4 bit texture bug

[Ian]

This one was found by model123





This is what the raw (decoded) texture looks like


So it looks like are textures are perfectly inverted ....

[HarryTuttle]

That's another case that made me mad since last year... the fix would be to invert the "c" value like in this code snippet:

Code: Select all

case 10:   // high byte, low nibble
  for (yi = y; yi < (y + height); yi++)
  {
    for (xi = x; xi < (x + width); xi++)
    {
      texel = src[yi * 2048 + xi] >> 8;
      c = (texel & 0xF) * 17;
      c = 255 - c; // Breaks ECA, Harley but fixes Daytona 2 decals
      scratch[i++] = c;
      scratch[i++] = c;
      scratch[i++] = c;
      scratch[i++] = c;
    }
  }
  break;


However breaks some textures in Harley (and others) like the big green street sign at the beginning of the demo... The thing is that alpha channel should always be inverted, but rgb values depends on something else... I'm preparing some screenshot I'll post here

[Ian]

Code: Select all

   case 10:   // high byte, low nibble
      for (yi = y; yi < (y + height); yi++)
      {
         for (xi = x; xi < (x + width); xi++)
         {
            texel = src[yi * 2048 + xi] >> 8;
            c = 255 - ((texel & 0xF) * 17);
            scratch[i++] = c;
            scratch[i++] = c;
            scratch[i++] = c;
            scratch[i++] = (c == 0 ? 0 : 255);
         }
      }
      break;

The 4 bit textures use a special value 255 to indicate 1 bit transparency

[Ian]

But yeah .. inverting the texture breaks the signs
There must be some flag in the poly header that inverts the texture

[HarryTuttle]

Good Daytona 2 decals:

du2_01.jpeg (242.64 KiB) Viewed 10086 times

Bad Harley:

hl_01.jpeg (241.19 KiB) Viewed 10086 times

Bad ECA:

eca_01.jpeg (236.47 KiB) Viewed 10086 times

I checked for any connection with translator map bit and/or translator offset values but nothing...

[Ian]

Might have to use barts bit analysis tool

[HarryTuttle]

...and there's also this, as someone noted in another forum (left Supermodel, right Abe's footage):

du2_02.jpeg (236.5 KiB) Viewed 10083 times

that's however an animated texture.

[Ian]

That's not a 4bit texture is it?

[HarryTuttle]

That's not a 4bit texture is it?

Yes it is, it's composed by three types: 1,2 and 3 precisely (so not contour)

[Ian]

It can't be a 4bit texture, because it works in the legacy engine. And countour is always specified for 4 bit textures. Took me a long time to figure that out :p