SkPatchUtils Class Reference

#include <SkPatchUtils.h>

Public Types
enum	{ kNumCtrlPts = 12 , kNumCorners = 4 , kNumPtsCubic = 4 }

Static Public Member Functions
static void	GetTopCubic (const SkPoint cubics[12], SkPoint points[4])
static void	GetBottomCubic (const SkPoint cubics[12], SkPoint points[4])
static void	GetLeftCubic (const SkPoint cubics[12], SkPoint points[4])
static void	GetRightCubic (const SkPoint cubics[12], SkPoint points[4])
static SkISize	GetLevelOfDetail (const SkPoint cubics[12], const SkMatrix *matrix)
static sk_sp< SkVertices >	MakeVertices (const SkPoint cubics[12], const SkColor colors[4], const SkPoint texCoords[4], int lodX, int lodY, SkColorSpace *colorSpace=nullptr)

Detailed Description

Definition at line 20 of file SkPatchUtils.h.

Member Enumeration Documentation

anonymous enum

anonymous enum

Enumerator
kNumCtrlPts
kNumCorners
kNumPtsCubic

Definition at line 24 of file SkPatchUtils.h.

         {
        kNumCtrlPts = 12,
        kNumCorners = 4,
        kNumPtsCubic = 4
    };

Member Function Documentation

GetBottomCubic()

void SkPatchUtils::GetBottomCubic ( const SkPoint  cubics[12], SkPoint  points[4]  )

static

Get the points corresponding to the bottom cubic of cubics.

Definition at line 219 of file SkPatchUtils.cpp.

                                                                             {
    points[0] = cubics[kBottomP0_CubicCtrlPts];
    points[1] = cubics[kBottomP1_CubicCtrlPts];
    points[2] = cubics[kBottomP2_CubicCtrlPts];
    points[3] = cubics[kBottomP3_CubicCtrlPts];
}

GetLeftCubic()

void SkPatchUtils::GetLeftCubic ( const SkPoint  cubics[12], SkPoint  points[4]  )

static

Get the points corresponding to the left cubic of cubics.

Definition at line 226 of file SkPatchUtils.cpp.

                                                                           {
    points[0] = cubics[kLeftP0_CubicCtrlPts];
    points[1] = cubics[kLeftP1_CubicCtrlPts];
    points[2] = cubics[kLeftP2_CubicCtrlPts];
    points[3] = cubics[kLeftP3_CubicCtrlPts];
}

GetLevelOfDetail()

SkISize SkPatchUtils::GetLevelOfDetail ( const SkPoint  cubics[12], const SkMatrix *  matrix  )

static

Method that calculates a level of detail (number of subdivisions) for a patch in both axis.

Definition at line 182 of file SkPatchUtils.cpp.

                                                                                       {
    // Approximate length of each cubic.
    SkPoint pts[kNumPtsCubic];
    SkPatchUtils::GetTopCubic(cubics, pts);
    matrix->mapPoints(pts, kNumPtsCubic);
    SkScalar topLength = approx_arc_length(pts, kNumPtsCubic);
 
    SkPatchUtils::GetBottomCubic(cubics, pts);
    matrix->mapPoints(pts, kNumPtsCubic);
    SkScalar bottomLength = approx_arc_length(pts, kNumPtsCubic);
 
    SkPatchUtils::GetLeftCubic(cubics, pts);
    matrix->mapPoints(pts, kNumPtsCubic);
    SkScalar leftLength = approx_arc_length(pts, kNumPtsCubic);
 
    SkPatchUtils::GetRightCubic(cubics, pts);
    matrix->mapPoints(pts, kNumPtsCubic);
    SkScalar rightLength = approx_arc_length(pts, kNumPtsCubic);
 
    if (topLength < 0 || bottomLength < 0 || leftLength < 0 || rightLength < 0) {
        return {0, 0};  // negative length is a sentinel for bad length (i.e. non-finite)
    }
 
    // Level of detail per axis, based on the larger side between top and bottom or left and right
    int lodX = static_cast<int>(std::max(topLength, bottomLength) / kPartitionSize);
    int lodY = static_cast<int>(std::max(leftLength, rightLength) / kPartitionSize);
 
    return SkISize::Make(std::max(8, lodX), std::max(8, lodY));
}

GetRightCubic()

void SkPatchUtils::GetRightCubic ( const SkPoint  cubics[12], SkPoint  points[4]  )

static

Get the points corresponding to the right cubic of cubics.

Definition at line 233 of file SkPatchUtils.cpp.

                                                                            {
    points[0] = cubics[kRightP0_CubicCtrlPts];
    points[1] = cubics[kRightP1_CubicCtrlPts];
    points[2] = cubics[kRightP2_CubicCtrlPts];
    points[3] = cubics[kRightP3_CubicCtrlPts];
}

GetTopCubic()

void SkPatchUtils::GetTopCubic ( const SkPoint  cubics[12], SkPoint  points[4]  )

static

Get the points corresponding to the top cubic of cubics.

Definition at line 212 of file SkPatchUtils.cpp.

                                                                          {
    points[0] = cubics[kTopP0_CubicCtrlPts];
    points[1] = cubics[kTopP1_CubicCtrlPts];
    points[2] = cubics[kTopP2_CubicCtrlPts];
    points[3] = cubics[kTopP3_CubicCtrlPts];
}

MakeVertices()

sk_sp< SkVertices > SkPatchUtils::MakeVertices ( const SkPoint  cubics[12], const SkColor  colors[4], const SkPoint  texCoords[4], int  lodX, int  lodY, SkColorSpace *  colorSpace = nullptr  )

static

Definition at line 256 of file SkPatchUtils.cpp.

                                                                       {
    if (lodX < 1 || lodY < 1 || nullptr == cubics) {
        return nullptr;
    }
 
    // check for overflow in multiplication
    const int64_t lodX64 = (lodX + 1),
    lodY64 = (lodY + 1),
    mult64 = lodX64 * lodY64;
    if (mult64 > SK_MaxS32) {
        return nullptr;
    }
 
    // Treat null interpolation space as sRGB.
    if (!colorSpace) {
        colorSpace = sk_srgb_singleton();
    }
 
    int vertexCount = SkToS32(mult64);
    // it is recommended to generate draw calls of no more than 65536 indices, so we never generate
    // more than 60000 indices. To accomplish that we resize the LOD and vertex count
    if (vertexCount > 10000 || lodX > 200 || lodY > 200) {
        float weightX = static_cast<float>(lodX) / (lodX + lodY);
        float weightY = static_cast<float>(lodY) / (lodX + lodY);
 
        // 200 comes from the 100 * 2 which is the max value of vertices because of the limit of
        // 60000 indices ( sqrt(60000 / 6) that comes from data->fIndexCount = lodX * lodY * 6)
        // Need a min of 1 since we later divide by lod
        lodX = std::max(1, sk_float_floor2int_no_saturate(weightX * 200));
        lodY = std::max(1, sk_float_floor2int_no_saturate(weightY * 200));
        vertexCount = (lodX + 1) * (lodY + 1);
    }
    const int indexCount = lodX * lodY * 6;
    uint32_t flags = 0;
    if (srcTexCoords) {
        flags |= SkVertices::kHasTexCoords_BuilderFlag;
    }
    if (srcColors) {
        flags |= SkVertices::kHasColors_BuilderFlag;
    }
 
    SkSTArenaAlloc<2048> alloc;
    SkPMColor4f* cornerColors = srcColors ? alloc.makeArray<SkPMColor4f>(4) : nullptr;
    SkPMColor4f* tmpColors = srcColors ? alloc.makeArray<SkPMColor4f>(vertexCount) : nullptr;
 
    SkVertices::Builder builder(SkVertices::kTriangles_VertexMode, vertexCount, indexCount, flags);
    SkPoint* pos = builder.positions();
    SkPoint* texs = builder.texCoords();
    uint16_t* indices = builder.indices();
 
    if (cornerColors) {
        skcolor_to_float(cornerColors, srcColors, kNumCorners, colorSpace);
    }
 
    SkPoint pts[kNumPtsCubic];
    SkPatchUtils::GetBottomCubic(cubics, pts);
    FwDCubicEvaluator fBottom(pts);
    SkPatchUtils::GetTopCubic(cubics, pts);
    FwDCubicEvaluator fTop(pts);
    SkPatchUtils::GetLeftCubic(cubics, pts);
    FwDCubicEvaluator fLeft(pts);
    SkPatchUtils::GetRightCubic(cubics, pts);
    FwDCubicEvaluator fRight(pts);
 
    fBottom.restart(lodX);
    fTop.restart(lodX);
 
    SkScalar u = 0.0f;
    int stride = lodY + 1;
    for (int x = 0; x <= lodX; x++) {
        SkPoint bottom = fBottom.next(), top = fTop.next();
        fLeft.restart(lodY);
        fRight.restart(lodY);
        SkScalar v = 0.f;
        for (int y = 0; y <= lodY; y++) {
            int dataIndex = x * (lodY + 1) + y;
 
            SkPoint left = fLeft.next(), right = fRight.next();
 
            SkPoint s0 = SkPoint::Make((1.0f - v) * top.x() + v * bottom.x(),
                                       (1.0f - v) * top.y() + v * bottom.y());
            SkPoint s1 = SkPoint::Make((1.0f - u) * left.x() + u * right.x(),
                                       (1.0f - u) * left.y() + u * right.y());
            SkPoint s2 = SkPoint::Make(
                                       (1.0f - v) * ((1.0f - u) * fTop.getCtrlPoints()[0].x()
                                                     + u * fTop.getCtrlPoints()[3].x())
                                       + v * ((1.0f - u) * fBottom.getCtrlPoints()[0].x()
                                              + u * fBottom.getCtrlPoints()[3].x()),
                                       (1.0f - v) * ((1.0f - u) * fTop.getCtrlPoints()[0].y()
                                                     + u * fTop.getCtrlPoints()[3].y())
                                       + v * ((1.0f - u) * fBottom.getCtrlPoints()[0].y()
                                              + u * fBottom.getCtrlPoints()[3].y()));
            pos[dataIndex] = s0 + s1 - s2;
 
            if (cornerColors) {
                bilerp(u, v, skvx::float4::Load(cornerColors[kTopLeft_Corner].vec()),
                             skvx::float4::Load(cornerColors[kTopRight_Corner].vec()),
                             skvx::float4::Load(cornerColors[kBottomLeft_Corner].vec()),
                             skvx::float4::Load(cornerColors[kBottomRight_Corner].vec()))
                    .store(tmpColors[dataIndex].vec());
            }
 
            if (texs) {
                texs[dataIndex] = SkPoint::Make(bilerp(u, v, srcTexCoords[kTopLeft_Corner].x(),
                                                       srcTexCoords[kTopRight_Corner].x(),
                                                       srcTexCoords[kBottomLeft_Corner].x(),
                                                       srcTexCoords[kBottomRight_Corner].x()),
                                                bilerp(u, v, srcTexCoords[kTopLeft_Corner].y(),
                                                       srcTexCoords[kTopRight_Corner].y(),
                                                       srcTexCoords[kBottomLeft_Corner].y(),
                                                       srcTexCoords[kBottomRight_Corner].y()));
 
            }
 
            if(x < lodX && y < lodY) {
                int i = 6 * (x * lodY + y);
                indices[i] = x * stride + y;
                indices[i + 1] = x * stride + 1 + y;
                indices[i + 2] = (x + 1) * stride + 1 + y;
                indices[i + 3] = indices[i];
                indices[i + 4] = indices[i + 2];
                indices[i + 5] = (x + 1) * stride + y;
            }
            v = SkTPin(v + 1.f / lodY, 0.0f, 1.0f);
        }
        u = SkTPin(u + 1.f / lodX, 0.0f, 1.0f);
    }
 
    if (tmpColors) {
        float_to_skcolor(builder.colors(), tmpColors, vertexCount, colorSpace);
    }
    return builder.detach();
}

---

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

• third_party/skia/src/utils/SkPatchUtils.h
• third_party/skia/src/utils/SkPatchUtils.cpp