosition[1];
  drawCompiledSprite(&mouse);
  drawPixel(rabbitPosition.mouseDotPosition[0], rabbitPosition.mouseDotPosition[1], 2);
}

void renderRabbit() {
  rabbit.x = rabbitPosition.rabbitPosition[0];
  rabbit.y = rabbitPosition.rabbitPosition[1];
  drawCompiledSprite(&rabbit);
}

void renderEnemies() {
  int i;

  for (i = 0; i < ENEMY_MAX_COUNT; ++i) {
    if (!enemyPosition[i].isActive) continue;

    enemy.x = enemyPosition[i].enemyPosition[0];
    enemy.y = enemyPosition[i].enemyPosition[1];
    drawCompiledSprite(&enemy);
  }
}

void renderRabbitBullets() {
  char i;

  for (i = 0; i < RABBIT_BULLET_LIMIT; ++i) {
    if (!rabbitBulletPosition[i].isActive) continue;

    bullet.x = rabbitBulletPosition[i].x;
    bullet.y = rabbitBulletPosition[i].y;
    drawCompiledSprite(&bullet);
  }
}

void renderEnemyBullets() {
  char i;

  for (i = 0; i < ENEMY_BULLET_LIMIT; ++i) {
    if (!enemyBulletPosition[i].isActive) continue;

    enemyBullet.x = enemyBulletPosition[i].x;
    enemyBullet.y = enemyBulletPosition[i].y;
    drawCompiledSprite(&enemyBullet);
  }
}

void renderPowerup() {
  if (!playerPowerup.isActive) return;

  switch (playerPowerup.type) {
    case POWERUP_TYPE_SHOTGUN:
      shotgun.x = playerPowerup.x;
      shotgun.y = playerPowerup.y;
      drawCompiledSprite(&shotgun);
      break;
    case POWERUP_TYPE_SHIELD_KILLER:
      shieldKiller.x = playerPowerup.x;
      shieldKiller.y = playerPowerup.y;
      drawCompiledSprite(&shieldKiller);
      break;
  }
}

void drawOnlyArenaForSprite(struct CompiledSpriteRender *sprite) {
  getSpriteBounds(sprite, &bounds);
  drawOnlyArena(&bounds);
}

void drawOnlyMouseArena() {
  mouse.x = rabbitPosition.oldMousePosition[0];
  mouse.y = rabbitPosition.oldMousePosition[1];
  drawOnlyArenaForSprite(&mouse);

  bounds.top = rabbitPosition.oldMouseDotPosition[1];
  bounds.bottom = rabbitPosition.oldMouseDotPosition[1];
  bounds.left = rabbitPosition.oldMouseDotPosition[0];
  bounds.right = rabbitPosition.oldMouseDotPosition[0];
  drawOnlyArena(&bounds);
}

void drawOnlyRabbitArena() {
  rabbit.x = rabbitPosition.oldRabbitPosition[0];
  rabbit.y = rabbitPosition.oldRabbitPosition[1];
  drawOnlyArenaForSprite(&rabbit);
}

void drawOnlyPowerupArena() {
  if (!playerPowerup.isActive) return;

  switch (playerPowerup.type) {
    case POWERUP_TYPE_SHOTGUN:
      shotgun.x = playerPowerup.x;
      shotgun.y = playerPowerup.y;
      drawOnlyArenaForSprite(&shotgun);
      break;
    case POWERUP_TYPE_SHIELD_KILLER:
      shieldKiller.x = playerPowerup.x;
      shieldKiller.y = playerPowerup.y;
      drawOnlyArenaForSprite(&shieldKiller);
      break;
  }

  if (playerPowerup.willBeInactive) {
    playerPowerup.isActive = 0;
  }
}

void drawOnlyEnemiesArena() {
  int i;

  for (i = 0; i < ENEMY_MAX_COUNT; ++i) {
    if (!enemyPosition[i].isActive) continue;

    enemy.x = enemyPosition[i].oldEnemyPosition[0];
    enemy.y = enemyPosition[i].oldEnemyPosition[1];
    drawOnlyArenaForSprite(&enemy);

    if (enemyPosition[i].willBeInactive) {
      enemyPosition[i].isActive = 0;
    }
  }
}

void drawOnlyRabbitBulletArena() {
  int i;
  for (i = 0; i < RABBIT_BULLET_LIMIT; ++i) {
    if (!rabbitBulletPosition[i].isActive) continue;

    bullet.x = rabbitBulletPosition[i].oldX;
    bullet.y = rabbitBulletPosition[i].oldY;
    drawOnlyArenaForSprite(&bullet);

    if (rabbitBulletPosition[i].willBeInactive) {
      rabbitBulletPosition[i].isActive = 0;
    }
  }
}

void drawOnlyEnemyBulletArena() {
  int i;
  for (i = 0; i < ENEMY_BULLET_LIMIT; ++i) {
    if (!enemyBulletPosition[i].isActive) continue;

    enemyBullet.x = enemyBulletPosition[i].oldX;
    enemyBullet.y = enemyBulletPosition[i].oldY;
    drawOnlyArenaForSprite(&enemyBullet);

    if (enemyBulletPosition[i].willBeInactive) {
      enemyBulletPosition[i].isActive = 0;
    }
  }
}

int setupGame() {
  FILE *fh;

  installKeyboardHandler();
  initializeDrawBuffer();

  fh = fopen("sprtsht.bmp", "rb");
  if (readBMPIntoNewMemory(fh, &spritesheetImage)) return 1;
  fclose(fh);

  spritesheetImage.transparentColor = 0;

  setupWallSprites();
  setupRabbitSprites();
  setupRabbitBullets();
  setupEnemies();
  setupEnemyBullets();
  setupEnemySprites();
  setupPowerup();
  setupPowerupSprites();

  setVideoMode(VIDEO_MODE_VGA_256);
  bmp256ColorPaletteToVGAColorPalette(&spritesheetImage, vgaColors);
  setVGAColors(vgaColors, 256);

  activateMouse(&mouseStatus);

  buildArena();
  clearArenaRedrawRequests();

  srand(time(NULL));

  return 0;
}

void handleMovement() {
  handleRabbitMovement(
    &rabbitPosition,
    &keyboardKeydownState
  );
  handleEnemyMovement(
    enemyPosition,
    &rabbitPosition
  );
  captureAndLimitMousePosition(
    &rabbitPosition,
    &mouseStatus
  );
  calculateTargetAngle(
    &rabbitPosition,
    &mouseStatus
  );
}

void handleCombat() {
  int didHitRabbit;

  if (mouseStatus.leftButtonDown) {
    if (attemptToFireRabbitBullet(
      &rabbitPosition,
      &rabbitWeaponry,
      rabbitBulletPosition
    )) {
      if (rabbitWeaponry.currentWeaponRemainingRounds > 0) {
        rabbitWeaponry.currentWeaponRemainingRounds--;
        if (rabbitWeaponry.currentWeaponRemainingRounds == 0) {
          rabbitWeaponry.currentWeapon = WEAPON_TYPE_SINGLE_SHOT_GUN;
        }
      }
    }
  }

  attemptToFireEnemyBullets(
    enemyPosition,
    enemyBulletPosition,
    &rabbitPosition,
    difficulty
  );

  advanceRabbitBullets(
    rabbitBulletPosition,
    &rabbitWeaponry
  );

  advanceEnemyBullets(
    enemyBulletPosition
  );

  buildCollisionGrids(
    rabbitBulletPosition,
    enemyBulletPosition,
    &rabbitPosition,
    enemyPosition,
    &playerPowerup
  );

  didHitRabbit = handleRabbitToEnemyCollisions(
    &rabbitPosition,
    enemyPosition
  );

  if (didHitRabbit) {
    health -= ENEMY_COLLISION_DAMAGE * didHitRabbit;
  }

  didHitRabbit = handleEnemyBulletToRabbitCollisions(
    enemyBulletPosition,
    &rabbitPosition
  );

  if (didHitRabbit) {
    health -= ENEMY_BULLET_DAMAGE * didHitRabbit;
  }

  handleRabbitBulletToEnemyCollisions(
    rabbitBulletPosition,
    enemyPosition
  );

  if (handleRabbitToPowerupCollision(&rabbitPosition, &playerPowerup)) {
    playerPowerup.willBeInactive = 1;
    rabbitWeaponry.currentWeapon = WEAPON_TYPE_SPREAD_SHOT_GUN;
    rabbitWeaponry.currentWeaponRemainingRounds = (difficulty + 1) * SHOTGUN_ROUNDS_PER_LEVEL;
  }
}

void handleRedraw() {
  drawOnlyRabbitArena();
  drawOnlyEnemiesArena();
  drawOnlyMouseArena();
  drawOnlyRabbitBulletArena();
  drawOnlyEnemyBulletArena();
  drawOnlyPowerupArena();

  redrawArena();

  renderPowerup();
  renderRabbit();
  renderEnemies();
  renderMouse();
  renderRabbitBullets();
  renderEnemyBullets();
}

/*
double speedCalcs[200];
int currentSpeedCalc = 0;
double averageSpeedCalc;
clock_t startTime;
*/

int main(void) {
  byte *drawBuffer;
  int keepRunning = 1;
  int i;

  char buffer[20];

  if (setupGame()) return 1;

  drawBuffer = getDrawBuffer();

  while (keepRunning) {
    readMouse(&mouseStatus);
    populateKeyboardKeydownState();

    maybeSpawnEnemy();

    handleMovement();
    handleRedraw();
    handleCombat();
    handleEnemyKills();

    sprintf(buffer, "Hit: %d", kills);
    renderStringToDrawBuffer(buffer, 1, 0, 210, 20);
    sprintf(buffer, "Health: %d  ", health);
    renderStringToDrawBuffer(buffer, 1, 0, 210, 30);
    sprintf(buffer, "Rnds: %d  ", rabbitWeaponry.currentWeaponRemainingRounds);
    renderStringToDrawBuffer(buffer, 1, 0, 210, 40);

    waitStartVbl();
    copyDrawBufferToDisplay();

    waitEndVbl();

    if (keyboardKeydownState.KEY_ESC) { keepRunning = 0; }
  }

  freeBMP(&spritesheetImage);

  setVideoMode(VIDEO_MODE_80x25_TEXT);
  uninstallKeyboardHandler();

  /*
  averageSpeedCalc = 0;
  for (currentSpeedCalc = 0; currentSpeedCalc < 200; ++currentSpeedCalc) {
    averageSpeedCalc += speedCalcs[currentSpeedCalc];
  }

  averageSpeedCalc /= 200;

  fprintf(stderr, "average: %f\n", averageSpeedCalc);
  */

  return 0;
}