287 lines
10 KiB
C++
287 lines
10 KiB
C++
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/*
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* Copyright 2016 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "SampleCode.h"
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#include "SkAnimTimer.h"
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#include "SkColor.h"
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#include "SkRandom.h"
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#include "SkRRect.h"
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#include "SkSVGDOM.h"
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#include "SkSVGG.h"
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#include "SkSVGPath.h"
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#include "SkSVGRect.h"
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#include "SkSVGSVG.h"
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namespace {
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static const SkRect kBounds = SkRect::MakeLTRB(0.1f, 0.1f, 0.9f, 0.9f);
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static const SkSize kPaddleSize = SkSize::Make(0.03f, 0.1f);
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static const SkScalar kBallSize = 0.04f;
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static const SkScalar kShadowOpacity = 0.40f;
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static const SkScalar kShadowParallax = 0.04f;
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static const SkScalar kBackgroundStroke = 0.01f;
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static const uint32_t kBackgroundDashCount = 20;
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static const SkScalar kBallSpeedMax = 0.0020f;
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static const SkScalar kBallSpeedMin = 0.0005f;
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static const SkScalar kBallSpeedFuzz = 0.0002f;
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static const SkScalar kTimeScaleMin = 0.0f;
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static const SkScalar kTimeScaleMax = 5.0f;
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// Box the value within [min, max), by applying infinite reflection on the interval endpoints.
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SkScalar box_reflect(SkScalar v, SkScalar min, SkScalar max) {
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const SkScalar intervalLen = max - min;
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SkASSERT(intervalLen > 0);
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// f(v) is periodic in 2 * intervalLen: one normal progression + one reflection
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const SkScalar P = intervalLen * 2;
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// relative to P origin
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const SkScalar vP = v - min;
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// map to [0, P)
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const SkScalar vMod = (vP < 0) ? P - SkScalarMod(-vP, P) : SkScalarMod(vP, P);
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// reflect if needed, to map to [0, intervalLen)
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const SkScalar vInterval = vMod < intervalLen ? vMod : P - vMod;
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// finally, reposition relative to min
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return vInterval + min;
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}
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// Compute <t, y> for the trajectory intersection with the next vertical edge.
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std::tuple<SkScalar, SkScalar> find_yintercept(const SkPoint& pos, const SkVector& spd,
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const SkRect& box) {
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const SkScalar edge = spd.fX > 0 ? box.fRight : box.fLeft;
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const SkScalar t = (edge - pos.fX) / spd.fX;
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SkASSERT(t >= 0);
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const SkScalar dY = t * spd.fY;
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return std::make_tuple(t, box_reflect(pos.fY + dY, box.fTop, box.fBottom));
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}
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sk_sp<SkSVGRect> make_svg_rrect(const SkRRect& rrect) {
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sk_sp<SkSVGRect> node = SkSVGRect::Make();
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node->setX(SkSVGLength(rrect.rect().x()));
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node->setY(SkSVGLength(rrect.rect().y()));
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node->setWidth(SkSVGLength(rrect.width()));
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node->setHeight(SkSVGLength(rrect.height()));
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node->setRx(SkSVGLength(rrect.getSimpleRadii().x()));
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node->setRy(SkSVGLength(rrect.getSimpleRadii().y()));
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return node;
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}
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} // anonymous ns
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class SVGPongView final : public SampleView {
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public:
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SVGPongView() {}
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protected:
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void onOnceBeforeDraw() override {
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const SkRect fieldBounds = kBounds.makeOutset(kBallSize / 2, kBallSize / 2);
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const SkRRect ball = SkRRect::MakeOval(SkRect::MakeWH(kBallSize, kBallSize));
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const SkRRect paddle = SkRRect::MakeRectXY(SkRect::MakeWH(kPaddleSize.width(),
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kPaddleSize.height()),
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kPaddleSize.width() / 2,
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kPaddleSize.width() / 2);
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fBall.initialize(ball,
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SK_ColorGREEN,
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SkPoint::Make(kBounds.centerX(), kBounds.centerY()),
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SkVector::Make(fRand.nextRangeScalar(kBallSpeedMin, kBallSpeedMax),
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fRand.nextRangeScalar(kBallSpeedMin, kBallSpeedMax)));
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fPaddle0.initialize(paddle,
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SK_ColorBLUE,
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SkPoint::Make(fieldBounds.left() - kPaddleSize.width() / 2,
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fieldBounds.centerY()),
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SkVector::Make(0, 0));
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fPaddle1.initialize(paddle,
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SK_ColorRED,
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SkPoint::Make(fieldBounds.right() + kPaddleSize.width() / 2,
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fieldBounds.centerY()),
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SkVector::Make(0, 0));
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// Background decoration.
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SkPath bgPath;
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bgPath.moveTo(kBounds.left() , fieldBounds.top());
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bgPath.lineTo(kBounds.right(), fieldBounds.top());
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bgPath.moveTo(kBounds.left() , fieldBounds.bottom());
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bgPath.lineTo(kBounds.right(), fieldBounds.bottom());
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// TODO: stroke-dash support would come in handy right about now.
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for (uint32_t i = 0; i < kBackgroundDashCount; ++i) {
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bgPath.moveTo(kBounds.centerX(),
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kBounds.top() + (i + 0.25f) * kBounds.height() / kBackgroundDashCount);
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bgPath.lineTo(kBounds.centerX(),
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kBounds.top() + (i + 0.75f) * kBounds.height() / kBackgroundDashCount);
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}
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sk_sp<SkSVGPath> bg = SkSVGPath::Make();
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bg->setPath(bgPath);
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bg->setFill(SkSVGPaint(SkSVGPaint::Type::kNone));
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bg->setStroke(SkSVGPaint(SkSVGColorType(SK_ColorBLACK)));
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bg->setStrokeWidth(SkSVGLength(kBackgroundStroke));
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// Build the SVG DOM tree.
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sk_sp<SkSVGSVG> root = SkSVGSVG::Make();
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root->appendChild(std::move(bg));
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root->appendChild(fPaddle0.shadowNode);
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root->appendChild(fPaddle1.shadowNode);
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root->appendChild(fBall.shadowNode);
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root->appendChild(fPaddle0.objectNode);
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root->appendChild(fPaddle1.objectNode);
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root->appendChild(fBall.objectNode);
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// Handle everything in a normalized 1x1 space.
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root->setViewBox(SkSVGViewBoxType(SkRect::MakeWH(1, 1)));
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fDom = sk_sp<SkSVGDOM>(new SkSVGDOM(SkSize::Make(this->width(), this->height())));
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fDom->setRoot(std::move(root));
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// Off we go.
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this->updatePaddleStrategy();
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}
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bool onQuery(SkEvent* evt) override {
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if (SampleCode::TitleQ(*evt)) {
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SampleCode::TitleR(evt, "SVGPong");
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return true;
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}
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SkUnichar uni;
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if (SampleCode::CharQ(*evt, &uni)) {
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switch (uni) {
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case '[':
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fTimeScale = SkTPin(fTimeScale - 0.1f, kTimeScaleMin, kTimeScaleMax);
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return true;
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case ']':
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fTimeScale = SkTPin(fTimeScale + 0.1f, kTimeScaleMin, kTimeScaleMax);
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return true;
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default:
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break;
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}
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}
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return this->INHERITED::onQuery(evt);
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}
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void onSizeChange() override {
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if (fDom) {
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fDom->setContainerSize(SkSize::Make(this->width(), this->height()));
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}
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this->INHERITED::onSizeChange();
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}
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void onDrawContent(SkCanvas* canvas) override {
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fDom->render(canvas);
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}
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bool onAnimate(const SkAnimTimer& timer) override {
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SkScalar dt = (timer.msec() - fLastTick) * fTimeScale;
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fLastTick = timer.msec();
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fPaddle0.posTick(dt);
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fPaddle1.posTick(dt);
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fBall.posTick(dt);
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this->enforceConstraints();
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fPaddle0.updateDom();
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fPaddle1.updateDom();
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fBall.updateDom();
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return true;
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}
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private:
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struct Object {
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void initialize(const SkRRect& rrect, SkColor color,
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const SkPoint& p, const SkVector& s) {
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objectNode = make_svg_rrect(rrect);
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objectNode->setFill(SkSVGPaint(SkSVGColorType(color)));
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shadowNode = make_svg_rrect(rrect);
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shadowNode->setFillOpacity(SkSVGNumberType(kShadowOpacity));
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pos = p;
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spd = s;
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size = SkSize::Make(rrect.width(), rrect.height());
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}
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void posTick(SkScalar dt) {
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pos += spd * dt;
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}
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void updateDom() {
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const SkPoint corner = pos - SkPoint::Make(size.width() / 2, size.height() / 2);
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objectNode->setX(SkSVGLength(corner.x()));
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objectNode->setY(SkSVGLength(corner.y()));
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// Simulate parallax shadow for a centered light source.
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SkPoint shadowOffset = pos - SkPoint::Make(kBounds.centerX(), kBounds.centerY());
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shadowOffset.scale(kShadowParallax);
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const SkPoint shadowCorner = corner + shadowOffset;
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shadowNode->setX(SkSVGLength(shadowCorner.x()));
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shadowNode->setY(SkSVGLength(shadowCorner.y()));
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}
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sk_sp<SkSVGRect> objectNode;
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sk_sp<SkSVGRect> shadowNode;
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SkPoint pos;
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SkVector spd;
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SkSize size;
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};
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void enforceConstraints() {
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// Perfect vertical reflection.
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if (fBall.pos.fY < kBounds.fTop || fBall.pos.fY >= kBounds.fBottom) {
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fBall.spd.fY = -fBall.spd.fY;
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fBall.pos.fY = box_reflect(fBall.pos.fY, kBounds.fTop, kBounds.fBottom);
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}
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// Horizontal bounce - introduces a speed fuzz.
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if (fBall.pos.fX < kBounds.fLeft || fBall.pos.fX >= kBounds.fRight) {
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fBall.spd.fX = this->fuzzBallSpeed(-fBall.spd.fX);
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fBall.spd.fY = this->fuzzBallSpeed(fBall.spd.fY);
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fBall.pos.fX = box_reflect(fBall.pos.fX, kBounds.fLeft, kBounds.fRight);
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this->updatePaddleStrategy();
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}
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}
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SkScalar fuzzBallSpeed(SkScalar spd) {
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// The speed limits are absolute values.
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const SkScalar sign = spd >= 0 ? 1.0f : -1.0f;
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const SkScalar fuzzed = fabs(spd) + fRand.nextRangeScalar(-kBallSpeedFuzz, kBallSpeedFuzz);
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return sign * SkTPin(fuzzed, kBallSpeedMin, kBallSpeedMax);
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}
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void updatePaddleStrategy() {
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Object* pitcher = fBall.spd.fX > 0 ? &fPaddle0 : &fPaddle1;
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Object* catcher = fBall.spd.fX > 0 ? &fPaddle1 : &fPaddle0;
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SkScalar t, yIntercept;
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std::tie(t, yIntercept) = find_yintercept(fBall.pos, fBall.spd, kBounds);
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// The pitcher aims for a neutral/centered position.
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pitcher->spd.fY = (kBounds.centerY() - pitcher->pos.fY) / t;
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// The catcher goes for the ball. Duh.
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catcher->spd.fY = (yIntercept - catcher->pos.fY) / t;
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}
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sk_sp<SkSVGDOM> fDom;
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Object fPaddle0, fPaddle1, fBall;
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SkRandom fRand;
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SkMSec fLastTick = 0;
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SkScalar fTimeScale = 1.0f;
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typedef SampleView INHERITED;
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};
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static SkView* SVGPongFactory() { return new SVGPongView; }
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static SkViewRegister reg(SVGPongFactory);
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