Widescreen hacks

[patbier]

Hello,

Did you have a look at the widescreen hacks ?

http://assemblergames.com/l/threads/wid ... acks.58620

4/3


16/9


I'm curious about what really changes. Any ideas ?

[cube_b3]

I read the news posts on them but other than that I don't know much.

[|darc|]

I've used Swiss to force anamorphic widescreen on GameCube before, it works well. Good idea.

[SWAT]

I think this is a hack of viewport/ratio in rendering code by one float value in memory.
It's not hardware settings, just SDK/engine param.
For every game need search special place for it, it's not universal hack for all

[patbier]

Thanks for answers,

is there a way to do the same with KOS ?

[BlueCrab]

Sure, you can do it with KOS, but how you do it depends on how you're doing the rendering.

If you're talking 3D stuff with KGL, for instance, you'd just change how you set up your perspective matrix. I think you should just need to set up your field of view to be wider with gluPerspective(), in the KGL case.

*NOTE: I don't do 3D stuff, so I might be a bit off the mark on that...

[PH3NOM]

It is good to understand the basics of Pixel Aspect Ratio (PAR) and Display Aspect Ratio(DAR).
The Dreamcast Video outputs a DAR of 4:3, i.e. 640x480.
The "Widescreen hack" changes the PAR and expects the TV or monitor will do the work of stretching the 4:3 image to 16:9, at 480p that would be ~853x480 display.
Think of it as writing to a 853x480 framebuffer, then scaling the 853x480 framebuffer down to 640x480 for video output by the PVR.
Then, the TV will stretch the 640x480 image back to 853x480.

Notice that is why we actually see more of the world to the left and right of the characters in the screens you posted there.

And BlueCrab is right, in 3D vertex submission, the only difference is the perspective matrix.
That is how I enable the option in my game engine:
viewtopic.php?f=29&t=102506&p=1047897#p1047897

But my guess is you do not transform your 2D vertices, submitting your sprites in the range of (0->640 , 0->480)

Basically, you need to scale your vertices' x component so that when stretched out by your TV into WideScreen, your desired pixel ratio is preserved.

One way to do this would be to re-organize your sprites for a 853x480 display.
Then, when submitting the vertices, do a simple transform on the x component like:

Code: Select all

x = (x * 640.0f) / 853.0f

To scale the vertices from 0->853 back to 0->640.

[bogglez]

Any comment on how this affects anti-aliasing?
The DC will anti-alias horizontally, so I was wondering how stretching the image horizontall affects AA of edges.