Two lines...not quite worth a whole new download, as I bet the parent ID still isn't set yet.

This fixes all distortion...I believe.

ors.vc
Incrementing across the X axis [inner loop]
Comment out/delete lines 82-83.

Before the SetPixel line, add:

if (srcX<0) srcX=width<<8+(srcX%(width<<8));

if (srcY<0) srcY=height<<8+(srcY%(height<<8));

Comment out lines 60-61.

Fixing distance divide by zero and integer truncation
At line 36 [compute distance], delete and add:

distance = Mode7_spaceY>>2*(Mode7_scaleY>>2)>>4 / (desty+Mode7_horizon);

if (distance == 0)

     {

     distance = Mode7_spaceY>>2*(Mode7_scaleY>>2)>>4 / (desty+Mode7_horizon+1);

     }

I'm working on some improvements. I've fixed the centering of rotation, and I'm working on a type of mip-map system. I could possibly do Trilinear Mip-map Filtering like the N64, but I'm not sure if it would help the quality...At such a low resolution that I run the demo at, the mipmap isn't able to fix the very distant artifacts.

After I finish the mipmap/filtering thing, I'm going to try to remake it to use RotScale rather than SetPixel, which might be a bit faster...not yet sure.

I have an idea to create a full 3D sprite/object rotation library, but I can't quite integrate this demo into it [since I only partially understand the maths]. So I'm going to compromise and use the sample sprite functions given in the Allegro/Sin & Cos: Programmer's Pals tutorial. At that point, I'd probably release this and call it complete.

FPS = Crap

I'm working on an FPS counter, and after I get out for thanksgiving break, I'm going to recode it, now that I've got an idea what I'm doing, so I can improve the speed.

At this second though...

500x500 buffer = < 1 frame/sec
300x300 buffer = > 1 frame/sec [but not more than 5]
200x200 buffer = approx 10 frame/sec, I guess
100x100 buffer = maybe about 30 fps.

I really don't mind the low-res speed...I've got to work on improving the math a bit. For example, the GBA has only something like a ...200x140 pixel screen or somesuch, but we can all agree that Mario Kart GBA Mode7 is a lot cleaner than the same 200x140 buffer on this demo...it needs tweaking.

Quote:


Aren't Mode7-type effects on the GBA done through hardware(probably not called "Mode 7" on the GBA), similar to how Mode 7 worked on the SNES? If that's the case, you really can't compare software-based Mode 7 to hardware-based. ;)

But I'm sure there's a way to do it in software at high speeds, so I hope my words aren't discouraging.