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I have been wondering exactly how I would implement 'proper' bouncy bullets (not the ping-pong cop-out currently in place) for some time. I thought I'd ask ChatGPT today and it sounds like it has devised a workable solution. I never thought when I started this project that at least one of its features would get devised by an AI! Amazing times.

My question to ChatGPT was:

How might I improve processBullets() so that the bullets will deflect off multiple surfaces and not just ping-pong between 2 walls?

It's reply:

To make the bullets deflect off multiple surfaces, you will need to update the processBullets() function to check for collisions with all walls in the level, not just the two adjacent walls.

One way to do this would be to use a 2D array to represent the level layout, with each element in the array representing a tile on the screen. You can then use the bullet's position and velocity to determine which tiles it will pass through during each frame. For each tile that the bullet will pass through, you can check if that tile is a wall or not, and if it is, you can calculate the new velocity for the bullet based on the angle of the wall and the direction the bullet was coming from.

Here is some pseudocode that demonstrates this approach:

void processBullets() {
  for each bullet {
    int startX = bullet.x / 8; // convert from pixels to tile units
    int startY = bullet.y / 8;
    int endX = (bullet.x + bullet.vX) / 8;
    int endY = (bullet.y + bullet.vY) / 8;

    // Check if the bullet is moving horizontally or vertically
    if (startX == endX) {
      // Bullet is moving vertically
      int direction = (bullet.vY > 0) ? 1 : -1;
      for (int y = startY; y != endY; y += direction) {
        if (level[y][startX] == WALL) {
          // Collision with vertical wall, reverse Y velocity
          bullet.vY = -bullet.vY;
          break;
        }
      }
    } else {
      // Bullet is moving horizontally
      int direction = (bullet.vX > 0) ? 1 : -1;
      for (int x = startX; x != endX; x += direction) {
        if (level[startY][x] == WALL) {
          // Collision with horizontal wall, reverse X velocity
          bullet.vX = -bullet.vX;
          break;
        }
      }
    }

    // Update bullet position based on new velocity
    bullet.x += bullet.vX;
    bullet.y += bullet.vY;
  }
}

This approach will allow the bullets to deflect off multiple walls and surfaces in the level.