Scanline effects: Difference between revisions

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[[File:kof98rli.gif|frame|[[The_King_of_Fighters_%2798_-_The_Slugfest]] moves the fist sprites horizontally in its intro to create a "bad sync" effect. Looks like it's animated with a multiplied constants table ?]]
[[File:Sengoku2persp.png|frame|[[Sengoku 2]] changes the shrinking and the position of a scrolling sprite block in its intro to create a mirror and perspective effect.]]
[[File:Sengoku2persp.png|frame|[[Sengoku 2]] changes the shrinking and the position of a scrolling sprite block in its intro to create a mirror and perspective effect.]]


'''Scanline effects''' are special tricks using the [[68k interrupts|raster line interrupt]] to distort [[sprites]] horizontally or vertically.
Scanline effects are special tricks using the [[timer interrupt]] to distort [[sprites]] by updating their coordinates or shrink values mid-screen.


These effects are very CPU consuming as they can be triggered at very tight intervals during active display. Consequently, they may have to use tables of precomputed values (constants, or calculated during the VBlank) to be applied fast enough.
These effects can be very CPU consuming as they can be triggered at tight intervals during active display. Consequently, they may have to use tables of precomputed values (constants, or calculated during the VBlank) to be applied fast enough.


[[Neo Turf Masters]] relies exclusively on this effect to render the playing field.
[[Neo Turf Masters]] and [[Riding Hero]] heavily rely on this effect to render the playing field.


[[Category:Code]]
[[Category:Code]]
[[Category:Video system]]
[[Category:Video system]]

Revision as of 23:01, 17 January 2016

File:Kof98rli.gif
The_King_of_Fighters_'98_-_The_Slugfest moves the fist sprites horizontally in its intro to create a "bad sync" effect. Looks like it's animated with a multiplied constants table ?
File:Sengoku2persp.png
Sengoku 2 changes the shrinking and the position of a scrolling sprite block in its intro to create a mirror and perspective effect.

Scanline effects are special tricks using the timer interrupt to distort sprites by updating their coordinates or shrink values mid-screen.

These effects can be very CPU consuming as they can be triggered at tight intervals during active display. Consequently, they may have to use tables of precomputed values (constants, or calculated during the VBlank) to be applied fast enough.

Neo Turf Masters and Riding Hero heavily rely on this effect to render the playing field.