Looking for ideas about the player's shot in Defender...

[PacManPlus]

So, in keeping with the spirit of Defender, when I get back to work on it, I'm looking for ideas on how to do the player's shot on the screen.

 

The player's shot spans most of the horizontal area of the screen... which can be an issue when including the player, the player's thrust, and enemies, shots, etc. in the same zone. Plus, the shot begins / ends in an odd way (don't know any other way of explaining it).

I'm trying to think of any 'tricks' that would help here...

 

The player's explosion I'm going to change; to get more 'explosion particles' on the screen, I'm going to remove all enemies, and quickly switch to another DLL using a bunch of single-byte bitmaps. The enemy explosion will unfortunately have to be an in-place explosion instead of a particle one. There's just not enough Maria time... especially if you are killing multiple enemies in quick succession.

 

It would be cool if someone had disassembled Defender II for the 2600 or Defender for the 5200 with comments so I can see how some of the enemy AI was done... Or even the arcade version. That would get the game done much faster.

 

I tried contacting Eugene Jarvis, but unfortunately he was one of the few who never answered me. (I was lucky with Owen Rubin and Alan McNeil).

 

Anyway, hoping for some ideas for when I pick this up again.

Thanks,

Bob

[RevEng]

Trying to think a bit out of the box here...

 

Looking at a few youtube videos, I think you could get away with characters for the shots. They move a lot in each frame, so whole character animation of the shots would still look smooth.

 

If you allow 4 vertical "shots" per character cell (maybe forcing the craft to an even pixel position when stationary) you can cover any combination of shots with 16x different character graphics. If you want the shots to cross the landscape nicely, then you'd need 16 variations on each angular land tile. If you're clever with the graphics ROM layout, you can make it so the calculation for changing a tile to add a given Y-located shot is just an ORA operation on the existing tile index.

 

Defender arcade also has a sort of spackle texture on the shots. The spackled texture on the shot ends would add more character graphics to your requirements, and more charcter index updating per frame, but I don't think the shooting spackle would be missed if omitted.

 

Alternatively you could go with an all-RAM display and xor all of the player, enemies, and shots onto the bitmap. That's quite a bit more complicated, but it would get everything onto the screen. Colors may suffer, depending on the graphics mode used.

[PacManPlus]

The only problem I see using character modes for shots, is that I'm using character mode for the mountains, and the star background.

…maybe it is time to start over when I come back to that game...

[RevEng]

Yeah, the mountains was what I was referring to with "the landscape". Doable, if you have enough characters left in your set. Depending on the character mode you're using, you'll need one color index for the laser, and one for the landscape. If not, the color will be off at the intersection of laser and landscape.

 

I don't think the impact on the star background will be that obvious, but you could create 16 combined star+laser character graphics too.

[+SmittyB]

If you did use characters I don't think anyone would mind a bit of clashing, a lot of good C64 shooters used the tiled backgrounds to fake a huge number of shots on screen and nobody cared as long as the gameplay was good.

 

 

I've made a quick mockup (borrowing the C64 graphics for everything but the laser) of how I always thought I'd achieve a similar effect. There are several laser objects, eight at its peak length, with each subsequent one starting on a different frame of animation of the laser shrinking. You get subtly different effects depending on which side the laser shrinks from. Adding a colour-cycle effect just adds to it.

You could adjust how many objects make up the laser and the size / frames of the animation to make it fit what you need.

 

For some reason my editor saves GIF animations slower than they should be, but it looks better at full speed.

 

[RevEng]

Wow, that looks great!

[EricBall]

There's also no reason you can't have two layers of tiles (indirect sprites) onscreen at once. However, it does severely limit the number of sprites can have in the same zone. Or you can just use a very wide normal (direct) sprite.

[gambler172]

Hi Bob

 

do you know the XL version??

The shots look great at this.

But you know,i am a lousy programner.

 

[NostAlgae37]

So, in keeping with the spirit of Defender, when I get back to work on it...

 

Anyway, hoping for some ideas for when I pick this up again.

Thanks,

Bob

 

[PacManPlus]

That looks good and may work... I just need to figure out what to do with the terrain, and the stars. I can't put another layer of tiles, because more often than not there will be other enemies, maybe a few of their shots, etc... I'll see.

Thanks guys