Azurik: Rise of Perathia
Known tricky behaviour
Skinning code / Shader rounding mode
This game depends on correct GPU rounding. If an emulator suffers from issues with non-exact rounding in the shaders which do the skinning / skeletal animation the character models will be very broken.
IIRC Code is like:
A0 = c.x + c.z = 18 *do stuff with c[96+A0] to c[98+A0]* A0 = c.x + c.z = 21 *do stuff with c[96+A0] to c[98+A0]* A0 = c.y * v2 *do stuff with c[96+A0] to c[98+A0]* c is vec4(15, 765, 3, 0). 765 = 3*255. v2 is GL_UNSIGNED_BYTE, normalized => v2 = raw/255. A0 = 765 * raw/255 = 3*raw.
This should all be working, but it's not. NV2A/Vertex Shader does round-to-zero. Behaviour for GLSL and other modern graphic APIs is undefined..
To work around this rounding issue
A0 += 1.0/255.0 can be used as a temporary hack