Originally posted by
Jim Sachs:
Memory usage, collision avoidance, and especially frame rate are all major factors. Yes, I know that Dream Aquarium does this, but it makes sacrifices that I am not willing to. Even with the minimum amount of fish, the frame rate of Dream Aquarium is extremely low on my computer. I assume this is because the author came from the film industry, where it's OK to take all day to render a frame. Coming from the gaming industry, my main priority is speed and smoothness. I don't know what is causing the slowdown, since Alan has done a wonderful job at keeping the polygon count down. It's possible that his highly effective collision-avoidance and schooling routine is simply a WHOLE LOT of code.
It's the many transparent layers (i.e. the plants and light rays) that make Dream Aquarium run slow on older hardware. MA doesn't have as significant graphics-card requirements because it has a fairly simple (yet effective) tank with minimal transparency. On good graphics hardware i've found DA generally runs more efficiently than MA because of other optimizations i'm doing. For instance, on my laptop (3 yrs old) at 60fps i get only 25% cpu use in Dream Aquarium whereas Marine Aquarium needs 85% of my cpu for the same frame rate. It depends entirely on your particular hardware setup. Probably in both screensavers the fish calculations themselves are negligible. When not sending polygons to the graphics card, D.A. uses under 1% cpu. While i do come from the cpu-wasteful film industry, i also come from the commodore 64!
A big killer of cpu cycles is something called Vertical Sync, where your cpu has to wait (unfortunately burning cycles) until exactly the right time to display the next frame of animation. Sadly it seems to be unavoidable if smooth playback is desired.
cheers,
alan