[Render] RGB565 VQ Alpha - (Some sprite in Powerstone 1/Shenmue 1 appears with alpha)

[BenoitAdam]

These kind of sprite in Powerstone 1 appears with black alpha

Should be :

NullDC4Wii :

[BenoitAdam]

RGB565 was already fix (Ryo's eyes see #24 and chuchu #52 )

VQ Compression is the difference here

[BenoitAdam]

Implemented a hack :

Option C – Implement colour‑key transparency for RGB565

static u16 ConvertPixel(u16 p) {
    // If the pixel is black (or any chosen key), mark it transparent
    if ((p & 0xFFFF) == 0x0000) return 0x0000; // RGB5A3 transparent
    // Convert RGB565 to RGB5A3 with alpha=1 (opaque)
    u32 r = (p >> 11) & 0x1F;
    u32 g = (p >> 5)  & 0x3F;
    u32 b = p & 0x1F;
    return 0x8000 | (r << 10) | ((g >> 1) << 5) | b; // approximate 5:5:5 with 1-bit alpha
}

But better option is A :

Option A – Correct the format detection for VQ textures

[BenoitAdam]

Option A :

checking ta_struct.h, seems something isn't right

[BenoitAdam]

ta_struct.h updated :

acb3942

[BenoitAdam]

I didn't succeed making the "right way" (option A) but since the bug is fixed I'm closing it for now

If you wanna dig more :

https://claude.ai/share/3f7bc401-881c-4c85-91ce-72a5ed4378e0

[BenoitAdam]

Downfall : some black element could appear transparent. May need to implement a global preset

[BenoitAdam]

Same problems was in Shenmue 1 (happens quicker, better for testing)

[BenoitAdam]

shenmue isn't the same problem

problem reappeared afet AGBR1444 fix

will fix in 0.35

[BenoitAdam]

it's possible to revert the hack since we reverted this issue

need to compare performance

#67