Based on Street Fighter II, engineers explain what was superior about the arcade board 'CPS-1' at that time.
Street Fighter II, paper trails
https://fabiensanglard.net/sf2_sheets/index.html
The arcade game board that appeared at the same time as the arcade game ' Lost World' released by Capcom in 1988 is 'CPS-1'. Street Fighter II was also released on this CPS-1.
The CPS-1 has innovative graphic rendering capabilities compared to previous arcade cabinets, and one of the secrets was that it supports layers. CPS-1 can output 16 x 16 dot 'tiles' (so-called sprites ) as layers, and Street Fighter II expresses characters with this combination of tiles.
Ryu's victory pose is 29 tiles
Sagat's tiger uppercut has 30 tiles
Edmond Honda's jump pose is 45 tiles
Chun-Li's stance pose is 25 tiles
With CPS-1, you can perform basic operations such as flipping this tile horizontally or vertically and changing the color, but you cannot rotate or scale it. However, the number of tiles that can be displayed per frame is enormous, and according to Mr. Sangrad, 'the maximum number of tiles that can be displayed per frame is reported to be 256.'
In Capcom's arcade game 'Punisher ' released on the same CPS-1, a huge boss character 'Kingpin' represented by 80 tiles will also appear.
'It was a blessing for the graphic artist, but it was also a problem for the project manager,' said Sangrad, who said that the CPS-1 had very good graphics capabilities. At that time, ROM chips were very expensive, so it seems that ROM budgets were allocated to each game development. In addition, it seems that the number of tiles that the graphic artist team can use was decided by ROM size / tile size.
CPS-1 operates in four layers, 'SCR1', 'SCR2', 'SCR3', and 'OBJ'. 'OBJ' is the layer for expressing the character, and the rest are the layers for expressing the background and foreground. is. In the case of Street Fighter II, the ROM budget is 6MiB, and 4.6MiB, which is 75% of the total, is allocated to OBJ. The graph below shows the percentage of memory allocated to each layer.
At that time, Capcom managed the graphics that can be used in arcade games using CPS-1 with paper sheets, and in the case of Street Fighter II with a capacity of 4.6 MiB, it seems that 144 sheets can be used. .. In other words, you have to express all the characters with 144 sheets.
The graph below summarizes the number of sheets used by each character, and the character using the most sheets is 'ZAN' with 19 sheets. Below, 'HON (Edmond Honda)' 15 sheets, 'BLA (Blanka)' 15 sheets, 'DHA (Dhalsim)' 14 sheets, 'RYU (Ryu)' 13.5 sheets, 'GUI (Guile)' 11 sheets, 'CHU (Chun-Li)' uses 10 sheets. In addition, 9 sheets for Vega, 6 sheets for Sagat, 6 sheets for Bison, 6 sheets for Balrog, and 3 sheets for Ken will be used.
One sheet has 16 squares x 16 squares below, and 1 square = 1 tile.
Ken is represented by just three sheets because Ken is designed to divert many of Ryu's tiles. Therefore, Ryu and Ken all use the same color except for their clothes and face.
For example, Ken's victory pose is output by converting the white part of Ryu's victory pose to red and replacing the face part with Ken.
The seat savings are fairly detailed, for example, in a pose with the sagat facing forward (center at the bottom of the seat), the left foot can be represented by flipping the right foot, so only the left leg tile exists. I will not.
Mr. Sangrad contacted to talk to the game creators who have been working on game development on CPS-1, but since all of them failed, it is more than how CPS-1 was programmed. He said he couldn't know the details. Still, Mr. Sangrad does not seem to give up the opportunity for an interview yet, 'If you have experience developing games with CPS-1, or if you can contact them, please contact me. ! ”.
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in Game, Posted by logu_ii