Specialize 1D sampling LOD calculation
Instead of reusing the 2D mipmap LOD calculation, this change adds a
separate method for computing the LOD for 1D sampling operations.
This also revealed that we would perform the anisotropic filtering
calculations on 1D sampling operations if enabled, which makes no sense.
This change limits it to 2D sampling only.
Bug: b/134669567
Change-Id: I05dd3fe358eccfcd01ebcff35872f56c6f0b0b70
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/47488
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Kokoro-Result: kokoro <noreply+kokoro@google.com>
diff --git a/src/Pipeline/SamplerCore.cpp b/src/Pipeline/SamplerCore.cpp
index 7410af1..6336730 100644
--- a/src/Pipeline/SamplerCore.cpp
+++ b/src/Pipeline/SamplerCore.cpp
@@ -63,16 +63,17 @@
if(function == Implicit || function == Bias || function == Grad || function == Query)
{
- if(state.textureType != VK_IMAGE_VIEW_TYPE_3D)
+ if(state.addressingModeV == ADDRESSING_UNUSED)
{
- if(!isCube())
- {
- computeLod(texture, lod, anisotropy, uDelta, vDelta, u, v, dsx, dsy, function);
- }
- else
- {
- computeLodCube(texture, lod, uvwa[0], uvwa[1], uvwa[2], dsx, dsy, M, function);
- }
+ computeLod1D(texture, lod, u, dsx, dsy, function);
+ }
+ else if(state.addressingModeW == ADDRESSING_UNUSED)
+ {
+ computeLod2D(texture, lod, anisotropy, uDelta, vDelta, u, v, dsx, dsy, function);
+ }
+ else if(isCube())
+ {
+ computeLodCube(texture, lod, uvwa[0], uvwa[1], uvwa[2], dsx, dsy, M, function);
}
else
{
@@ -423,7 +424,7 @@
{
Vector4s c;
- if(state.textureFilter != FILTER_ANISOTROPIC || function == Lod || function == Fetch)
+ if(state.textureFilter != FILTER_ANISOTROPIC)
{
c = sampleQuad(texture, u, v, w, a, offset, sample, lod, secondLOD, function);
}
@@ -895,7 +896,7 @@
{
Vector4f c;
- if(state.textureFilter != FILTER_ANISOTROPIC || function == Lod || function == Fetch)
+ if(state.textureFilter != FILTER_ANISOTROPIC)
{
c = sampleFloat(texture, u, v, w, a, dRef, offset, sample, lod, secondLOD, function);
}
@@ -1137,9 +1138,9 @@
return c;
}
-Float SamplerCore::log2sqrt(Float lod)
+static Float log2sqrt(Float lod)
{
- // log2(sqrt(lod)) // Equals 0.25 * log2(lod^2).
+ // log2(sqrt(lod)) // Equals 0.25 * log2(lod^2).
lod *= lod; // Squaring doubles the exponent and produces an extra bit of precision.
lod = Float(As<Int>(lod)) - Float(0x3F800000); // Interpret as integer and subtract the exponent bias.
lod *= As<Float>(Int(0x33000000)); // Scale by 0.25 * 2^-23 (mantissa length).
@@ -1147,7 +1148,7 @@
return lod;
}
-Float SamplerCore::log2(Float lod)
+static Float log2(Float lod)
{
lod *= lod; // Squaring doubles the exponent and produces an extra bit of precision.
lod = Float(As<Int>(lod)) - Float(0x3F800000); // Interpret as integer and subtract the exponent bias.
@@ -1156,7 +1157,31 @@
return lod;
}
-void SamplerCore::computeLod(Pointer<Byte> &texture, Float &lod, Float &anisotropy, Float4 &uDelta, Float4 &vDelta, Float4 &uuuu, Float4 &vvvv, Float4 &dsx, Float4 &dsy, SamplerFunction function)
+void SamplerCore::computeLod1D(Pointer<Byte> &texture, Float &lod, Float4 &uuuu, Float4 &dsx, Float4 &dsy, SamplerFunction function)
+{
+ Float4 dudxy;
+
+ if(function != Grad) // Implicit
+ {
+ dudxy = uuuu.yz - uuuu.xx;
+ }
+ else
+ {
+ dudxy = UnpackLow(dsx, dsy);
+ }
+
+ // Scale by texture dimensions.
+ Float4 dUdxy = dudxy * *Pointer<Float4>(texture + OFFSET(Texture, widthWidthHeightHeight));
+
+ // Note we could take the absolute value here and omit the square root below,
+ // but this is more consistent with the 2D calculation and still cheap.
+ Float4 dU2dxy = dUdxy * dUdxy;
+
+ lod = Max(Float(dU2dxy.x), Float(dU2dxy.y));
+ lod = log2sqrt(lod);
+}
+
+void SamplerCore::computeLod2D(Pointer<Byte> &texture, Float &lod, Float &anisotropy, Float4 &uDelta, Float4 &vDelta, Float4 &uuuu, Float4 &vvvv, Float4 &dsx, Float4 &dsy, SamplerFunction function)
{
Float4 duvdxy;
