I was talking to Deep earlier about masked sprites. I learned that to create a masked sprite, you need to:

(1) create a white-background-ed sprite
(2) create a black background
(3) xor the sprite with the background to create the mask
(4) AND the mask to the screen
(5) OR or XOR the sprite to the screen.

So now, if I wanted to do 4-layer greyscale, would I essentially need to have 4 images layers, two for each buffer, and do this process once on each?

Do you mean 4-level grayscale? If so, you just need 3 layers of sprite data (eg. an 8x8 sprite would be 3*8=24 bytes of data)

The first 2 layers are just normal grayscale data, and the 3rd layer is the mask.

In this example, the red is transparency.


Code:

And if I understand correctly, I AND the mask to both buffers, then write the sprite itself to each buffer?

I haven't written my own masked sprite routine for ages, but if I remember correctly you would CPL and then AND the mask byte with each buffer, and OR the "dark level" byte to the dark buffer and the "light level" byte to the light buffer

What's CPL? Sorry, I'm awful with graphics stuff.

Secondly, I used Badja's sprite scaling routine (which I posted in below for reference), and the ability to scale sprites is important. First off, the scaled sprite routine uses XOR or OR logic, not AND, so it would need to be changed to do the mask. Secondly, is there a way to do both buffers at the same time, and only call the routine, say, twice?


Code:

CPL is complementary, so like xor $FF, the asm command to cpl the register a is simply cpl

Response to trip1ea:

I actually call that routine 4 times in my original code, but if it can be modified to call twice or even once, that would be great. Or even if I can call it once pointing to the mask, and once to load in the greyscale layers, that would be perfect. I'll be back tonight to play around with it some... but it would be a big help if someone could just fill me in as to what part of that routine scales and what part actually renders.

bump!

Well, I'm officially stuck here...

_SS_RowLoop is where the rendering begins. Also, the edits I made and linked to you earlier only does one layer of the sprite. (mask the first time, draw the second time).

Btw, rather than cpl the mask, just store it already cpl'd. Instead of
Code:
use:
Code:
I'm not sure how scaling a mask would work, though.

chickendude, Zeda was kind enough to help with that, so its done. The only coding remaining in this project is:

1. Map generator.
2. Making the rendering engine render objects with farther objects behind closer ones (rather than in the order they occur as it is currently). For this, i was thinking some sort of shunting yard sorting.