[Coco] My humble Coco3 sprite project update

[Hugo Dufort]

Hi! I would like to that the people who have helped me getting on track 
with the Coco3 memory map, GIME and ASM. My humble Coco3 project is 
showing some results, which I can post online. For now it will only be 
screenshots, but eventually I'll post some videos as well. Here is what 
I have accomplished so far:
- understand and use the hi-res graphics modes of the Coco3, set 
palettes, map memory pages, etc.
- define and decode raster images using Base64 directly in the ASM code 
(this memory block can be reused once the images are extracted and 
packed to another area in memory)
- create Buffer structures (fast-rendering bitmaps with no transparency)
- create Sprite structures (fast-rendering bitmaps with transparency)
- create TileSet structures (very fast-rendering 8x8 tiles)
- render buffers, sprites and tiles
- animate sprites using buffers

I have implemented, then abandoned my palette mask trick -- it was 
faster than my current sprite technique, but not by much. I currently 
use an optimization technique that interleaves the bitmap and its mask, 
which allows me to load 2 pixels and their mask in each loop using a 
single pointer. With the whole rendering loop working in A,B,X,Y (and 
sometimes U), no need to push/read the stack.

Right now I am working on page flipping and learning some addressing 
modes of the 6809 that are still a mystery to me!

Here is my first screenshot:
http://avantrad.ca/upload/hugo/coco3sprites1.png


Hugo Dufort



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