skgpu::graphite::AnalyticRRectRenderStep Class Reference

#include <AnalyticRRectRenderStep.h>

Inheritance diagram for skgpu::graphite::AnalyticRRectRenderStep:

Public Member Functions
	AnalyticRRectRenderStep (StaticBufferManager *bufferManager)
	~AnalyticRRectRenderStep () override
std::string	vertexSkSL () const override
const char *	fragmentCoverageSkSL () const override
void	writeVertices (DrawWriter *, const DrawParams &, skvx::ushort2 ssboIndices) const override
void	writeUniformsAndTextures (const DrawParams &, PipelineDataGatherer *) const override
Public Member Functions inherited from skgpu::graphite::RenderStep
virtual	~RenderStep ()=default
virtual std::string	texturesAndSamplersSkSL (const ResourceBindingRequirements &, int *nextBindingIndex) const
virtual const char *	fragmentColorSkSL () const
uint32_t	uniqueID () const
const char *	name () const
bool	requiresMSAA () const
bool	performsShading () const
bool	hasTextures () const
bool	emitsPrimitiveColor () const
bool	outsetBoundsForAA () const
Coverage	coverage () const
PrimitiveType	primitiveType () const
size_t	vertexStride () const
size_t	instanceStride () const
size_t	numUniforms () const
size_t	numVertexAttributes () const
size_t	numInstanceAttributes () const
SkSpan< const Uniform >	uniforms () const
SkSpan< const Attribute >	vertexAttributes () const
SkSpan< const Attribute >	instanceAttributes () const
SkSpan< const Varying >	varyings () const
const DepthStencilSettings &	depthStencilSettings () const
SkEnumBitMask< DepthStencilFlags >	depthStencilFlags () const

Additional Inherited Members
Static Public Member Functions inherited from skgpu::graphite::RenderStep
static const char *	ssboIndicesAttribute ()
static const char *	ssboIndicesVarying ()
Protected Types inherited from skgpu::graphite::RenderStep
enum class	Flags : unsigned {   kNone = 0b0000000 , kRequiresMSAA = 0b0000001 , kPerformsShading = 0b0000010 , kHasTextures = 0b0000100 ,   kEmitsCoverage = 0b0001000 , kLCDCoverage = 0b0010000 , kEmitsPrimitiveColor = 0b0100000 , kOutsetBoundsForAA = 0b1000000 }
Protected Member Functions inherited from skgpu::graphite::RenderStep
	RenderStep (std::string_view className, std::string_view variantName, SkEnumBitMask< Flags > flags, std::initializer_list< Uniform > uniforms, PrimitiveType primitiveType, DepthStencilSettings depthStencilSettings, SkSpan< const Attribute > vertexAttrs, SkSpan< const Attribute > instanceAttrs, SkSpan< const Varying > varyings={})

Detailed Description

Definition at line 17 of file AnalyticRRectRenderStep.h.

Constructor & Destructor Documentation

AnalyticRRectRenderStep()

skgpu::graphite::AnalyticRRectRenderStep::AnalyticRRectRenderStep

(

StaticBufferManager *

bufferManager

)

Definition at line 340 of file AnalyticRRectRenderStep.cpp.

        : RenderStep("AnalyticRRectRenderStep",
                     "",
                     Flags::kPerformsShading | Flags::kEmitsCoverage | Flags::kOutsetBoundsForAA,
                     /*uniforms=*/{},
                     PrimitiveType::kTriangleStrip,
                     kDirectDepthGreaterPass,
                     /*vertexAttrs=*/{
                            {"position", VertexAttribType::kFloat2, SkSLType::kFloat2},
                            {"normal", VertexAttribType::kFloat2, SkSLType::kFloat2},
                            // TODO: These values are all +1/0/-1, or +1/0, so could be packed
                            // much more densely than as three floats.
                            {"normalScale", VertexAttribType::kFloat, SkSLType::kFloat},
                            {"centerWeight", VertexAttribType::kFloat, SkSLType::kFloat}
                     },
                     /*instanceAttrs=*/
                            {{"xRadiiOrFlags", VertexAttribType::kFloat4, SkSLType::kFloat4},
                             {"radiiOrQuadXs", VertexAttribType::kFloat4, SkSLType::kFloat4},
                             {"ltrbOrQuadYs", VertexAttribType::kFloat4, SkSLType::kFloat4},
                             // XY stores center of rrect in local coords. Z and W store values to
                             // control interior fill behavior. Z can be -1, 0, or 1:
                             //   -1: A stroked interior where AA insets overlap, but isn't solid.
                             //    0: A stroked interior with no complications.
                             //    1: A solid interior (fill or sufficiently large stroke width).
                             // W specifies the size of the AA inset if it's >= 0, or signals that
                             // the inner curves intersect in a complex manner (rare).
                             {"center", VertexAttribType::kFloat4, SkSLType::kFloat4},
 
                             // TODO: pack depth and ssbo index into one 32-bit attribute, if we can
                             // go without needing both render step and paint ssbo index attributes.
                             {"depth", VertexAttribType::kFloat, SkSLType::kFloat},
                             {"ssboIndices", VertexAttribType::kUShort2, SkSLType::kUShort2},
 
                             {"mat0", VertexAttribType::kFloat3, SkSLType::kFloat3},
                             {"mat1", VertexAttribType::kFloat3, SkSLType::kFloat3},
                             {"mat2", VertexAttribType::kFloat3, SkSLType::kFloat3}},
                     /*varyings=*/{
                             // TODO: If the inverse transform is part of the draw's SSBO, we can
                             // reconstruct the Jacobian in the fragment shader using the existing
                             // local coordinates varying
                             {"jacobian", SkSLType::kFloat4}, // float2x2
                             // Distance to LTRB edges of unstroked shape. Depending on
                             // 'perPixelControl' these will either be local or device-space values.
                             {"edgeDistances", SkSLType::kFloat4}, // distance to LTRB edges
                             // TODO: These are constant for all fragments for a given instance,
                             // could we store them in the draw's SSBO?
                             {"xRadii", SkSLType::kFloat4},
                             {"yRadii", SkSLType::kFloat4},
                             // Matches the StrokeStyle struct (X is radius, Y < 0 is round join,
                             // Y = 0 is bevel, Y > 0 is miter join).
                             // TODO: These could easily be considered part of the draw's uniforms.
                             {"strokeParams", SkSLType::kFloat2},
                             // 'perPixelControl' is a tightly packed description of how to
                             // evaluate the possible edges that influence coverage in a pixel.
                             // The decision points and encoded values are spread across X and Y
                             // so that they are consistent regardless of whether or not MSAA is
                             // used and does not require centroid sampling.
                             //
                             // The signs of values are used to determine the type of coverage to
                             // calculate in the fragment shader and depending on the state, extra
                             // varying state is encoded in the fields:
                             //  - A positive X value overrides all per-pixel coverage calculations
                             //    and sets the pixel to full coverage. Y is ignored in this case.
                             //  - A zero X value represents a solid interior shape.
                             //  - X much less than 0 represents bidirectional coverage for a
                             //    stroke, using a sufficiently negative value to avoid
                             //    extrapolation from fill triangles. For actual shapes with
                             //    bidirectional coverage, the fill triangles are zero area.
                             //
                             //  - Y much greater than 0 takes precedence over the latter two X
                             //    rules and signals that 'edgeDistances' holds device-space values
                             //    and does not require additional per-pixel calculations. The
                             //    coverage scale is encoded as (1+scale*w) and the bias is
                             //    reconstructed from that. X is always 0 for non-fill triangles
                             //    since device-space edge distance is only used for solid interiors
                             //  - Otherwise, any negative Y value represents an additional
                             //    reduction in coverage due to a device-space outset. It is clamped
                             //    below 0 to avoid adding coverage from extrapolation.
                             {"perPixelControl", SkSLType::kFloat2},
                     }) {
    // Initialize the static buffers we'll use when recording draw calls.
    // NOTE: Each instance of this RenderStep gets its own copy of the data. Since there should only
    // ever be one AnalyticRRectRenderStep at a time, this shouldn't be an issue.
    write_vertex_buffer(bufferManager->getVertexWriter(sizeof(Vertex) * kVertexCount,
                                                       &fVertexBuffer));
    write_index_buffer(bufferManager->getIndexWriter(sizeof(uint16_t) * kIndexCount,
                                                     &fIndexBuffer));
}

~AnalyticRRectRenderStep()

skgpu::graphite::AnalyticRRectRenderStep::~AnalyticRRectRenderStep ( )

override

Definition at line 429 of file AnalyticRRectRenderStep.cpp.

{}

Member Function Documentation

fragmentCoverageSkSL()

const char * skgpu::graphite::AnalyticRRectRenderStep::fragmentCoverageSkSL ( ) const

overridevirtual

Reimplemented from skgpu::graphite::RenderStep.

Definition at line 446 of file AnalyticRRectRenderStep.cpp.

                                                                {
    // The returned SkSL must write its coverage into a 'half4 outputCoverage' variable (defined in
    // the calling code) with the actual coverage splatted out into all four channels.
    return "outputCoverage = analytic_rrect_coverage_fn(sk_FragCoord, "
                                                       "jacobian, "
                                                       "edgeDistances, "
                                                       "xRadii, "
                                                       "yRadii, "
                                                       "strokeParams, "
                                                       "perPixelControl);";
}

vertexSkSL()

std::string skgpu::graphite::AnalyticRRectRenderStep::vertexSkSL ( ) const

overridevirtual

Implements skgpu::graphite::RenderStep.

Definition at line 431 of file AnalyticRRectRenderStep.cpp.

                                                    {
    // Returns the body of a vertex function, which must define a float4 devPosition variable and
    // must write to an already-defined float2 stepLocalCoords variable.
    return "float4 devPosition = analytic_rrect_vertex_fn("
                   // Vertex Attributes
                   "position, normal, normalScale, centerWeight, "
                   // Instance Attributes
                   "xRadiiOrFlags, radiiOrQuadXs, ltrbOrQuadYs, center, depth, "
                   "float3x3(mat0, mat1, mat2), "
                   // Varyings
                   "jacobian, edgeDistances, xRadii, yRadii, strokeParams, perPixelControl, "
                   // Render Step
                   "stepLocalCoords);\n";
}

writeUniformsAndTextures()

void skgpu::graphite::AnalyticRRectRenderStep::writeUniformsAndTextures ( const DrawParams &  , PipelineDataGatherer *    ) const

overridevirtual

Implements skgpu::graphite::RenderStep.

Definition at line 613 of file AnalyticRRectRenderStep.cpp.

                                                                                    {
    // All data is uploaded as instance attributes, so no uniforms are needed.
}

writeVertices()

void skgpu::graphite::AnalyticRRectRenderStep::writeVertices ( DrawWriter *  writer, const DrawParams &  params, skvx::ushort2  ssboIndices  ) const

overridevirtual

Implements skgpu::graphite::RenderStep.

Definition at line 458 of file AnalyticRRectRenderStep.cpp.

                                                                           {
    SkASSERT(params.geometry().isShape() || params.geometry().isEdgeAAQuad());
 
    DrawWriter::Instances instance{*writer, fVertexBuffer, fIndexBuffer, kIndexCount};
    auto vw = instance.append(1);
 
    // The bounds of a rect is the rect, and the bounds of a rrect is tight (== SkRRect::getRect()).
    Rect bounds = params.geometry().bounds();
 
    // aaRadius will be set to a negative value to signal a complex self-intersection that has to
    // be calculated in the vertex shader.
    float aaRadius = params.transform().localAARadius(bounds);
    float strokeInset = 0.f;
    float centerWeight = kSolidInterior;
 
    if (params.isStroke()) {
         // EdgeAAQuads are not stroked so we know it's a Shape, but we support rects, rrects, and
         // lines that all need to be converted to the same form.
        const Shape& shape = params.geometry().shape();
 
        SkASSERT(params.strokeStyle().halfWidth() >= 0.f);
        SkASSERT(shape.isRect() || shape.isLine() || params.strokeStyle().halfWidth() == 0.f ||
                 (shape.isRRect() && SkRRectPriv::AllCornersCircular(shape.rrect())));
 
        float strokeRadius = params.strokeStyle().halfWidth();
 
        skvx::float2 size = shape.isLine() ? skvx::float2(length(shape.p1() - shape.p0()), 0.f)
                                           : bounds.size(); // rect or [r]rect
 
        skvx::float2 innerGap = size - 2.f * params.strokeStyle().halfWidth();
        if (any(innerGap <= 0.f) && strokeRadius > 0.f) {
            // AA inset intersections are measured from the *outset* and remain marked as "solid"
            strokeInset = -strokeRadius;
        } else {
            // This will be upgraded to kFilledStrokeInterior if insets intersect
            centerWeight = kStrokeInterior;
            strokeInset = strokeRadius;
        }
 
        skvx::float4 xRadii = shape.isRRect() ? load_x_radii(shape.rrect()) : skvx::float4(0.f);
        if (strokeRadius > 0.f || shape.isLine()) {
            // Regular strokes only need to upload 4 corner radii; hairline lines can be uploaded in
            // the same manner since it has no real corner radii.
            float joinStyle = params.strokeStyle().joinLimit();
            float lineFlag = shape.isLine() ? 1.f : 0.f;
            auto empty = size == 0.f;
 
            // Points and lines produce caps instead of joins. However, the capped geometry is
            // visually equivalent to a joined, stroked [r]rect of the paired join style.
            if (shape.isLine() || all(empty)) {
                // However, butt-cap points are defined not to produce any geometry, so that combo
                // should have been rejected earlier.
                SkASSERT(shape.isLine() || params.strokeStyle().cap() != SkPaint::kButt_Cap);
                switch(params.strokeStyle().cap()) {
                    case SkPaint::kRound_Cap:  joinStyle = -1.f; break; // round cap == round join
                    case SkPaint::kButt_Cap:   joinStyle =  0.f; break; // butt cap == bevel join
                    case SkPaint::kSquare_Cap: joinStyle =  1.f; break; // square cap == miter join
                }
            } else if (params.strokeStyle().isMiterJoin()) {
                // Normal corners are 90-degrees so become beveled if the miter limit is < sqrt(2).
                // If the [r]rect has a width or height of 0, the corners are actually 180-degrees,
                // so the must always be beveled (or, equivalently, butt-capped).
                if (params.strokeStyle().miterLimit() < SK_ScalarSqrt2 || any(empty)) {
                    joinStyle = 0.f; // == bevel (or butt if width or height are zero)
                } else {
                    // Discard actual miter limit because a 90-degree corner never exceeds it.
                    joinStyle = 1.f;
                }
            } // else no join style correction needed for non-empty geometry or round joins
 
            // Write a negative value outside [-1, 0] to signal a stroked shape, the line flag, then
            // the style params, followed by corner radii and coords.
            vw << -2.f << lineFlag << strokeRadius << joinStyle << xRadii
               << (shape.isLine() ? shape.line() : bounds.ltrb());
        } else {
            // Write -2 - cornerRadii to encode the X radii in such a way to trigger stroking but
            // guarantee the 2nd field is non-zero to signal hairline. Then we upload Y radii as
            // well to allow for elliptical hairlines.
            skvx::float4 yRadii = shape.isRRect() ? load_y_radii(shape.rrect()) : skvx::float4(0.f);
            vw << (-2.f - xRadii) << yRadii << bounds.ltrb();
        }
    } else {
        // Empty fills should not have been recorded at all.
        SkASSERT(!bounds.isEmptyNegativeOrNaN());
 
        if (params.geometry().isEdgeAAQuad()) {
            // NOTE: If quad.isRect() && quad.edgeFlags() == kAll, the written data is identical to
            // Shape.isRect() case below.
            const EdgeAAQuad& quad = params.geometry().edgeAAQuad();
 
            // If all edges are non-AA, set localAARadius to 0 so that the fill triangles cover the
            // entire shape. Otherwise leave it as-is for the full AA rect case; in the event it's
            // mixed-AA or a quad, it'll be converted to complex insets down below.
            if (quad.edgeFlags() == EdgeAAQuad::Flags::kNone) {
                aaRadius = 0.f;
            }
 
            // -1 for AA on, 0 for AA off
            auto edgeSigns = skvx::float4{quad.edgeFlags() & AAFlags::kLeft   ? -1.f : 0.f,
                                          quad.edgeFlags() & AAFlags::kTop    ? -1.f : 0.f,
                                          quad.edgeFlags() & AAFlags::kRight  ? -1.f : 0.f,
                                          quad.edgeFlags() & AAFlags::kBottom ? -1.f : 0.f};
 
            // The vertex shader expects points to be in clockwise order. EdgeAAQuad is the only
            // shape that *might* have counter-clockwise input.
            if (is_clockwise(quad)) {
                vw << edgeSigns << quad.xs() << quad.ys();
            } else {
                vw << skvx::shuffle<2,1,0,3>(edgeSigns)  // swap left and right AA bits
                   << skvx::shuffle<1,0,3,2>(quad.xs())  // swap TL with TR, and BL with BR
                   << skvx::shuffle<1,0,3,2>(quad.ys()); //   ""
            }
        } else {
            const Shape& shape = params.geometry().shape();
            // Filled lines are empty by definition, so they shouldn't have been recorded
            SkASSERT(!shape.isLine());
 
            if (shape.isRect() || (shape.isRRect() && shape.rrect().isRect())) {
                // Rectangles (or rectangles embedded in an SkRRect) are converted to the
                // quadrilateral case, but with all edges anti-aliased (== -1).
                skvx::float4 ltrb = bounds.ltrb();
                vw << /*edge flags*/ skvx::float4(-1.f)
                   << /*xs*/ skvx::shuffle<0,2,2,0>(ltrb)
                   << /*ys*/ skvx::shuffle<1,1,3,3>(ltrb);
            } else {
                // A filled rounded rectangle, so make sure at least one corner radii > 0 or the
                // shader won't detect it as a rounded rect.
                SkASSERT(any(load_x_radii(shape.rrect()) > 0.f));
 
                vw << load_x_radii(shape.rrect()) << load_y_radii(shape.rrect()) << bounds.ltrb();
            }
        }
    }
 
    if (opposite_insets_intersect(params.geometry(), strokeInset, aaRadius)) {
        aaRadius = kComplexAAInsets;
        if (centerWeight == kStrokeInterior) {
            centerWeight = kFilledStrokeInterior;
        }
    }
 
    // All instance types share the remaining instance attribute definitions
    const SkM44& m = params.transform().matrix();
    auto center = params.geometry().isEdgeAAQuad() ? quad_center(params.geometry().edgeAAQuad())
                                                   : bounds.center();
    vw << center << centerWeight << aaRadius
       << params.order().depthAsFloat()
       << ssboIndices
       << m.rc(0,0) << m.rc(1,0) << m.rc(3,0)  // mat0
       << m.rc(0,1) << m.rc(1,1) << m.rc(3,1)  // mat1
       << m.rc(0,3) << m.rc(1,3) << m.rc(3,3); // mat2
}

---

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

• third_party/skia/src/gpu/graphite/render/AnalyticRRectRenderStep.h
• third_party/skia/src/gpu/graphite/render/AnalyticRRectRenderStep.cpp