Separate user and raw stencil settings

src/gpu/GrStencilSettings.cpp

+/*
+ * Copyright 2011 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#include "GrStencilSettings.h"
+
+#include "GrProcessor.h"
+
+constexpr const GrUserStencilSettings gUnused(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kAlwaysIfInClip,
+        0xffff,
+        GrUserStencilOp::kKeep,
+        GrUserStencilOp::kKeep,
+        0x0000>()
+);
+
+GR_STATIC_ASSERT(kAll_StencilFlags == (gUnused.fFrontFlags[0] & gUnused.fBackFlags[0]));
+
+const GrUserStencilSettings& GrUserStencilSettings::kUnused = gUnused;
+
+void GrStencilSettings::reset(const GrUserStencilSettings& user, bool hasStencilClip,
+                              int numStencilBits) {
+    uint16_t frontFlags = user.fFrontFlags[hasStencilClip];
+    if (frontFlags & kSingleSided_StencilFlag) {
+        fFlags = frontFlags;
+        if (!this->isDisabled()) {
+            fFront.reset(user.fFront, hasStencilClip, numStencilBits);
+        }
+        return;
+    }
+
+    uint16_t backFlags = user.fBackFlags[hasStencilClip];
+    fFlags = frontFlags & backFlags;
+    if (this->isDisabled()) {
+        return;
+    }
+    if (!(frontFlags & kDisabled_StencilFlag)) {
+        fFront.reset(user.fFront, hasStencilClip, numStencilBits);
+    } else {
+        fFront.setDisabled();
+    }
+    if (!(backFlags & kDisabled_StencilFlag)) {
+        fBack.reset(user.fBack, hasStencilClip, numStencilBits);
+    } else {
+        fBack.setDisabled();
+    }
+}
+
+void GrStencilSettings::reset(const GrStencilSettings& that) {
+    fFlags = that.fFlags;
+    if ((kInvalid_PrivateFlag | kDisabled_StencilFlag) & fFlags) {
+        return;
+    }
+    if (!this->isTwoSided()) {
+        memcpy(&fFront, &that.fFront, sizeof(Face));
+    } else {
+        memcpy(&fFront, &that.fFront, 2 * sizeof(Face));
+        GR_STATIC_ASSERT(sizeof(Face) ==
+                         offsetof(GrStencilSettings, fBack) - offsetof(GrStencilSettings, fFront));
+    }
+}
+
+bool GrStencilSettings::operator==(const GrStencilSettings& that) const {
+    if ((kInvalid_PrivateFlag | kDisabled_StencilFlag) & (fFlags | that.fFlags)) {
+        // At least one is invalid and/or disabled.
+        if (kInvalid_PrivateFlag & (fFlags | that.fFlags)) {
+            return false; // We never allow invalid stencils to be equal.
+        }
+        // They're only equal if both are disabled.
+        return kDisabled_StencilFlag & (fFlags & that.fFlags);
+    }
+    if (kSingleSided_StencilFlag & (fFlags & that.fFlags)) {
+        return 0 == memcmp(&fFront, &that.fFront, sizeof(Face)); // Both are single sided.
+    } else {
+        return 0 == memcmp(&fFront, &that.fFront, 2 * sizeof(Face));
+        GR_STATIC_ASSERT(sizeof(Face) ==
+                         offsetof(GrStencilSettings, fBack) - offsetof(GrStencilSettings, fFront));
+    }
+    // memcmp relies on GrStencilSettings::Face being tightly packed.
+    GR_STATIC_ASSERT(0 == offsetof(Face, fRef));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fRef));
+    GR_STATIC_ASSERT(2 == offsetof(Face, fTest));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fTest));
+    GR_STATIC_ASSERT(4 == offsetof(Face, fTestMask));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fTestMask));
+    GR_STATIC_ASSERT(6 == offsetof(Face, fPassOp));
+    GR_STATIC_ASSERT(1 == sizeof(Face::fPassOp));
+    GR_STATIC_ASSERT(7 == offsetof(Face, fFailOp));
+    GR_STATIC_ASSERT(1 == sizeof(Face::fFailOp));
+    GR_STATIC_ASSERT(8 == offsetof(Face, fWriteMask));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fWriteMask));
+    GR_STATIC_ASSERT(10 == sizeof(Face));
+}
+
+static constexpr GrStencilTest gUserStencilTestToRaw[kGrUserStencilTestCount] = {
+    // Tests that respect the clip.
+    GrStencilTest::kAlways,  // kAlwaysIfInClip (This is only for when there is not a stencil clip).
+    GrStencilTest::kEqual,   // kEqualIfInClip.
+    GrStencilTest::kLess,    // kLessIfInClip.
+    GrStencilTest::kLEqual,  // kLEqualIfInClip.
+
+    // Tests that ignore the clip.
+    GrStencilTest::kAlways,
+    GrStencilTest::kNever,
+    GrStencilTest::kGreater,
+    GrStencilTest::kGEqual,
+    GrStencilTest::kLess,
+    GrStencilTest::kLEqual,
+    GrStencilTest::kEqual,
+    GrStencilTest::kNotEqual
+};
+
+GR_STATIC_ASSERT(0 == (int)GrUserStencilTest::kAlwaysIfInClip);
+GR_STATIC_ASSERT(1 == (int)GrUserStencilTest::kEqualIfInClip);
+GR_STATIC_ASSERT(2 == (int)GrUserStencilTest::kLessIfInClip);
+GR_STATIC_ASSERT(3 == (int)GrUserStencilTest::kLEqualIfInClip);
+GR_STATIC_ASSERT(4 == (int)GrUserStencilTest::kAlways);
+GR_STATIC_ASSERT(5 == (int)GrUserStencilTest::kNever);
+GR_STATIC_ASSERT(6 == (int)GrUserStencilTest::kGreater);
+GR_STATIC_ASSERT(7 == (int)GrUserStencilTest::kGEqual);
+GR_STATIC_ASSERT(8 == (int)GrUserStencilTest::kLess);
+GR_STATIC_ASSERT(9 == (int)GrUserStencilTest::kLEqual);
+GR_STATIC_ASSERT(10 == (int)GrUserStencilTest::kEqual);
+GR_STATIC_ASSERT(11 == (int)GrUserStencilTest::kNotEqual);
+
+static constexpr GrStencilOp gUserStencilOpToRaw[kGrUserStencilOpCount] = {
+    GrStencilOp::kKeep,
+
+    // Ops that only modify user bits.
+    GrStencilOp::kZero,
+    GrStencilOp::kReplace,
+    GrStencilOp::kInvert,
+    GrStencilOp::kIncWrap,
+    GrStencilOp::kDecWrap,
+    GrStencilOp::kIncClamp,  // kIncMaybeClamp.
+    GrStencilOp::kDecClamp,  // kDecMaybeClamp.
+
+    // Ops that only modify the clip bit.
+    GrStencilOp::kZero,      // kZeroClipBit.
+    GrStencilOp::kReplace,   // kSetClipBit.
+    GrStencilOp::kInvert,    // kInvertClipBit.
+
+    // Ops that modify clip and user bits.
+    GrStencilOp::kReplace,   // kSetClipAndReplaceUserBits.
+    GrStencilOp::kZero       // kZeroClipAndUserBits.
+};
+
+GR_STATIC_ASSERT(0 == (int)GrUserStencilOp::kKeep);
+GR_STATIC_ASSERT(1 == (int)GrUserStencilOp::kZero);
+GR_STATIC_ASSERT(2 == (int)GrUserStencilOp::kReplace);
+GR_STATIC_ASSERT(3 == (int)GrUserStencilOp::kInvert);
+GR_STATIC_ASSERT(4 == (int)GrUserStencilOp::kIncWrap);
+GR_STATIC_ASSERT(5 == (int)GrUserStencilOp::kDecWrap);
+GR_STATIC_ASSERT(6 == (int)GrUserStencilOp::kIncMaybeClamp);
+GR_STATIC_ASSERT(7 == (int)GrUserStencilOp::kDecMaybeClamp);
+GR_STATIC_ASSERT(8 == (int)GrUserStencilOp::kZeroClipBit);
+GR_STATIC_ASSERT(9 == (int)GrUserStencilOp::kSetClipBit);
+GR_STATIC_ASSERT(10 == (int)GrUserStencilOp::kInvertClipBit);
+GR_STATIC_ASSERT(11 == (int)GrUserStencilOp::kSetClipAndReplaceUserBits);
+GR_STATIC_ASSERT(12 == (int)GrUserStencilOp::kZeroClipAndUserBits);
+
+void GrStencilSettings::Face::reset(const GrUserStencilSettings::Face& user, bool hasStencilClip,
+                                    int numStencilBits) {
+    SkASSERT(user.fTest < (GrUserStencilTest)kGrUserStencilTestCount);
+    SkASSERT(user.fPassOp < (GrUserStencilOp)kGrUserStencilOpCount);
+    SkASSERT(user.fFailOp < (GrUserStencilOp)kGrUserStencilOpCount);
+    SkASSERT(numStencilBits <= 16);
+    int clipBit = 1 << (numStencilBits - 1);
+    int userMask = clipBit - 1;
+
+    GrUserStencilOp maxOp = SkTMax(user.fPassOp, user.fFailOp);
+    SkDEBUGCODE(GrUserStencilOp otherOp = SkTMin(user.fPassOp, user.fFailOp);)
+    if (maxOp <= kLastUserOnlyStencilOp) {
+        // Ops that only modify user bits.
+        fWriteMask = user.fWriteMask & userMask;
+        SkASSERT(otherOp <= kLastUserOnlyStencilOp);
+    } else if (maxOp <= kLastClipOnlyStencilOp) {
+        // Ops that only modify the clip bit.
+        fWriteMask = clipBit;
+        SkASSERT(GrUserStencilOp::kKeep == otherOp ||
+                 (otherOp > kLastUserOnlyStencilOp && otherOp <= kLastClipOnlyStencilOp));
+    } else {
+        // Ops that modify both clip and user bits.
+        fWriteMask = clipBit | (user.fWriteMask & userMask);
+        SkASSERT(GrUserStencilOp::kKeep == otherOp || otherOp > kLastClipOnlyStencilOp);
+    }
+
+    fFailOp = gUserStencilOpToRaw[(int)user.fFailOp];
+    fPassOp = gUserStencilOpToRaw[(int)user.fPassOp];
+
+    if (!hasStencilClip || user.fTest > kLastClippedStencilTest) {
+        // Ignore the clip.
+        fTestMask = user.fTestMask & userMask;
+        fTest = gUserStencilTestToRaw[(int)user.fTest];
+    } else if (GrUserStencilTest::kAlwaysIfInClip != user.fTest) {
+        // Respect the clip.
+        fTestMask = clipBit | (user.fTestMask & userMask);
+        fTest = gUserStencilTestToRaw[(int)user.fTest];
+    } else {
+        // Test only for clip.
+        fTestMask = clipBit;
+        fTest = GrStencilTest::kEqual;
+    }
+
+    fRef = (clipBit | user.fRef) & (fTestMask | fWriteMask);
+}
+
+void GrStencilSettings::Face::setDisabled() {
+    memset(this, 0, sizeof(*this));
+    GR_STATIC_ASSERT(0 == (int)GrStencilTest::kAlways);
+    GR_STATIC_ASSERT(0 == (int)GrStencilOp::kKeep);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Stencil Rules for Merging user stencil space into clip
+//
+
+///////
+// Replace
+static constexpr GrUserStencilSettings gUserToClipReplace(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kNotEqual,
+        0xffff,
+        GrUserStencilOp::kSetClipAndReplaceUserBits,
+        GrUserStencilOp::kZeroClipAndUserBits,
+        0xffff>()
+);
+
+static constexpr GrUserStencilSettings gInvUserToClipReplace(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kEqual,
+        0xffff,
+        GrUserStencilOp::kSetClipAndReplaceUserBits,
+        GrUserStencilOp::kZeroClipAndUserBits,
+        0xffff>()
+);
+
+///////
+// Intersect
+static constexpr GrUserStencilSettings gUserToClipIsect(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kLessIfInClip, // "0 < userBits" is equivalent to "0 != userBits".
+        0xffff,
+        GrUserStencilOp::kSetClipAndReplaceUserBits,
+        GrUserStencilOp::kZeroClipAndUserBits,
+        0xffff>()
+);
+
+///////
+// Difference
+static constexpr GrUserStencilSettings gUserToClipDiff(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kEqualIfInClip,
+        0xffff,
+        GrUserStencilOp::kSetClipAndReplaceUserBits,
+        GrUserStencilOp::kZeroClipAndUserBits,
+        0xffff>()
+);
+
+///////
+// Union
+static constexpr GrUserStencilSettings gUserToClipUnion(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kNotEqual,
+        0xffff,
+        GrUserStencilOp::kSetClipAndReplaceUserBits,
+        GrUserStencilOp::kKeep,
+        0xffff>()
+);
+
+static constexpr GrUserStencilSettings gInvUserToClipUnionPass0( // Does not zero user bits.
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kEqual,
+        0xffff,
+        GrUserStencilOp::kSetClipBit,
+        GrUserStencilOp::kKeep,
+        0x0000>()
+);
+
+///////
+// Xor
+static constexpr GrUserStencilSettings gUserToClipXorPass0( // Does not zero user bits.
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kNotEqual,
+        0xffff,
+        GrUserStencilOp::kInvertClipBit,
+        GrUserStencilOp::kKeep,
+        0x0000>()
+);
+
+static constexpr GrUserStencilSettings gInvUserToClipXorPass0( // Does not zero user bits.
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kEqual,
+        0xffff,
+        GrUserStencilOp::kInvertClipBit,
+        GrUserStencilOp::kKeep,
+        0x0000>()
+);
+
+///////
+// Reverse Diff
+static constexpr GrUserStencilSettings gUserToClipRDiffPass0( // Does not zero user bits.
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kNotEqual,
+        0xffff,
+        GrUserStencilOp::kInvertClipBit,
+        GrUserStencilOp::kZeroClipBit,
+        0x0000>()
+);
+
+static constexpr GrUserStencilSettings gInvUserToClipRDiffPass0( // Does not zero user bits.
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kEqual,
+        0xffff,
+        GrUserStencilOp::kInvertClipBit,
+        GrUserStencilOp::kZeroClipBit,
+        0x0000>()
+);
+
+///////
+// Second pass to clear user bits (only needed sometimes)
+static constexpr GrUserStencilSettings gZeroUserBits(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kNotEqual,
+        0xffff,
+        GrUserStencilOp::kZero,
+        GrUserStencilOp::kKeep,
+        0xffff>()
+);
+
+static constexpr const GrUserStencilSettings* gUserToClipTable[2][1 + SkRegion::kLastOp][3] = {
+    {  /* Normal fill. */
+        {&gUserToClipDiff,           nullptr,         nullptr},  // kDifference_Op.
+        {&gUserToClipIsect,          nullptr,         nullptr},  // kIntersect_Op.
+        {&gUserToClipUnion,          nullptr,         nullptr},  // kUnion_Op.
+        {&gUserToClipXorPass0,       &gZeroUserBits,  nullptr},  // kXOR_Op.
+        {&gUserToClipRDiffPass0,     &gZeroUserBits,  nullptr},  // kReverseDifference_Op.
+        {&gUserToClipReplace,        nullptr,         nullptr}   // kReplace_Op.
+
+    }, /* Inverse fill. */ {
+        {&gUserToClipIsect,          nullptr,         nullptr},  // ~diff (aka isect).
+        {&gUserToClipDiff,           nullptr,         nullptr},  // ~isect (aka diff).
+        {&gInvUserToClipUnionPass0,  &gZeroUserBits,  nullptr},  // ~union.
+        {&gInvUserToClipXorPass0,    &gZeroUserBits,  nullptr},  // ~xor.
+        {&gInvUserToClipRDiffPass0,  &gZeroUserBits,  nullptr},  // ~reverse diff.
+        {&gInvUserToClipReplace,     nullptr,         nullptr}   // ~replace.
+    }
+};
+
+GR_STATIC_ASSERT(0 == SkRegion::kDifference_Op);
+GR_STATIC_ASSERT(1 == SkRegion::kIntersect_Op);
+GR_STATIC_ASSERT(2 == SkRegion::kUnion_Op);
+GR_STATIC_ASSERT(3 == SkRegion::kXOR_Op);
+GR_STATIC_ASSERT(4 == SkRegion::kReverseDifference_Op);
+GR_STATIC_ASSERT(5 == SkRegion::kReplace_Op);
+
+///////
+// Direct to Stencil
+
+// We can render a clip element directly without first writing to the client
+// portion of the clip when the fill is not inverse and the set operation will
+// only modify the in/out status of samples covered by the clip element.
+
+// this one only works if used right after stencil clip was cleared.
+// Our clip mask creation code doesn't allow midstream replace ops.
+static constexpr GrUserStencilSettings gReplaceClip(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kAlways,
+        0xffff,
+        GrUserStencilOp::kSetClipBit,
+        GrUserStencilOp::kSetClipBit,
+        0x0000>()
+);
+
+static constexpr GrUserStencilSettings gUnionClip(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kAlwaysIfInClip,
+        0xffff,
+        GrUserStencilOp::kKeep,
+        GrUserStencilOp::kSetClipBit,
+        0x0000>()
+);
+
+static constexpr GrUserStencilSettings gXorClip(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kAlways,
+        0xffff,
+        GrUserStencilOp::kInvertClipBit,
+        GrUserStencilOp::kInvertClipBit,
+        0x0000>()
+);
+
+static constexpr GrUserStencilSettings gDiffClip(
+    GrUserStencilSettings::StaticInit<
+        0x0000,
+        GrUserStencilTest::kAlwaysIfInClip,
+        0xffff,
+        GrUserStencilOp::kZeroClipBit,
+        GrUserStencilOp::kKeep,
+        0x0000>()
+);
+
+static constexpr const GrUserStencilSettings* gDirectDrawTable[1 + SkRegion::kLastOp][2] = {
+    {&gDiffClip,     nullptr},  // kDifference_Op.
+    {nullptr,        nullptr},  // kIntersect_Op.
+    {&gUnionClip,    nullptr},  // kUnion_Op.
+    {&gXorClip,      nullptr},  // kXOR_Op.
+    {nullptr,        nullptr},  // kReverseDifference_Op.
+    {&gReplaceClip,  nullptr}   // kReplace_Op.
+};
+
+GR_STATIC_ASSERT(0 == SkRegion::kDifference_Op);
+GR_STATIC_ASSERT(1 == SkRegion::kIntersect_Op);
+GR_STATIC_ASSERT(2 == SkRegion::kUnion_Op);
+GR_STATIC_ASSERT(3 == SkRegion::kXOR_Op);
+GR_STATIC_ASSERT(4 == SkRegion::kReverseDifference_Op);
+GR_STATIC_ASSERT(5 == SkRegion::kReplace_Op);
+
+GrUserStencilSettings const* const* GrStencilSettings::GetClipPasses(SkRegion::Op op,
+                                                                     bool canBeDirect,
+                                                                     bool invertedFill,
+                                                                     bool* drawDirectToClip) {
+    SkASSERT((unsigned)op <= SkRegion::kLastOp);
+    if (canBeDirect && !invertedFill) { // TODO: inverse fill + intersect op can be direct.
+        GrUserStencilSettings const* const* directPass = gDirectDrawTable[op];
+        if (directPass[0]) {
+            *drawDirectToClip = true;
+            return directPass;
+        }
+    }
+    *drawDirectToClip = false;
+    return gUserToClipTable[invertedFill][op];
+}
+
+void GrStencilSettings::genKey(GrProcessorKeyBuilder* b) const {
+    b->add32(fFlags);
+    if (this->isDisabled()) {
+        return;
+    }
+    if (!this->isTwoSided()) {
+        constexpr int kCount16 = sizeof(Face) / sizeof(uint16_t);
+        GR_STATIC_ASSERT(0 == sizeof(Face) % sizeof(uint16_t));
+        uint16_t* key = reinterpret_cast<uint16_t*>(b->add32n((kCount16 + 1) / 2));
+        memcpy(key, &fFront, sizeof(Face));
+        key[kCount16] = 0;
+        GR_STATIC_ASSERT(1 == kCount16 % 2);
+    } else {
+        constexpr int kCount32 = (2 * sizeof(Face)) / sizeof(uint32_t);
+        GR_STATIC_ASSERT(0 == (2 * sizeof(Face)) % sizeof(uint32_t));
+        uint32_t* key = b->add32n(kCount32);
+        memcpy(key, &fFront, 2 * sizeof(Face));
+        GR_STATIC_ASSERT(sizeof(Face) ==
+                         offsetof(GrStencilSettings, fBack) - offsetof(GrStencilSettings, fFront));
+    }
+    // We rely on GrStencilSettings::Face being tightly packed for the key to be reliable.
+    GR_STATIC_ASSERT(0 == offsetof(Face, fRef));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fRef));
+    GR_STATIC_ASSERT(2 == offsetof(Face, fTest));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fTest));
+    GR_STATIC_ASSERT(4 == offsetof(Face, fTestMask));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fTestMask));
+    GR_STATIC_ASSERT(6 == offsetof(Face, fPassOp));
+    GR_STATIC_ASSERT(1 == sizeof(Face::fPassOp));
+    GR_STATIC_ASSERT(7 == offsetof(Face, fFailOp));
+    GR_STATIC_ASSERT(1 == sizeof(Face::fFailOp));
+    GR_STATIC_ASSERT(8 == offsetof(Face, fWriteMask));
+    GR_STATIC_ASSERT(2 == sizeof(Face::fWriteMask));
+    GR_STATIC_ASSERT(10 == sizeof(Face));
+}