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DigiTan
Unregistered HyperCam 2
Super Elite (Last Title)
Joined: 10 Nov 2003
Posts: 4468
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 Posted: 05 Sep 2009 05:23:01 pm Post subject: |
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| Back in the day I had an idea of adjusting the contrast up and down for graphical effects, fade in/fade out, night levels, etc. For some reason, I could never get it to look right on TI-82. Maybe this had more to do with the contrast emulation behind VTI, but it got me thinking of trying it again. It certainly isn't very common. How would this work for 83+? |
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calc84maniac
Elite
Joined: 22 Jan 2007
Posts: 770
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| Posted: 05 Sep 2009 05:27:14 pm Post subject: |
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| Well, I think the 83+ and the 83+SE/84+/84+SE have differing contrast levels in general (the 83+ is much lighter for the same contrast value, iirc). |
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DarkerLine
ceci n'est pas une |
Super Elite (Last Title)
Joined: 04 Nov 2003
Posts: 8328
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| Posted: 05 Sep 2009 06:23:09 pm Post subject: |
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| I don't think this is a good idea. People generally adjust contrast levels to personal preference and forcing them to look at the screen at a suboptimal level is just mean. |
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calc84maniac
Elite
Joined: 22 Jan 2007
Posts: 770
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| Posted: 05 Sep 2009 06:45:54 pm Post subject: |
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| You could always have a simulated contrast effect with a couple of levels - like if you want it a bit darker, you could OR alternating checkerboard patterns to each byte in the fast copy routine, or AND them to make it lighter (may require two screen updates per frame) |
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FloppusMaximus
Advanced Member
Joined: 22 Aug 2008
Posts: 472
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| Posted: 05 Sep 2009 08:15:31 pm Post subject: |
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I think you could probably create some interesting temporary effects by varying the contrast - e.g. a sudden bright light simulated by dimming the entire screen. I would certainly be sure to do so relative to the user-specified contrast value.
I think permanent effects (such as night/day, outside/inside) are also possible, but don't go overboard with them - only adjust the contrast by a few units in either direction, enough to create a visible effect but not enough to seriously affect the screen's legibility. |
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DigiTan
Unregistered HyperCam 2
Super Elite (Last Title)
Joined: 10 Nov 2003
Posts: 4468
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| Posted: 26 Sep 2009 09:10:49 pm Post subject: |
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| Exactly how do you change the contrast on 83+ anyway? Screen port? |
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FloppusMaximus
Advanced Member
Joined: 22 Aug 2008
Posts: 472
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| Posted: 26 Sep 2009 09:21:40 pm Post subject: |
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It's the same as on the 82. Write a value between C0h (lightest) and FFh (darkest) to port 10h.
The OS doesn't use the entire contrast range - it adds a fixed offset to the contrast value before outputting (18h, perhaps? It's documented in the SDK, I think.) |
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calc84maniac
Elite
Joined: 22 Jan 2007
Posts: 770
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| Posted: 26 Sep 2009 09:47:06 pm Post subject: |
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FloppusMaximus wrote: It's the same as on the 82. Write a value between C0h (lightest) and FFh (darkest) to port 10h.
The OS doesn't use the entire contrast range - it adds a fixed offset to the contrast value before outputting (18h, perhaps? It's documented in the SDK, I think.)
I haven't noticed any difference between the bottom $18 values (they all seem to be the lightest). |
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DigiTan
Unregistered HyperCam 2
Super Elite (Last Title)
Joined: 10 Nov 2003
Posts: 4468
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| Posted: 30 Sep 2009 05:06:08 pm Post subject: |
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| Might as well try it out then. Will probably make the changes temporary to avoid the annoyance factor. |
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