Viewport scaling

It's been a fairly slow week for progress on Daedalus. I've had a few busy days with work, and I was away over the weekend so I've not had much time to work on Daedalus since my last update.

One thing I have managed to implement is viewport scaling however. After the previous release I received an email from Chris Meyer-Rassow which had a couple of interesting points. He suggested that I should have a look at providing a setting to allow the emulator to run with an aspect ratio of 4:3, rather than strecthing everything to fit the PSP's 16:9 (or 15.88236:9 to be accurate :)

I had been meaning to add this option for some time, and as it was only a small change I decided to implement this feature for the next release. I've added 3 different modes, as shown the in screenshots below. The first mode simply scales the graphics up to fit the PSP's screen (this is no different from the current release of the emulator):



This renders at 480x272. Notice how the vertial lines for the 't' and 'f' characters look slightly too heavy. This is as a result of scaling the graphics up to fit the PSP's screen. (As an aside, this screenshot clearly shows another issue that I need to address - the zfighting which is clearly visible in the carpet. I have a couple of ideas for fixing this.)

The next shot shows the same scene with the new unscaled 4:3 viewport setting:



This renders at 320x240, and so avoids scaling up any of the graphics. You can see that the problems with the 'f' and 't characters has gone. On the downside, there's a lot of 'wasted' space around the screen.

The final settings shows the new scaled 4:3 viewport setting:



This maintains a 4:3 ratio (so we maintain the correct aspect ratio), but scales things up to 362x272 to make full use of the screen's height. We waste a little less space with this mode, but some of the original problems with the text are still visible.

In the end all three options are a trade off between making full use of the screen and quality. In the next release it will be possible to adjust this setting as the emulator is running so you can pick whichever one looks best for the rom you're currently running.

As a result of doing this work with the viewport, I also fixed a couple of bugs related to how I was emulating the N64's viewport. When I originally wrote the graphics code for the PSP version of Daedalus, I forgot to handle the N64's viewport scaling/translation, which causes problems rendering certain scenes, as demonstrated in Aerogauge below:



Notice how the car is being rendered off-centre (it should be in the top right hand corner). After my viewport fixes, the same scene now looks like this:



The same change also fixes various minor glitches in a number of other roms (including Mariokart and Waverace), so it's a nice bugfix to get in for the next release.

-StrmnNrmn