skgpu::ganesh::QuadPerEdgeAA::Tessellator Class Reference

#include <QuadPerEdgeAA.h>

Public Member Functions
	Tessellator (const VertexSpec &spec, char *vertices)
void	append (GrQuad *deviceQuad, GrQuad *localQuad, const SkPMColor4f &color, const SkRect &uvSubset, GrQuadAAFlags aaFlags)

Static Public Member Functions
static SkDEBUGCODE(skgpu::BufferWriter::Mark vertexMark() const { return fVertexWriter.mark();}) private WriteQuadProc	GetWriteQuadProc (const VertexSpec &spec)

Public Attributes
GrQuadUtils::TessellationHelper	fAAHelper
VertexSpec	fVertexSpec
VertexWriter	fVertexWriter
WriteQuadProc	fWriteProc

Detailed Description

Definition at line 146 of file QuadPerEdgeAA.h.

Constructor & Destructor Documentation

Tessellator()

skgpu::ganesh::QuadPerEdgeAA::Tessellator::Tessellator ( const VertexSpec &  spec, char *  vertices  )

explicit

Definition at line 363 of file QuadPerEdgeAA.cpp.

        : fVertexSpec(spec)
        , fVertexWriter{vertices}
        , fWriteProc(Tessellator::GetWriteQuadProc(spec)) {}

Member Function Documentation

append()

void skgpu::ganesh::QuadPerEdgeAA::Tessellator::append	(	GrQuad *	deviceQuad,
		GrQuad *	localQuad,
		const SkPMColor4f &	color,
		const SkRect &	uvSubset,
		GrQuadAAFlags	aaFlags
	)

Definition at line 368 of file QuadPerEdgeAA.cpp.

                                                                                                  {
    // We allow Tessellator to be created with a null vertices pointer for convenience, but it is
    // assumed it will never actually be used in those cases.
    SkASSERT(fVertexWriter);
    SkASSERT(deviceQuad->quadType() <= fVertexSpec.deviceQuadType());
    SkASSERT(localQuad || !fVertexSpec.hasLocalCoords());
    SkASSERT(!fVertexSpec.hasLocalCoords() || localQuad->quadType() <= fVertexSpec.localQuadType());
 
    static const float kFullCoverage[4] = {1.f, 1.f, 1.f, 1.f};
    static const float kZeroCoverage[4] = {0.f, 0.f, 0.f, 0.f};
    static const SkRect kIgnoredSubset = SkRect::MakeEmpty();
 
    if (fVertexSpec.usesCoverageAA()) {
        SkASSERT(fVertexSpec.coverageMode() == CoverageMode::kWithColor ||
                 fVertexSpec.coverageMode() == CoverageMode::kWithPosition);
        // Must calculate inner and outer quadrilaterals for the vertex coverage ramps, and possibly
        // a geometry subset if corners are not right angles
        SkRect geomSubset;
        if (fVertexSpec.requiresGeometrySubset()) {
            // Our GP code expects a 0.5 outset rect (coverage is computed as 0 at the values of
            // the uniform). However, if we have quad edges that aren't supposed to be antialiased
            // they may lie close to the bounds. So in that case we outset by an additional 0.5.
            // This is a sort of backup clipping mechanism for cases where quad outsetting of nearly
            // parallel edges produces long thin extrusions from the original geometry.
            float outset = aaFlags == GrQuadAAFlags::kAll ? 0.5f : 1.f;
            geomSubset = deviceQuad->bounds().makeOutset(outset, outset);
        }
 
        if (aaFlags == GrQuadAAFlags::kNone) {
            // Have to write the coverage AA vertex structure, but there's no math to be done for a
            // non-aa quad batched into a coverage AA op.
            fWriteProc(&fVertexWriter, fVertexSpec, deviceQuad, localQuad, kFullCoverage, color,
                       geomSubset, uvSubset);
            // Since we pass the same corners in, the outer vertex structure will have 0 area and
            // the coverage interpolation from 1 to 0 will not be visible.
            fWriteProc(&fVertexWriter, fVertexSpec, deviceQuad, localQuad, kZeroCoverage, color,
                       geomSubset, uvSubset);
        } else {
            // Reset the tessellation helper to match the current geometry
            fAAHelper.reset(*deviceQuad, localQuad);
 
            // Edge inset/outset distance ordered LBTR, set to 0.5 for a half pixel if the AA flag
            // is turned on, or 0.0 if the edge is not anti-aliased.
            skvx::Vec<4, float> edgeDistances;
            if (aaFlags == GrQuadAAFlags::kAll) {
                edgeDistances = 0.5f;
            } else {
                edgeDistances = { (aaFlags & GrQuadAAFlags::kLeft)   ? 0.5f : 0.f,
                                  (aaFlags & GrQuadAAFlags::kBottom) ? 0.5f : 0.f,
                                  (aaFlags & GrQuadAAFlags::kTop)    ? 0.5f : 0.f,
                                  (aaFlags & GrQuadAAFlags::kRight)  ? 0.5f : 0.f };
            }
 
            // Write inner vertices first
            float coverage[4];
            fAAHelper.inset(edgeDistances, deviceQuad, localQuad).store(coverage);
            fWriteProc(&fVertexWriter, fVertexSpec, deviceQuad, localQuad, coverage, color,
                       geomSubset, uvSubset);
 
            // Then outer vertices, which use 0.f for their coverage. If the inset was degenerate
            // to a line (had all coverages < 1), tweak the outset distance so the outer frame's
            // narrow axis reaches out to 2px, which gives better animation under translation.
            const bool hairline = aaFlags == GrQuadAAFlags::kAll &&
                                  coverage[0] < 1.f &&
                                  coverage[1] < 1.f &&
                                  coverage[2] < 1.f &&
                                  coverage[3] < 1.f;
            if (hairline) {
                skvx::Vec<4, float> len = fAAHelper.getEdgeLengths();
                // Using max guards us against trying to scale a degenerate triangle edge of 0 len
                // up to 2px. The shuffles are so that edge 0's adjustment is based on the lengths
                // of its connecting edges (1 and 2), and so forth.
                skvx::Vec<4, float> maxWH = max(skvx::shuffle<1, 0, 3, 2>(len),
                                                skvx::shuffle<2, 3, 0, 1>(len));
                // wh + 2e' = 2, so e' = (2 - wh) / 2 => e' = e * (2 - wh). But if w or h > 1, then
                // 2 - wh < 1 and represents the non-narrow axis so clamp to 1.
                edgeDistances *= max(1.f, 2.f - maxWH);
            }
            fAAHelper.outset(edgeDistances, deviceQuad, localQuad);
            fWriteProc(&fVertexWriter, fVertexSpec, deviceQuad, localQuad, kZeroCoverage, color,
                       geomSubset, uvSubset);
        }
    } else {
        // No outsetting needed, just write a single quad with full coverage
        SkASSERT(fVertexSpec.coverageMode() == CoverageMode::kNone &&
                 !fVertexSpec.requiresGeometrySubset());
        fWriteProc(&fVertexWriter, fVertexSpec, deviceQuad, localQuad, kFullCoverage, color,
                   kIgnoredSubset, uvSubset);
    }
}

GetWriteQuadProc()

Tessellator::WriteQuadProc skgpu::ganesh::QuadPerEdgeAA::Tessellator::GetWriteQuadProc ( const VertexSpec &  spec )

static

Definition at line 326 of file QuadPerEdgeAA.cpp.

                                                                             {
    // All specialized writing functions requires 2D geometry and no geometry subset. This is not
    // the same as just checking device type vs. kRectilinear since non-AA general 2D quads do not
    // require a geometry subset and could then go through a fast path.
    if (spec.deviceQuadType() != GrQuad::Type::kPerspective && !spec.requiresGeometrySubset()) {
        CoverageMode mode = spec.coverageMode();
        if (spec.hasVertexColors()) {
            if (mode != CoverageMode::kWithPosition) {
                // Vertex colors, but no explicit coverage
                if (!spec.hasLocalCoords()) {
                    // Non-UV with vertex colors (possibly with coverage folded into alpha)
                    return write_2d_color;
                } else if (spec.localQuadType() != GrQuad::Type::kPerspective) {
                    // UV locals with vertex colors (possibly with coverage-as-alpha)
                    return spec.hasSubset() ? write_2d_color_uv_strict : write_2d_color_uv;
                }
            }
            // Else fall through; this is a spec that requires vertex colors and explicit coverage,
            // which means it's anti-aliased and the FPs don't support coverage as alpha, or
            // it uses 3D local coordinates.
        } else if (spec.hasLocalCoords() && spec.localQuadType() != GrQuad::Type::kPerspective) {
            if (mode == CoverageMode::kWithPosition) {
                // UV locals with explicit coverage
                return spec.hasSubset() ? write_2d_cov_uv_strict : write_2d_cov_uv;
            } else {
                SkASSERT(mode == CoverageMode::kNone);
                return spec.hasSubset() ? write_2d_uv_strict : write_2d_uv;
            }
        }
        // Else fall through to generic vertex function; this is a spec that has no vertex colors
        // and [no|uvr] local coords, which doesn't happen often enough to warrant specialization.
    }
 
    // Arbitrary spec hits the slow path
    return write_quad_generic;
}

Member Data Documentation

fAAHelper

GrQuadUtils::TessellationHelper skgpu::ganesh::QuadPerEdgeAA::Tessellator::fAAHelper

Definition at line 171 of file QuadPerEdgeAA.h.

fVertexSpec

VertexSpec skgpu::ganesh::QuadPerEdgeAA::Tessellator::fVertexSpec

Definition at line 172 of file QuadPerEdgeAA.h.

fVertexWriter

VertexWriter skgpu::ganesh::QuadPerEdgeAA::Tessellator::fVertexWriter

Definition at line 173 of file QuadPerEdgeAA.h.

fWriteProc

WriteQuadProc skgpu::ganesh::QuadPerEdgeAA::Tessellator::fWriteProc

Definition at line 174 of file QuadPerEdgeAA.h.

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The documentation for this class was generated from the following files:

• third_party/skia/src/gpu/ganesh/ops/QuadPerEdgeAA.h
• third_party/skia/src/gpu/ganesh/ops/QuadPerEdgeAA.cpp