Compute implicit derivatives relative to first quad pixel.
Previously the derivatives in y were computed using the difference
between the second and fourth pixel in the quad. For consistency with
the x derivative, use the first and third pixel instead. Also, some
shuffling can be eliminated by having the x derivative in the y
component, and the y derivative in the z component.
Change-Id: I985dcd3c5e2c47c10caf020cf5cb79587b3b3aab
Reviewed-on: https://swiftshader-review.googlesource.com/14168
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
diff --git a/src/Shader/SamplerCore.cpp b/src/Shader/SamplerCore.cpp
index 0c86815..d0e420a 100644
--- a/src/Shader/SamplerCore.cpp
+++ b/src/Shader/SamplerCore.cpp
@@ -1421,7 +1421,7 @@
{
Float4 duvdxy;
- if(function != Grad)
+ if(function != Grad) // Implicit
{
duvdxy = Float4(uuuu.yz, vvvv.yz) - Float4(uuuu.xx, vvvv.xx);
}
@@ -1492,15 +1492,15 @@
{
Float4 dudxy, dvdxy, dsdxy;
- if(function != Grad)
+ if(function != Grad) // Implicit
{
Float4 U = u * M;
Float4 V = v * M;
Float4 W = w * M;
- dudxy = U.ywyw - U;
- dvdxy = V.ywyw - V;
- dsdxy = W.ywyw - W;
+ dudxy = U - U.xxxx;
+ dvdxy = V - V.xxxx;
+ dsdxy = W - W.xxxx;
}
else
{
@@ -1508,10 +1508,6 @@
dvdxy = Float4(dsx.y.xx, dsy.y.xx);
dsdxy = Float4(dsx.z.xx, dsy.z.xx);
- dudxy = Float4(dudxy.xz, dudxy.xz);
- dvdxy = Float4(dvdxy.xz, dvdxy.xz);
- dsdxy = Float4(dsdxy.xz, dsdxy.xz);
-
dudxy *= Float4(M.x);
dvdxy *= Float4(M.x);
dsdxy *= Float4(M.x);
@@ -1529,7 +1525,7 @@
dudxy += dvdxy;
dudxy += dsdxy;
- lod = Max(Float(dudxy.x), Float(dudxy.y)); // FIXME: Max(dudxy.x, dudxy.y);
+ lod = Max(Float(dudxy.y), Float(dudxy.z)); // FIXME: Max(dudxy.y, dudxy.z);
lod = log2sqrt(lod); // log2(sqrt(lod))
@@ -1568,21 +1564,17 @@
{
Float4 dudxy, dvdxy, dsdxy;
- if(function != Grad)
+ if(function != Grad) // Implicit
{
- dudxy = uuuu.ywyw - uuuu;
- dvdxy = vvvv.ywyw - vvvv;
- dsdxy = wwww.ywyw - wwww;
+ dudxy = uuuu - uuuu.xxxx;
+ dvdxy = vvvv - vvvv.xxxx;
+ dsdxy = wwww - wwww.xxxx;
}
else
{
dudxy = Float4(dsx.x.xx, dsy.x.xx);
dvdxy = Float4(dsx.y.xx, dsy.y.xx);
dsdxy = Float4(dsx.z.xx, dsy.z.xx);
-
- dudxy = Float4(dudxy.xz, dudxy.xz);
- dvdxy = Float4(dvdxy.xz, dvdxy.xz);
- dsdxy = Float4(dsdxy.xz, dsdxy.xz);
}
// Scale by texture dimensions and LOD
@@ -1597,7 +1589,7 @@
dudxy += dvdxy;
dudxy += dsdxy;
- lod = Max(Float(dudxy.x), Float(dudxy.y)); // FIXME: Max(dudxy.x, dudxy.y);
+ lod = Max(Float(dudxy.y), Float(dudxy.z)); // FIXME: Max(dudxy.y, dudxy.z);
lod = log2sqrt(lod); // log2(sqrt(lod))
