For some reason Model 3 uses vertex coordinates rather than texel coordinates to calculate mipmap levels
Revised microtexture implementation; results are very close to real hardware when running at native resolution with supersampling disabled
The old texture code was being bottle necked by the texture reads. We mirrored the real3d texture memory directly, including the mipmaps in a single large texture. I *think* most h/w has some sort of texture cache for a 2x2 or 4x4 block of pixels for a texture. What we were doing was reading the base texture, then reading the mipmap data from a totally separate part of the same texture which I can only assume flushed this cache. What I did was to create mipmap chains for the texture sheet, then copy the mipmap data there. Doing this basically doubles performance.
Should stop the sky flashing in lemans24, and the background totally disappearing in sega rally after a game. The logic here is still not totally understood but works well enough for the games.
Late christmas present. Due to the way alpha works on the model3 adding regular anti-aliasing doesn't really work. Supersampling is very much a brute force solution, render the scene at a higher resolution and mipmap it.
It's enabled via command line with the -ss option, for example -ss=4 for 4x supersampling or by adding Supersampling = 4 in the config file.
Note non power of two values work as well, so 3 gives a very good balance between speed and quality. 8 will make your GPU bleed, since it is essentially rendering 64 pixels for every visible pixel on the screen.
The two transparency layers, might not be separate layers at all. We believe the hardware is writing each layer to every other pixel (stipple alpha), then using an anti-aliasing filter to effectively blend the pixels. Because the pixels don't overlap they don't depth test against each other. We are using separate layers to emulate this, so the depth buffer must be saved and restored between the layers.
If two translucent polygons with opposing patterns overlap the result is always opaque
Also the LOD scale calculation depends on Euclidean distance of x, y and z, not just z
The stencil mask must be set to all 1s otherwise we can't clear all the bits in the stencil buffer. Also we no longer need to save/restore the depth buffer into between priority layers.
Scroll attenuation seems to disable ambient fog. If scroll attenuation is enabled it's telling the h/w to draw the real3d spot light on fog for the scroll fog layer. This should fix a regression where the background disappears on sega rally.
The attenuation value effects the spot light on fog for the scroll fog layer. The old implemention was nearly correct but the paramaters for the mix function were swapped.
- Scroll fog needed a break statement otherwise it could draw potentially multiples times.
- The fog atttenuation paramater doesn't appear to effect scroll fog, other than to potentially enable it. This fixes some issues with emergency call ambulance.
- Added support for the node discard attributes which sega rally2 uses to throw away specific geometry. This fixes junk that starts to show up in the levels after multiple runs.
Polygons have a line of sight value that's either a 0 or 1. We write this value into the stencil buffer, then read the app can read it back to determine the polygon attribute is visible or not. The returned value is 1/depth value in world coordinates. The first bit of the float is actually a control bit, 1 indicates no geometry hit, 0 indicates geometry hit.
We're not blending between LODs yet as we're not sure of the best way to implement it
Also implementing control bits for disable culling and enable model scale (needed for ECA and Harley)
Rewrite the scroll fog shader slightly. Scroll fog is a 2d layer, it has no depth, or can be considered to be drawn at infinity, therefore is not effected by the viewport light. The scroll attenatuion value also I think attenatutes the scroll fog alpha value. This fixes various effects in emergency call ambulance.
For a long time we've had bug reports that in vf3 the background in the Dural levels was the wrong colour, it should have been much darker. We thought it was again missing scroll fog, but gm_mathew worked out it was actually coming from the fogAmbient paramater. Not only does it darken the fog, but it also has an effect on the 2d background from the tilegen, similar to scroll fog. This also fixes the sky in lemans24.
Some games update the tilegen after the ping_ping bit has flipped at 66% of the frame, so we need to split the tilegen drawing up into two stages to get some effects to work. So having the tilegen draw independantly of the 3d chip can make this happen.
Tilegen shaders are mapped to uniforms, and the vram and palette are mapped to two textures.
TODO rip out the redundant code in the tilegen class. We don't need to pre-calculate palettes anymore. etc
The tilegen code supports has a start/end line so we can emulate as many lines as we want in a chunk, which will come in later as some games update the tilegen immediately after the ping_pong bit has flipped ~ 66% of the frame.
The scud rolling start tilegen bug is probably actually a bug in the original h/w implementation, that ends up looking correct on original h/w but not for us. Need hardware testing to confirm what it's actually doing.
