Making a Will o' Wisp in bitmap mode

[Sergioz82]

 

 

This is a project I am currently working on.

I wanted to create a trail behind a moving sprite (the yellow sphere). The core of the idea is the classic snake concept but expanded to take advantage of the bitmap mode. I also added a "spiritual flame" effect that is triggered when the sphere is not moving. The effect is not pre-calculated as the bitmap is modified real time with random values. There is still some polishing to do (i.e improve the flame effect and the vertical trail color pattern) but now I have the proof of concept

 

I think it can be used to make projectiles, meteorities, ghosts, boat wakes and so on..

 

My idea is to make a fixed screens platformer with small puzzles to solve by using the sphere's abilities, but there is still a lot of work to do. The next step is learning XDT99 and bank switching. 

 

In more detail, the trail is made this way:

 

• the head is an empty 8x8 circle pattern with its color pattern. In each cycle the program reads from VDP the bitmap at head position, SOCB with circle pattern in next position then writes the resulting byte(s) back in VDP
• the tail has the same pattern of the head and works the same but SZCB with circle pattern instead
• the head writes position information in a buffer that has to be as long as the desired lenght of the trail, i.e 16 pixels means 16 entries in the buffer. When the head moves it writes its next position in the buffer. The tail reads the buffer in sequence.
• the bobbing effect is a very simple set of instructions that increment a -2 to 2 offset each 8 pixels
• I had to implement a collision detection between head and tail because when they overlap the tail doesn't work properly and it leaves stains on the screen, so when they overlap the head stops drawing (you can notice this in narrow turns)
• the flame effect is made by switching to an alternative head routine. It starts with a 00 byte pattern, then a random 0-255 number is generated to SOCB the pattern. Then the resulting byte is SZCB with a cutout pattern to turn off the bits around the edges to give it a rounder appereance.

 

 

 

 

[+Vorticon]

Very nice effect.

[+Retrospect]

It's great.  I love the effect.  Nice graphics too.

[Sergioz82]

4 hours ago, Retrospect said:

It's great.  I love the effect.  Nice graphics too.

Thanks

 

About the graphics I recently got my hands on a ZX Spectrum and I noticed how good the programmers worked with the two colors limitation so I tried to replicate some tricks on the TI. For example the black pixels on the wood bars.. it's incredibly simple but effective

Edited March 19 by Sergioz82

[+Retrospect]

5 minutes ago, Sergioz82 said:

Thanks

 

About the graphics I recently got my hands on a ZX Spectrum and I noticed how good the programmers worked with the two colors limitation so I tried to replicate some tricks on the TI. For example the black pixels on the wood bars.. it's incredibly simple but effective

Yeah some great graphics have been done on the Spectrum in spite of it's limitation , the same can, and has, been done for the TI.  There's one thing about the TI that makes things a little more difficult, and that is color is affected by the character sets , ie, Set 5 (64 - 71) can only have 2 colors , the Spectrum has no such limitation that way but then has no Hardware Sprites either. 

[Sergioz82]

Finally I have an update of the game

 

I still haven't got a title, for the moment I call it Will o' wisp.

 

I think I improved the flame trail effect, the previous didn't work well in vertical movement, I use two blue shades and I added some holes in the pattern to make it look more.. flamming.

 

I added a second control mode where the sphere rolls on ground instead of flying. The idea is to use it in narrow passages as shown in the video.

 

I added a status panel (still very temporary) with icons (hold fire to switch abilities)

 

And I added a dynamic map system, the player can go (almost) everywhere.

 

Next step will be adding enemies

 

 

Edited May 12 by Sergioz82

[sometimes99er]

Ooh. Very nice. 👍
 

[Willsy]

This is looking lovely!

[PeteE]

Fantastic!

[+Ksarul]

I like this so far!

[8_is_enuff]

Very cool.