Super Cars II STE: two player mode, old and new
A quick look at how two player mode has changed in the STE version. Both screenshots are from the same race, at the same moment, with the same game logic running, so the cars and weapons are all in the same places. Only the way it is shown has changed.
Original
- SC2ORIG2P.PNG (41.12 KiB) Not viewed yet
STE version
- SC2STE2P.PNG (51.42 KiB) Not viewed yet
What is different
- The original puts the two players side by side, each with a view 152 pixels wide and 148 high, with both panels across the bottom of the screen.
- The STE version puts them one above the other, each with a view the full 320 pixels wide and 98 high, with a thin black line between them.
- The panels have moved down into the opened bottom border, so they no longer take any of the screen away from the track.
- Each player now sees about 39% more track than before. You see further to the sides and a bit less up and down, so there is some trade-off, but there is more track on screen overall.
- The panels have been squashed onto fewer lines, with POS and LAPS sitting next to their figures, and the lettering is red for player one and green for player two so it is easy to tell who is who at a glance.
Why the change
- The STE version keeps the whole track in memory as one big picture and uses the STE's hardware scrolling to move the view around it. That is what lets it run at 50 frames a second instead of the original's 17.
- Hardware scrolling works on whole screen lines. Each line of the display can only start from one place in memory, so two different views side by side on the same lines is not something it can do. The original gets away with it by redrawing each half itself, which is a big part of why it runs at a third of the speed.
- Top and bottom works perfectly with it. Part way down the screen the video address is simply changed to point at the second player's part of the track, so both views scroll by hardware with no copying at all.
- Both views look into the same track picture, so a car only has to be drawn once even when both players can see it, which keeps the cost of two player mode down.
Same race, same cars, twice the width and three times the frame rate. Not bad for an old wooden panel.
