piwalker/melonDS
1
0
Fork 0
mirror of https://github.com/melonDS-emu/melonDS.git synced 2024-11-14 21:37:42 -07:00
Code Issues Actions Packages Projects Releases Wiki Activity

GPU3D: more accurate viewport transform (emulate quirk with W greater than 0xFFFF)

Browse Source
This commit is contained in:
Arisotura 2020-04-12 16:40:08 +02:00
parent 33b4cdb077
commit ec6e4a2d1e
1 changed files with 21 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
src/GPU3D.cpp
View File

@ -1181,8 +1181,11 @@ void SubmitPolygon()
vtx->Position[3] &= 0x00FFFFFF;
// viewport transform
s32 posX, posY;
s32 w = vtx->Position[3];
// note: the DS performs these divisions using a 32-bit divider
// thus, if W is greater than 0xFFFF, some precision is sacrificed
// to make the numbers fit into the divider
u32 posX, posY;
u32 w = vtx->Position[3];
if (w == 0)
{
posX = 0;
@ -1190,14 +1193,27 @@ void SubmitPolygon()
}
else
{
posX = (((s64)(vtx->Position[0] + w) * Viewport[4]) / (((s64)w) << 1)) + Viewport[0];
posY = (((s64)(-vtx->Position[1] + w) * Viewport[5]) / (((s64)w) << 1)) + Viewport[3];
posX = vtx->Position[0] + w;
posY = -vtx->Position[1] + w;
u32 den = w;
if (w > 0xFFFF)
{
posX >>= 1;
posY >>= 1;
den >>= 1;
}
den <<= 1;
posX = ((posX * Viewport[4]) / den) + Viewport[0];
posY = ((posY * Viewport[5]) / den) + Viewport[3];
}
vtx->FinalPosition[0] = posX & 0x1FF;
vtx->FinalPosition[1] = posY & 0xFF;
// hi-res positions
// to consider: only do this when using the GL renderer? apply the aforementioned quirk to this?
if (w != 0)
{
posX = ((((s64)(vtx->Position[0] + w) * Viewport[4]) << 4) / (((s64)w) << 1)) + (Viewport[0] << 4);
@ -1229,8 +1245,7 @@ void SubmitPolygon()
break;
}
s32 w = vtx->Position[3];
if (w <= ZeroDotWLimit)
if (vtx->Position[3] <= ZeroDotWLimit)
{
allbehind = false;
break;