2 Questions

JS Lemming · Post by **JS Lemming** » Tue May 16, 2006 8:45 pm

First, is it really worth it to allow the user to adjust the screen dimensions in my games? Like to account for the TV cutting off the edges of the display? I already coded it but I'm beginning to think that it might not be worth the extra time it takes to calculate the adjustments for all things drawn. Is it just my crazy old German TV that cuts so much off the edges? Or is it a common problem?

Secondly, how many of you devvers use time to move objects rather than brute pixel amounts per frame? Is it worth it to move objects with time even though all DCs are pretty much alike? Are there super benefits either way besides the brute force approach being easier?

Vlame · Post by **Vlame** » Tue May 16, 2006 8:54 pm

I really appreciate the thought of the programmer who puts the "Adjust Display" in the options, with every game that has it, I have to adjust it so it fits perfectly.

JS Lemming · Post by **JS Lemming** » Tue May 16, 2006 9:10 pm

Well, I think I'll keep it then. And I'll make sure that all games I create will use the same VMU file to store the adjustments. That should save people aprox. (20*(numerOfGamesIMake - 1)) seconds of their life!

BlackAura · Post by **BlackAura** » Wed May 17, 2006 2:00 am

If this is for a 2D game, I wouldn't consider it to be worth it. Just make sure that the game works well on TVs with lots of overscan, and that important displays (life counter, for example) aren't hidden off the edge.

The main problem is that you can't stretch the display of a 2D game without causing distortion. If you're using the PVR to do hardware rendered sprites, that distortion will enable bilinear filtering, and make everything look blurry.

On the subject of time, it really depends on your game, and where you expect it to run. If you're sure it'll only ever be running at one specific framerate (say, 60Hz), then using a fixed step per frame is fine. If the framerate will ever change (say, using it on a PAL Dreamcast and ending up with 50Hz), then it's not good enough. You either need a framerate independent system, frameskipping, or to put up with the game running slower.

JS Lemming · Post by **JS Lemming** » Wed May 17, 2006 11:08 am

Yes, this is a 2D game.

BA wrote:If you're using the PVR to do hardware rendered sprites, that distortion will enable bilinear filtering, and make everything look blurry.

Now this confuses me a bit. Can you give me an example of how to draw something not blurry? Do you just draw something on screen with the exact dimensions of the texture? Does that mean that I'm not allowed to draw sprites with rotation or scaling?

Thanks for the help btw.

BlackAura · Post by **BlackAura** » Thu May 18, 2006 12:11 am

If you have a sprite that's 32x32 pixels, stored in a 32x32 pixel texture, and draw it into a 32x32 rectangle on the screen, there will be a 1:1 mapping between the pixels in the texture and the pixels on screen, so the image will be reproduced exactly.

If you double the size of the rectangle you're drawing to, there isn't a direct relationship between texture pixels and screen pixels anymore, so the Dreamcast is forced to use texture filtering. The same thing will happen if you change the size of the drawn version by even one pixel, or rotate it, or distort it in any way. Depending on the artwork, this might be unnoticable, or it might totally ruin it.

If you're doing rotation and scaling anyway, then it's probably not worth worrying about. You would have already noticed if your artwork looks bad when using bilinear filtering. Artwork in the style of 8- or 16-bit games tends to look horrible when filtered, because the sharp transitions between different colours become blurred. Larger, more natural looking artwork without sharp colour transitions tends to look fine - you won't even be able to tell when it's doing filtering.

Phantom · Post by **Phantom** » Thu May 18, 2006 5:52 am

I've never been able to get the PVR to give me a 1:1 mapping. I assumed it would always filter even if the image happened to be the exact 'right' size. I guess I'll have to give that another shot.

carbon14 · Post by **carbon14** » Thu May 18, 2006 8:57 am

On your question about the whether it's just your tv that cuts things off the screen.

I'm only just getting to grips with NTSC, because I'm in the UK and I have PAL.

Everything fits on my PAL screen, but NTSC seems to lose quite a lot at the top and bottom, and that just seems to be the way it is. If you look at a lot of games, they try to avoid putting important stuff at the top and bottom of the screen, either with thick borders, or with gameplay elements that are less important.

I tried resizing the screen for NTSC and it just looked ugly, because my textures were designed to fit nicely pixel for pixel, the distortions were really distracting. In the end, I have just moved gameplay elements up from the bottom of the screen, and down from the top. It's irritating, but I can't see a better way round it.

If I was doing a 3D game, I would probably change the viewing frustrum so that I actually showed a bit more at the top and bottom of NTSC screens, and expected it to get cut off, but that's not really an option with 2D stuff.

Also, my game is slightly easier on PAL, because it runs 5/6ths of the speed.

JS Lemming · Post by **JS Lemming** » Thu May 18, 2006 10:23 am

My TV cuts so much off all the edges that it just isn't funny. We're talking a good 30 pixels on the left and a little less on the top and bottom (none on the right oddly). That's too much for me.