The BitBull Blog

The next enemy is the last from Defender I need to (loosely) implement. The Defender version is called the ‘baiter’, a small UFO that appears if you take too long to complete a level and gives you all kinds of grief. My version is similarly evil so I’m calling it simply ‘The Bastard’ – because it’s a bit of a bastard.

I thought I’d keep a ‘flying saucer’ aspect to the character design so we have a little alien dude piloting a UFO. It didn’t take me too long to get the basic design sorted but the animation was a bit of a pain. The little spinning antennae at the bottom of the UFO needed to animate at a different rate to the rotation of the UFO itself which meant I needed to split the enemy into two different sprites. Then I thought the pilot looked a bit static and I should try and animate him simply so it looked like he was flipping various controls to steer the craft – this looked rubbish on a loop so I split this out into yet another separate sprite and chose the animation frame randomly rather running on a sequence. It also animates a lot slower than the craft itself. Final touch was to add some particles for an ‘anti-gravity’ type effect.

I could base the motion heavily on the motion for the ‘mother‘ which is one of the reasons this enemy was fairly quick to implement. Every 10 frames the ‘bastard’ samples the player’s location and moves towards it. It’s much faster than the ‘mother‘ and the sampling rate is more frequent which makes it a lot more dangerous! To add a slightly more erratic feel I skip the sampling of the player’s location every three iterations or so.

This straightforward AI worked pretty well but I wasn’t happy with the way the enemy sometimes hovered over the player. I improved this by making the enemy ‘retreat’ when it collided with the player or fired a bullet. It alternates the retreat by flying to the top right, top left or directly above the player. This attack/retreat motion, whilst still pretty ‘dumb’, looked considerably more ‘intelligent’ than simply ramming the player the whole time.

The ‘bastard’ is pretty dangerous – maybe too dangerous. Now I’ve got a few different enemy types in place I think I’m going to have to start working on different weapons and the weapon upgrade system so I can see how these enemies play out against a more powerful opponent. The ‘pistol’ I’ve implemented so far is to be the most underpowered weapon in the game after all.

Dev Time: 1 day
Total Dev Time: approx 59.5 days

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