Fix integer texture sampling with explicit gradients
The lod level should be selected according to the explicit gradients,
and the gradients are relative to the normalized texture coordinates,
so they need to be multiplied by the base level dimensions to get the
correct gradients to use in the lod level formula.
In the case of sampling integer cube maps, the derivatives of the
texture coordinates on the cube map face need to be calculated based
on the derivatives of the cube map direction vector components.
Also includes fix for sampling integer cube maps with explicit LOD.
BUG=angleproject:1092
TEST=dEQP-GLES3.functional.shaders.texture_functions.*grad*
Change-Id: Iadd358e713fa9695e755e98db8f368e8c512ac45
Reviewed-on: https://chromium-review.googlesource.com/337100
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
diff --git a/src/compiler/translator/OutputHLSL.cpp b/src/compiler/translator/OutputHLSL.cpp
index 231b0f7..a5c9d2a 100644
--- a/src/compiler/translator/OutputHLSL.cpp
+++ b/src/compiler/translator/OutputHLSL.cpp
@@ -968,13 +968,53 @@
out << " t.y = (v * 0.5f / m) + 0.5f;\n";
// Mip level computation.
- if (textureFunction->method == TextureFunction::IMPLICIT)
+ if (textureFunction->method == TextureFunction::IMPLICIT ||
+ textureFunction->method == TextureFunction::LOD ||
+ textureFunction->method == TextureFunction::GRAD)
{
- out << " float2 tSized = float2(t.x * width, t.y * height);\n"
- " float2 dx = ddx(tSized);\n"
- " float2 dy = ddy(tSized);\n"
- " float lod = 0.5f * log2(max(dot(dx, dx), dot(dy, dy)));\n"
- " mip = uint(min(max(round(lod), 0), levels - 1));\n"
+ if (textureFunction->method == TextureFunction::IMPLICIT)
+ {
+ out << " float2 tSized = float2(t.x * width, t.y * height);\n"
+ " float2 dx = ddx(tSized);\n"
+ " float2 dy = ddy(tSized);\n"
+ " float lod = 0.5f * log2(max(dot(dx, dx), dot(dy, dy)));\n";
+ }
+ else if (textureFunction->method == TextureFunction::GRAD)
+ {
+ // ESSL 3.00.6 spec section 8.8: "For the cube version, the partial
+ // derivatives of P are assumed to be in the coordinate system used before
+ // texture coordinates are projected onto the appropriate cube face."
+ // ddx[0] and ddy[0] are the derivatives of t.x passed into the function
+ // ddx[1] and ddy[1] are the derivatives of t.y passed into the function
+ // ddx[2] and ddy[2] are the derivatives of t.z passed into the function
+ // Determine the derivatives of u, v and m
+ out << " float dudx = xMajor ? ddx[2] : (yMajor && t.y < 0.0f ? -ddx[0] "
+ ": ddx[0]);\n"
+ " float dudy = xMajor ? ddy[2] : (yMajor && t.y < 0.0f ? -ddy[0] "
+ ": ddy[0]);\n"
+ " float dvdx = yMajor ? ddx[2] : (negative ? ddx[1] : -ddx[1]);\n"
+ " float dvdy = yMajor ? ddy[2] : (negative ? ddy[1] : -ddy[1]);\n"
+ " float dmdx = xMajor ? ddx[0] : (yMajor ? ddx[1] : ddx[2]);\n"
+ " float dmdy = xMajor ? ddy[0] : (yMajor ? ddy[1] : ddy[2]);\n";
+ // Now determine the derivatives of the face coordinates, using the
+ // derivatives calculated above.
+ // d / dx (u(x) * 0.5 / m(x) + 0.5)
+ // = 0.5 * (m(x) * u'(x) - u(x) * m'(x)) / m(x)^2
+ out << " float dfacexdx = 0.5f * (m * dudx - u * dmdx) / (m * m);\n"
+ " float dfaceydx = 0.5f * (m * dvdx - v * dmdx) / (m * m);\n"
+ " float dfacexdy = 0.5f * (m * dudy - u * dmdy) / (m * m);\n"
+ " float dfaceydy = 0.5f * (m * dvdy - v * dmdy) / (m * m);\n"
+ " float2 sizeVec = float2(width, height);\n"
+ " float2 faceddx = float2(dfacexdx, dfaceydx) * sizeVec;\n"
+ " float2 faceddy = float2(dfacexdy, dfaceydy) * sizeVec;\n";
+ // Optimization: instead of: log2(max(length(faceddx), length(faceddy)))
+ // we compute: log2(max(length(faceddx)^2, length(faceddy)^2)) / 2
+ out << " float lengthfaceddx2 = dot(faceddx, faceddx);\n"
+ " float lengthfaceddy2 = dot(faceddy, faceddy);\n"
+ " float lod = log2(max(lengthfaceddx2, lengthfaceddy2)) * "
+ "0.5f;\n";
+ }
+ out << " mip = uint(min(max(round(lod), 0), levels - 1));\n"
<< " " << textureReference
<< ".GetDimensions(mip, width, height, layers, levels);\n";
}
@@ -1021,7 +1061,11 @@
}
else if (textureFunction->method == TextureFunction::GRAD)
{
- out << " float lod = log2(max(length(ddx), length(ddy)));\n";
+ out << " float2 sizeVec = float2(width, height);\n"
+ " float2 sizeDdx = ddx * sizeVec;\n"
+ " float2 sizeDdy = ddy * sizeVec;\n"
+ " float lod = log2(max(dot(sizeDdx, sizeDdx), "
+ "dot(sizeDdy, sizeDdy))) * 0.5f;\n";
}
out << " uint mip = uint(min(max(round(lod), 0), levels - 1));\n";
@@ -1062,7 +1106,11 @@
}
else if (textureFunction->method == TextureFunction::GRAD)
{
- out << " float lod = log2(max(length(ddx), length(ddy)));\n";
+ out << " float2 sizeVec = float2(width, height);\n"
+ " float2 sizeDdx = ddx * sizeVec;\n"
+ " float2 sizeDdy = ddy * sizeVec;\n"
+ " float lod = log2(max(dot(sizeDdx, sizeDdx), "
+ "dot(sizeDdy, sizeDdy))) * 0.5f;\n";
}
out << " uint mip = uint(min(max(round(lod), 0), levels - 1));\n";
@@ -1105,7 +1153,11 @@
}
else if (textureFunction->method == TextureFunction::GRAD)
{
- out << " float lod = log2(max(length(ddx), length(ddy)));\n";
+ out << " float3 sizeVec = float3(width, height, depth);\n"
+ " float3 sizeDdx = ddx * sizeVec;\n"
+ " float3 sizeDdy = ddy * sizeVec;\n"
+ " float lod = log2(max(dot(sizeDdx, sizeDdx), dot(sizeDdy, "
+ "sizeDdy))) * 0.5f;\n";
}
out << " uint mip = uint(min(max(round(lod), 0), levels - 1));\n";