Clipping

Tuesday, 27th June 2006

Clipping (adjusting walls to ensure that they are in the field of view so that they can be drawn correctly is being a right pain).

Firstly, I rewrote some of the really ugly wall-handling code:

Clipping follows the fairly simple maths:

(Where m is the gradient of the wall). The resulting Clip value then corresponds to the new (X,Y) coordinate - if you want to clip to x=-y all that's needed is (1 - m) becomes (1 + m) and Clip must be negated before using it as the new X coordinate.

The result (with added adjustment layer to turn the grey clipped line into red for clarity's sake) seems to work pretty well.

...or not. When implemented with the rest of the code, something goes rather wrong when I look at the wall from the wrong side. Thankfully, that was a simple bug in the division routine, causing it to trash the accumulator when one of the operands was negative (the accumulator itself formed part of one of the operands).

With that fixed, things look a bit more positive, but it's still rather unstable.

Latenite 1.0.6.0

Tuesday, 20th June 2006

There's a new Latenite beta - 1.0.6.0 - available from my site. I hope this is the last Latenite 1 release; I'm moving away from the current IDE towards a revised Latenite 2, the focus more on interactivity with the assembler and the debugger (better 'Intellisense', breakpoints, variable watching and so on). This mainly revolves around a much improved text editor, currently in the works.

Not a very exciting thing to look at, but handling text selection, editing, copying, pasting, and highlighting - and keeping it fast - is being a bit of a pain.
For the most part, it is fast enough, but gets seriously sluggish when scrolling up and down at high resolutions (has to repaint the entire control as none of it is buffered).

That little 3D engine for the calculator I was working for (codenamed Nostromo) is not dead, as you might have thought;

(Old screenshot to refresh your collective memories). I have recently 'ported' the TASM-style code to the new Brass syntax, rewritten all of the wall handling code for increased performance and fixed some of the graphical glitches caused by overflow (lines wrapping incorrectly around the display). I have increased the resolution and accuracy of the maths in use as well, but it's still pretty sluggish with large amounts of data and still lacks occlusion and wall clipping to the view.

One (easy) way of speeding things up would be to split the world up into 'rooms' (or zones, pick whatever terminology you like) where each room is entirely self-contained and cannot be seen from any other room. By opening and closing doors between rooms you can add and remove which rooms are in the list to be drawn, keeping the geometry count low.

Of course, for this to work, I'd need a bit of collision detection to be able to work out which room the camera is in.

In terms of occlusion, I'm a bit stumped. As far as I can tell, BSP might be the way to go, but have never been able to write a working 'BSP engine'. If anyone had any links they'd recommend on the theory and implementation behind this, I'd be very grateful.

Text Editing Woes

Thursday, 15th June 2006

I've had enough of my syntax-highlighting text editor in Latenite (it's a hack on top of the RichTextBox control, using all sorts of ugly Win32 hacks to beat it into submission). I'd much rather have a control I had some... 'control' over, so have taken to writing my own custom control.

One useful thing is that it supports Unicode characters nicely, unlike the RichTextBox

It doesn't currently support text selections (which is a bit of a problem) but once that's added it should be simple enough to start adding goodies to it that weren't easily possible via the RichTextBox control (reliable line highlighting, tab width manipulation, whitespace glyphs, collapsing code blocks and so on).

Applications

Wednesday, 7th June 2006

I've been attempting to add native TI-83+/TI-73 application support to Brass. Testing with Flash Debugger has been an entertaining experience, not least thanks to helpful messages like:

I haven't managed to get a signed application running in Flash Debugger or on hardware yet - I suspect the header is wrong - but seeing as the demo application has a different header structure to what the header generator creates, and both have generally conflicting information, I need to find some better resources.

If you want to sign applications from C♯ via Wappsign, this wrapper around the COM object might be useful. You'd use it like this:

// Sign the app (where BinaryFile is the filename of the .hex file to sign)
try {
    
    AppSigner Signer = new AppSigner(AppSigner.Mode.DetectType);

    // Get the key file
    string KeyFile = Signer.GetKeyFile(BinaryFile);
    if (KeyFile == "") throw new Exception("Couldn't find the key file.");

    // Get the output filename
    string SignedAppFilename = Signer.FormatOutput(BinaryFile);
    if (SignedAppFilename == "") throw new Exception("Couldn't establish output filename.");

    // Sign the bugger
    int Signed = Signer.Sign(BinaryFile, KeyFile, SignedAppFilename);
    if (Signed != 0) throw new Exception(Signer.GetErrorMessage(Signed));

} catch (Exception ex) {
    // Didn't work as it should
    DisplayError(ErrorType.Error, "Could not sign application: " + ex.Message);
}