Having followed the many discussions on here and STH regarding sprites and how best to display and update them, I wonder if the experts on here could comment on the following. I'll just make a statement based on my understanding and then you can all tear it apart accordingly....
The TV/Monitor display is only 'repainted' every 20ms and so, to reduce or eliminate flicker, we use an interrupt which occurs at, or somewhere just before, the end of frame to cue our sprite movements. Since we also know that the smoothest movement will be obtained with single pixel increments (or maybe 2 pixels to simplify Mode 2), this then seems to define a finite upper limit for the maximum speed that a sprite can move.
For example, if we consider a simple left-to-right 'base' such as in Space Invaders or similar and slightly compromise with two pixel movement in Mode 2 then there are 80 possible lateral positions for the base (slightly less due to the width of the base). So, with a Left/Right key held down, if we only move it once every 20ms, the minimum time it will take the base to move from one side of the screen to the other is therefore 1.6s.
I presume then that if we need sprites to move around quicker than this, the only option is to increase the number of pixels moved in 20ms. There would be no benefit in keeping the 1 or 2 pixel resolution and decreasing the interval since the maximum visual display update is governed by the 50Hz display.
Basically then, is the above statement correct or have I missed something ?
Martin
), Rich has (thankfully!) published tons of priceless info here and on STH about sprite plotting routines but to avoid running before walking, is there a good all round definitive plotter/eraser for Mode 2 with an accompanying screen address calculator? (or is there no simple answer to that..?) I have some generic routines that I plucked from TMU many years ago but I suspect they're not particularly efficient.
Correct file uploaded. I've re-downloaded and checked it this time... 