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

#include <math.h>
#include <stdio.h>
#include <stdlib.h>

#include "game.h"
#include "const.h"
#include "movement.h"
#include "spawn.h"

#include "system/mouse_io.h"
#include "system/pc_stuff.h"

void captureAndLimitMousePosition(
  struct RabbitPosition *pos,
  struct MouseStatus *mouseStatus
) {
  pos->oldMouseDotPosition[0] = pos->mouseDotPosition[0];
  pos->oldMouseDotPosition[1] = pos->mouseDotPosition[1];

  pos->mouseDotPosition[0] = mouseStatus->xPosition;
  pos->mouseDotPosition[1] = mouseStatus->yPosition;

  if (pos->mouseDotPosition[0] < MOUSE_LIMIT_LEFT) pos->mouseDotPosition[0] = MOUSE_LIMIT_LEFT;
  if (pos->mouseDotPosition[0] >= MOUSE_LIMIT_RIGHT) pos->mouseDotPosition[0] = MOUSE_LIMIT_RIGHT;
  if (pos->mouseDotPosition[1] < MOUSE_LIMIT_TOP) pos->mouseDotPosition[1] = MOUSE_LIMIT_TOP;
  if (pos->mouseDotPosition[1] >= MOUSE_LIMIT_BOTTOM) pos->mouseDotPosition[1] = MOUSE_LIMIT_BOTTOM;
}

void calculateTargetAngle(
  struct RabbitPosition *pos
) {
  int targetX, targetY;
  float distanceX, distanceY;
  float angle, fixHypotenuse, fixDistance;

  // Position the cursor
  distanceX = pos->mouseDotPosition[0] - pos->rabbitPosition[0];
  distanceY = pos->mouseDotPosition[1] - pos->rabbitPosition[1];

  angle = atan2(distanceY, distanceX) * RAD2DEG + 90;
  if (angle < 0) angle += 360;

  distanceX = sin(angle * DEG2RAD) * MOUSE_DISTANCE;
  distanceY = -cos(angle * DEG2RAD) * MOUSE_DISTANCE;

  pos->oldMousePosition[0] = pos->mousePosition[0];
  pos->oldMousePosition[1] = pos->mousePosition[1];

  targetX = pos->rabbitPosition[0] + distanceX;
  targetY = pos->rabbitPosition[1] + distanceY;

  if (targetX > (ARENA_WIDTH_TILES - 1) * TILE_SIZE) {
    fixDistance = targetX - ((ARENA_WIDTH_TILES - 1) * TILE_SIZE);
    fixHypotenuse = fixDistance / sin(angle * DEG2RAD);
    targetX = (ARENA_WIDTH_TILES - 1) * TILE_SIZE;
    targetY = pos->rabbitPosition[1] + -cos(angle * DEG2RAD) * -fixHypotenuse;
  }

  pos->mousePosition[0] = targetX;
  pos->mousePosition[1] = targetY;

  pos->mouseAngle = angle;
}

#define SIGN(x) ((x > 0) - (x < 0))

void handleEnemyMovement(
  struct EnemyPosition enemyPosition[],
  struct RabbitPosition *pos
) {
  char hasExitedGate;
  int i, xDistance, yDistance;

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

    enemyPosition[i].enemyMoveDelayStep += 1;
    if (enemyPosition[i].enemyMoveDelayStep < ENEMY_MOVE_DELAY) continue;
    enemyPosition[i].enemyMoveDelayStep = 0;

    enemyPosition[i].oldEnemyPosition[0] = enemyPosition[i].enemyPosition[0];
    enemyPosition[i].oldEnemyPosition[1] = enemyPosition[i].enemyPosition[1];

    if (enemyPosition[i].hasLeftGate) {
      // which straight directon is the player closest to
      xDistance = pos->rabbitPosition[0] - enemyPosition[i].enemyPosition[0];
      yDistance = pos->rabbitPosition[1] - enemyPosition[i].enemyPosition[1];

      if (abs(xDistance) > abs(yDistance)) {
        enemyPosition[i].enemyPosition[0] += SIGN(xDistance) * ENEMY_MOVE_SPEED;
      } else {
        enemyPosition[i].enemyPosition[1] += SIGN(yDistance) * ENEMY_MOVE_SPEED;
      }
    } else {
      switch (enemyPosition[i].gateExitedFrom) {
        // top
        case 0:
          xDistance = 0;
          yDistance = ENEMY_MOVE_SPEED;
          break;
        // right
        case 1:
          xDistance = -ENEMY_MOVE_SPEED;
          yDistance = 0;
          break;
        // bottom
        case 2:
          xDistance = 0;
          yDistance = -ENEMY_MOVE_SPEED;
          break;
        // left
        case 3:
          xDistance = ENEMY_MOVE_SPEED;
          yDistance = 0;
          break;
      }

      enemyPosition[i].enemyPosition[0] += xDistance;
      enemyPosition[i].enemyPosition[1] += yDistance;

      switch (enemyPosition[i].gateExitedFrom) {
        case 0:
          hasExitedGate = (
            enemyPosition[i].enemyPosition[1] > spawnPointRanges[0].top + spawnPointRanges[0].height
          );
          break;
        case 1:
          hasExitedGate = (
            enemyPosition[i].enemyPosition[0] < spawnPointRanges[1].left
          );
          break;
        case 2:
          hasExitedGate = (
            enemyPosition[i].enemyPosition[1] < spawnPointRanges[2].top
          );
          break;
        case 3:
          hasExitedGate = (
            enemyPosition[i].enemyPosition[0] > spawnPointRanges[3].left + spawnPointRanges[3].width
          );
          break;
      }

      enemyPosition[i].hasLeftGate = hasExitedGate;
    }
  }
}

void handleRabbitMovement(
  struct RabbitPosition *pos,
  struct KeyboardKeydownState *keyboardKeydownState
) {
  int i;

  if (keyboardKeydownState->KEY_W) {
    pos->rabbitVelocity[1] -= RABBIT_MOTION_ACCELERATION;
    if (pos->rabbitVelocity[1] < -RABBIT_MOTION_MAX_SPEED) {
      pos->rabbitVelocity[1] = -RABBIT_MOTION_MAX_SPEED;
    }
  }
  if (keyboardKeydownState->KEY_S) {
    pos->rabbitVelocity[1] += RABBIT_MOTION_ACCELERATION;
    if (pos->rabbitVelocity[1] > RABBIT_MOTION_MAX_SPEED) {
      pos->rabbitVelocity[1] = RABBIT_MOTION_MAX_SPEED;
    }
  }
  if (keyboardKeydownState->KEY_A) {
    pos->rabbitVelocity[0] -= RABBIT_MOTION_ACCELERATION;
    if (pos->rabbitVelocity[0] < -RABBIT_MOTION_MAX_SPEED) {
      pos->rabbitVelocity[0] = -RABBIT_MOTION_MAX_SPEED;
    }
  }
  if (keyboardKeydownState->KEY_D) {
    pos->rabbitVelocity[0] += RABBIT_MOTION_ACCELERATION;
    if (pos->rabbitVelocity[0] > RABBIT_MOTION_MAX_SPEED) {
      pos->rabbitVelocity[0] = RABBIT_MOTION_MAX_SPEED;
    }
  }

  for (i = 0; i < 2; ++i) {
    pos->oldRabbitPosition[i] = pos->rabbitPosition[i];
    pos->rabbitPosition[i] += (pos->rabbitVelocity[i] / RABBIT_MOTION_VELOCITY_DECAY);

    if (pos->rabbitPosition[i] < pos->rabbitLimits[0][i]) {
      pos->rabbitPosition[i] = pos->rabbitLimits[0][i];
    }
    if (pos->rabbitPosition[i] >= pos->rabbitLimits[1][i]) {
      pos->rabbitPosition[i] = pos->rabbitLimits[1][i];
    }

    if (pos->rabbitVelocity[i] < 0) {
      pos->rabbitVelocity[i] += RABBIT_MOTION_DRAG;
      if (pos->rabbitVelocity[i] > 0) pos->rabbitVelocity[i] = 0;
    }
    if (pos->rabbitVelocity[i] > 0) {
      pos->rabbitVelocity[i] -= RABBIT_MOTION_DRAG;
      if (pos->rabbitVelocity[i] < 0) pos->rabbitVelocity[i] = 0;
    }
  }
}