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* Copyright 2015 Google Inc.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
#ifndef GrQuad_DEFINED
#define GrQuad_DEFINED
#include "include/core/SkMatrix.h"
#include "include/core/SkPoint.h"
#include "include/core/SkPoint3.h"
#include "include/private/SkVx.h"
#include "src/gpu/BufferWriter.h"
enum class GrQuadAAFlags;
* GrQuad is a collection of 4 points which can be used to represent an arbitrary quadrilateral. The
* points make a triangle strip with CCW triangles (top-left, bottom-left, top-right, bottom-right).
class GrQuad {
// Quadrilaterals can be classified in several useful ways that assist AA tessellation and other
// analysis when drawing, in particular, knowing if it was originally a rectangle transformed by
// certain types of matrices:
enum class Type {
// The 4 points remain an axis-aligned rectangle; their logical indices may not respect
// TL, BL, TR, BR ordering if the transform was a 90 degree rotation or mirror.
// The 4 points represent a rectangle subjected to a rotation, its corners are right angles.
// Arbitrary 2D quadrilateral; may have been a rectangle transformed with skew or some
// clipped polygon. Its w coordinates will all be 1.
// Even more general-purpose than kGeneral, this allows the w coordinates to be non-unity.
kLast = kPerspective
static const int kTypeCount = static_cast<int>(Type::kLast) + 1;
// This enforces W == 1 for non-perspective quads, but does not initialize X or Y.
GrQuad() = default;
GrQuad(const GrQuad&) = default;
explicit GrQuad(const SkRect& rect)
: fX{rect.fLeft, rect.fLeft, rect.fRight, rect.fRight}
, fY{rect.fTop, rect.fBottom, rect.fTop, rect.fBottom} {}
static GrQuad MakeFromRect(const SkRect&, const SkMatrix&);
// Creates a GrQuad from the quadrilateral 'pts', transformed by the matrix. The input
// points array is arranged as per SkRect::toQuad (top-left, top-right, bottom-right,
// bottom-left). The returned instance's point order will still be CCW tri-strip order.
static GrQuad MakeFromSkQuad(const SkPoint pts[4], const SkMatrix&);
GrQuad& operator=(const GrQuad&) = default;
SkPoint3 point3(int i) const { return {fX[i], fY[i], fW[i]}; }
SkPoint point(int i) const {
if (fType == Type::kPerspective) {
return {fX[i] / fW[i], fY[i] / fW[i]};
} else {
return {fX[i], fY[i]};
void writeVertex(int cornerIdx, skgpu::VertexWriter& w) const {
w << this->point(cornerIdx);
SkRect bounds() const {
if (fType == GrQuad::Type::kPerspective) {
return this->projectedBounds();
// Calculate min/max directly on the 4 floats, instead of loading/unloading into SIMD. Since
// there's no horizontal min/max, it's not worth it. Defining non-perspective case in header
// also leads to substantial performance boost due to inlining.
auto min = [](const float c[4]) { return std::min(std::min(c[0], c[1]),
std::min(c[2], c[3]));};
auto max = [](const float c[4]) { return std::max(std::max(c[0], c[1]),
std::max(c[2], c[3]));};
return { min(fX), min(fY), max(fX), max(fY) };
bool isFinite() const {
// If any coordinate is infinity or NaN, then multiplying it with 0 will make accum NaN
float accum = 0;
for (int i = 0; i < 4; ++i) {
accum *= fX[i];
accum *= fY[i];
accum *= fW[i];
SkASSERT(0 == accum || SkScalarIsNaN(accum));
return !SkScalarIsNaN(accum);
float x(int i) const { return fX[i]; }
float y(int i) const { return fY[i]; }
float w(int i) const { return fW[i]; }
float iw(int i) const { return sk_ieee_float_divide(1.f, fW[i]); }
skvx::Vec<4, float> x4f() const { return skvx::Vec<4, float>::Load(fX); }
skvx::Vec<4, float> y4f() const { return skvx::Vec<4, float>::Load(fY); }
skvx::Vec<4, float> w4f() const { return skvx::Vec<4, float>::Load(fW); }
skvx::Vec<4, float> iw4f() const { return 1.f / this->w4f(); }
Type quadType() const { return fType; }
bool hasPerspective() const { return fType == Type::kPerspective; }
// True if anti-aliasing affects this quad. Only valid when quadType == kAxisAligned
bool aaHasEffectOnRect() const;
// True if this quad is axis-aligned and still has its top-left corner at v0. Equivalently,
// quad == GrQuad(quad->bounds()). Axis-aligned quads with flips and rotations may exactly
// fill their bounds, but their vertex order will not match TL BL TR BR anymore.
bool asRect(SkRect* rect) const;
// The non-const pointers are provided to support modifying a GrQuad in-place, but care must be
// taken to keep its quad type aligned with the geometric nature of the new coordinates.
const float* xs() const { return fX; }
float* xs() { return fX; }
const float* ys() const { return fY; }
float* ys() { return fY; }
const float* ws() const { return fW; }
float* ws() { return fW; }
// Automatically ensures ws are 1 if new type is not perspective.
void setQuadType(Type newType) {
if (newType != Type::kPerspective && fType == Type::kPerspective) {
fW[0] = fW[1] = fW[2] = fW[3] = 1.f;
SkASSERT(newType == Type::kPerspective ||
(SkScalarNearlyEqual(fW[0], 1.f) && SkScalarNearlyEqual(fW[1], 1.f) &&
SkScalarNearlyEqual(fW[2], 1.f) && SkScalarNearlyEqual(fW[3], 1.f)));
fType = newType;
template<typename T>
friend class GrQuadListBase; // for access to fX, fY, fW
GrQuad(const skvx::Vec<4, float>& xs, const skvx::Vec<4, float>& ys, Type type)
: fType(type) {
SkASSERT(type != Type::kPerspective);;;
GrQuad(const skvx::Vec<4, float>& xs, const skvx::Vec<4, float>& ys,
const skvx::Vec<4, float>& ws, Type type)
: fW{} // Include fW in member initializer to avoid redundant default initializer
, fType(type) {;;;
// Defined in GrQuadUtils.cpp to share the coord clipping code
SkRect projectedBounds() const;
float fX[4];
float fY[4];
float fW[4] = {1.f, 1.f, 1.f, 1.f};
Type fType = Type::kAxisAligned;
template<> struct skgpu::VertexWriter::is_quad<GrQuad> : std::true_type {};
// A simple struct representing the common work unit of a pair of device and local coordinates, as
// well as the edge flags controlling anti-aliasing for the quadrilateral when drawn.
struct DrawQuad {
GrQuad fDevice;
GrQuad fLocal;
GrQuadAAFlags fEdgeFlags;