samplecode/Sample3D.cpp - platform/external/skia - Gitiles

 /*
  * Copyright 2020 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "include/core/SkCanvas.h"
 #include "include/core/SkM44.h"
 #include "include/core/SkPaint.h"
 #include "include/core/SkRRect.h"
 #include "include/core/SkVertices.h"
 #include "include/utils/SkRandom.h"
 #include "samplecode/Sample.h"
 #include "tools/Resources.h"

 struct VSphere {
     SkV2     fCenter;
     SkScalar fRadius;

     VSphere(SkV2 center, SkScalar radius) : fCenter(center), fRadius(radius) {}

     bool contains(SkV2 v) const {
         return (v - fCenter).length() <= fRadius;
     }

     SkV2 pinLoc(SkV2 p) const {
         auto v = p - fCenter;
         if (v.length() > fRadius) {
             v *= (fRadius / v.length());
         }
         return fCenter + v;
     }

     SkV3 computeUnitV3(SkV2 v) const {
         v = (v - fCenter) * (1 / fRadius);
         SkScalar len2 = v.lengthSquared();
         if (len2 > 1) {
             v = v.normalize();
             len2 = 1;
         }
         SkScalar z = SkScalarSqrt(1 - len2);
         return {v.x, v.y, z};
     }

     struct RotateInfo {
         SkV3    fAxis;
         SkScalar fAngle;
     };

     RotateInfo computeRotationInfo(SkV2 a, SkV2 b) const {
         SkV3 u = this->computeUnitV3(a);
         SkV3 v = this->computeUnitV3(b);
         SkV3 axis = u.cross(v);
         SkScalar length = axis.length();

         if (!SkScalarNearlyZero(length)) {
             return {axis * (1.0f / length), acos(u.dot(v))};
         }
         return {{0, 0, 0}, 0};
     }

     SkM44 computeRotation(SkV2 a, SkV2 b) const {
         auto [axis, angle] = this->computeRotationInfo(a, b);
         return SkM44::Rotate(axis, angle);
     }
 };

 static SkM44 inv(const SkM44& m) {
     SkM44 inverse;
     SkAssertResult(m.invert(&inverse));
     return inverse;
 }

 class Sample3DView : public Sample {
 protected:
     float   fNear = 0.05f;
     float   fFar = 4;
     float   fAngle = SK_ScalarPI / 12;

     SkV3    fEye { 0, 0, 1.0f/tan(fAngle/2) - 1 };
     SkV3    fCOA { 0, 0, 0 };
     SkV3    fUp  { 0, 1, 0 };

     const char* kLocalToWorld = "local_to_world";

 public:
     void concatCamera(SkCanvas* canvas, const SkRect& area, SkScalar zscale) {
         SkM44 camera = Sk3LookAt(fEye, fCOA, fUp),
               perspective = Sk3Perspective(fNear, fFar, fAngle),
               viewport = SkM44::Translate(area.centerX(), area.centerY(), 0) *
                          SkM44::Scale(area.width()*0.5f, area.height()*0.5f, zscale);

         canvas->concat(viewport * perspective * camera * inv(viewport));
     }
 };

 struct Face {
     SkScalar fRx, fRy;
     SkColor  fColor;

     static SkM44 T(SkScalar x, SkScalar y, SkScalar z) {
         return SkM44::Translate(x, y, z);
     }

     static SkM44 R(SkV3 axis, SkScalar rad) {
         return SkM44::Rotate(axis, rad);
     }

     SkM44 asM44(SkScalar scale) const {
         return R({0,1,0}, fRy) * R({1,0,0}, fRx) * T(0, 0, scale);
     }
 };

 static bool front(const SkM44& m) {
     SkM44 m2(SkM44::kUninitialized_Constructor);
     if (!m.invert(&m2)) {
         m2.setIdentity();
     }
     /*
      *  Classically we want to dot the transpose(inverse(ctm)) with our surface normal.
      *  In this case, the normal is known to be {0, 0, 1}, so we only actually need to look
      *  at the z-scale of the inverse (the transpose doesn't change the main diagonal, so
      *  no need to actually transpose).
      */
     return m2.rc(2,2) > 0;
 }

 const Face faces[] = {
     {             0,             0,  SK_ColorRED }, // front
     {             0,   SK_ScalarPI,  SK_ColorGREEN }, // back

     { SK_ScalarPI/2,             0,  SK_ColorBLUE }, // top
     {-SK_ScalarPI/2,             0,  SK_ColorCYAN }, // bottom

     {             0, SK_ScalarPI/2,  SK_ColorMAGENTA }, // left
     {             0,-SK_ScalarPI/2,  SK_ColorYELLOW }, // right
 };

 #include "include/effects/SkRuntimeEffect.h"

 struct LightOnSphere {
     SkV2     fLoc;
     SkScalar fDistance;
     SkScalar fRadius;

     SkV3 computeWorldPos(const VSphere& s) const {
         return s.computeUnitV3(fLoc) * fDistance;
     }

     void draw(SkCanvas* canvas) const {
         SkPaint paint;
         paint.setAntiAlias(true);
         paint.setColor(SK_ColorWHITE);
         canvas->drawCircle(fLoc.x, fLoc.y, fRadius + 2, paint);
         paint.setColor(SK_ColorBLACK);
         canvas->drawCircle(fLoc.x, fLoc.y, fRadius, paint);
     }
 };

 #include "include/core/SkTime.h"

 class RotateAnimator {
     SkV3        fAxis = {0, 0, 0};
     SkScalar    fAngle = 0,
                 fPrevAngle = 1234567;
     double      fNow = 0,
                 fPrevNow = 0;

     SkScalar    fAngleSpeed = 0,
                 fAngleSign = 1;

     static constexpr double kSlowDown = 4;
     static constexpr SkScalar kMaxSpeed = 16;

 public:
     void update(SkV3 axis, SkScalar angle) {
         if (angle != fPrevAngle) {
             fPrevAngle = fAngle;
             fAngle = angle;

             fPrevNow = fNow;
             fNow = SkTime::GetSecs();

             fAxis = axis;
         }
     }

     SkM44 rotation() {
         if (fAngleSpeed > 0) {
             double now = SkTime::GetSecs();
             double dtime = now - fPrevNow;
             fPrevNow = now;
             double delta = fAngleSign * fAngleSpeed * dtime;
             fAngle += delta;
             fAngleSpeed -= kSlowDown * dtime;
             if (fAngleSpeed < 0) {
                 fAngleSpeed = 0;
             }
         }
         return SkM44::Rotate(fAxis, fAngle);

     }

     void start() {
         if (fPrevNow != fNow) {
             fAngleSpeed = (fAngle - fPrevAngle) / (fNow - fPrevNow);
             fAngleSign = fAngleSpeed < 0 ? -1 : 1;
             fAngleSpeed = std::min(kMaxSpeed, std::abs(fAngleSpeed));
         } else {
             fAngleSpeed = 0;
         }
         fPrevNow = SkTime::GetSecs();
         fAngle = 0;
     }

     void reset() {
         fAngleSpeed = 0;
         fAngle = 0;
         fPrevAngle = 1234567;
     }

     bool isAnimating() const { return fAngleSpeed != 0; }
 };

 class SampleCubeBase : public Sample3DView {
     enum {
         DX = 400,
         DY = 300
     };

     SkM44 fRotation;        // part of model

     RotateAnimator fRotateAnimator;

 protected:
     enum Flags {
         kCanRunOnCPU    = 1 << 0,
         kShowLightDome  = 1 << 1,
     };

     LightOnSphere fLight = {{200 + DX, 200 + DY}, 800, 12};

     VSphere fSphere;
     Flags   fFlags;

 public:
     SampleCubeBase(Flags flags)
         : fSphere({200 + DX, 200 + DY}, 400)
         , fFlags(flags)
     {}

     bool onChar(SkUnichar uni) override {
         switch (uni) {
             case 'Z': fLight.fDistance += 10; return true;
             case 'z': fLight.fDistance -= 10; return true;
         }
         return this->Sample3DView::onChar(uni);
     }

     virtual void drawContent(SkCanvas* canvas, SkColor, int index, bool drawFront) = 0;

     void onDrawContent(SkCanvas* canvas) override {
         if (!canvas->recordingContext() && !(fFlags & kCanRunOnCPU)) {
             return;
         }

         canvas->save();
         canvas->translate(DX, DY);

         this->concatCamera(canvas, {0, 0, 400, 400}, 200);

         for (bool drawFront : {false, true}) {
             int index = 0;
             for (auto f : faces) {
                 SkAutoCanvasRestore acr(canvas, true);

                 SkM44 trans = SkM44::Translate(200, 200, 0);   // center of the rotation
                 SkM44 m = fRotateAnimator.rotation() * fRotation * f.asM44(200);

                 canvas->concat(trans);

                 // "World" space - content is centered at the origin, in device scale (+-200)
                 canvas->markCTM(kLocalToWorld);

                 canvas->concat(m * inv(trans));
                 this->drawContent(canvas, f.fColor, index++, drawFront);
             }
         }

         canvas->restore();  // camera & center the content in the window

         if (fFlags & kShowLightDome){
             fLight.draw(canvas);

             SkPaint paint;
             paint.setAntiAlias(true);
             paint.setStyle(SkPaint::kStroke_Style);
             paint.setColor(0x40FF0000);
             canvas->drawCircle(fSphere.fCenter.x, fSphere.fCenter.y, fSphere.fRadius, paint);
             canvas->drawLine(fSphere.fCenter.x, fSphere.fCenter.y - fSphere.fRadius,
                              fSphere.fCenter.x, fSphere.fCenter.y + fSphere.fRadius, paint);
             canvas->drawLine(fSphere.fCenter.x - fSphere.fRadius, fSphere.fCenter.y,
                              fSphere.fCenter.x + fSphere.fRadius, fSphere.fCenter.y, paint);
         }
     }

     Click* onFindClickHandler(SkScalar x, SkScalar y, skui::ModifierKey modi) override {
         SkV2 p = fLight.fLoc - SkV2{x, y};
         if (p.length() <= fLight.fRadius) {
             Click* c = new Click();
             c->fMeta.setS32("type", 0);
             return c;
         }
         if (fSphere.contains({x, y})) {
             Click* c = new Click();
             c->fMeta.setS32("type", 1);

             fRotation = fRotateAnimator.rotation() * fRotation;
             fRotateAnimator.reset();
             return c;
         }
         return nullptr;
     }
     bool onClick(Click* click) override {
         if (click->fMeta.hasS32("type", 0)) {
             fLight.fLoc = fSphere.pinLoc({click->fCurr.fX, click->fCurr.fY});
             return true;
         }
         if (click->fMeta.hasS32("type", 1)) {
             if (click->fState == skui::InputState::kUp) {
                 fRotation = fRotateAnimator.rotation() * fRotation;
                 fRotateAnimator.start();
             } else {
                 auto [axis, angle] = fSphere.computeRotationInfo(
                                                 {click->fOrig.fX, click->fOrig.fY},
                                                 {click->fCurr.fX, click->fCurr.fY});
                 fRotateAnimator.update(axis, angle);
             }
             return true;
         }
         return true;
     }

     bool onAnimate(double nanos) override {
         return fRotateAnimator.isAnimating();
     }

 private:
     typedef Sample3DView INHERITED;
 };

 class SampleBump3D : public SampleCubeBase {
     sk_sp<SkShader>        fBmpShader, fImgShader;
     sk_sp<SkRuntimeEffect> fEffect;
     SkRRect                fRR;

 public:
     SampleBump3D() : SampleCubeBase(Flags(kCanRunOnCPU | kShowLightDome)) {}

     SkString name() override { return SkString("bump3d"); }

     void onOnceBeforeDraw() override {
         fRR = SkRRect::MakeRectXY({20, 20, 380, 380}, 50, 50);
         auto img = GetResourceAsImage("images/brickwork-texture.jpg");
         fImgShader = img->makeShader(SkMatrix::Scale(2, 2));
         img = GetResourceAsImage("images/brickwork_normal-map.jpg");
         fBmpShader = img->makeShader(SkMatrix::Scale(2, 2));

         const char code[] = R"(
             in shader color_map;
             in shader normal_map;

             layout (marker=local_to_world)          uniform float4x4 localToWorld;
             layout (marker=normals(local_to_world)) uniform float4x4 localToWorldAdjInv;
             uniform float3   lightPos;

             float3 convert_normal_sample(half4 c) {
                 float3 n = 2 * c.rgb - 1;
                 n.y = -n.y;
                 return n;
             }

             void main(float2 p, inout half4 color) {
                 float3 norm = convert_normal_sample(sample(normal_map, p));
                 float3 plane_norm = normalize(localToWorldAdjInv * float4(norm, 0)).xyz;

                 float3 plane_pos = (localToWorld * float4(p, 0, 1)).xyz;
                 float3 light_dir = normalize(lightPos - plane_pos);

                 float ambient = 0.2;
                 float dp = dot(plane_norm, light_dir);
                 float scale = min(ambient + max(dp, 0), 1);

                 color = sample(color_map, p) * half4(float4(scale, scale, scale, 1));
             }
         )";
         auto [effect, error] = SkRuntimeEffect::Make(SkString(code));
         if (!effect) {
             SkDebugf("runtime error %s\n", error.c_str());
         }
         fEffect = effect;
     }

     void drawContent(SkCanvas* canvas, SkColor color, int index, bool drawFront) override {
         if (!drawFront || !front(canvas->getLocalToDevice())) {
             return;
         }

         SkRuntimeShaderBuilder builder(fEffect);
         builder.uniform("lightPos") = fLight.computeWorldPos(fSphere);
         // localToWorld matrices are automatically populated, via layout(marker)

         builder.child("color_map")  = fImgShader;
         builder.child("normal_map") = fBmpShader;

         SkPaint paint;
         paint.setColor(color);
         paint.setShader(builder.makeShader(nullptr, true));

         canvas->drawRRect(fRR, paint);
     }
 };
 DEF_SAMPLE( return new SampleBump3D; )

 class SampleVerts3D : public SampleCubeBase {
     sk_sp<SkRuntimeEffect> fEffect;
     sk_sp<SkVertices>      fVertices;

 public:
     SampleVerts3D() : SampleCubeBase(kShowLightDome) {}

     SkString name() override { return SkString("verts3d"); }

     void onOnceBeforeDraw() override {
         using Attr = SkVertices::Attribute;
         Attr attrs[] = {
             Attr(Attr::Type::kFloat3, Attr::Usage::kNormalVector),
         };

         SkVertices::Builder builder(SkVertices::kTriangleFan_VertexMode, 66, 0, attrs, 1);

         SkPoint* pos = builder.positions();
         SkV3* nrm = (SkV3*)builder.customData();

         SkPoint center = { 200, 200 };
         SkScalar radius = 200;

         pos[0] = center;
         nrm[0] = { 0, 0, 1 };

         for (int i = 0; i < 65; ++i) {
             SkScalar t = (i / 64.0f) * 2 * SK_ScalarPI;
             SkScalar s = SkScalarSin(t),
                      c = SkScalarCos(t);
             pos[i + 1] = center + SkPoint { c * radius, s * radius };
             nrm[i + 1] = { c, s, 0 };
         }

         fVertices = builder.detach();

         const char code[] = R"(
             varying float3 vtx_normal;

             layout (marker=local_to_world)          uniform float4x4 localToWorld;
             layout (marker=normals(local_to_world)) uniform float4x4 localToWorldAdjInv;
             uniform float3   lightPos;

             void main(float2 p, inout half4 color) {
                 float3 norm = normalize(vtx_normal);
                 float3 plane_norm = normalize(localToWorldAdjInv * float4(norm, 0)).xyz;

                 float3 plane_pos = (localToWorld * float4(p, 0, 1)).xyz;
                 float3 light_dir = normalize(lightPos - plane_pos);

                 float ambient = 0.2;
                 float dp = dot(plane_norm, light_dir);
                 float scale = min(ambient + max(dp, 0), 1);

                 color = half4(0.7, 0.9, 0.3, 1) * half4(float4(scale, scale, scale, 1));
             }
         )";
         auto [effect, error] = SkRuntimeEffect::Make(SkString(code));
         if (!effect) {
             SkDebugf("runtime error %s\n", error.c_str());
         }
         fEffect = effect;
     }

     void drawContent(SkCanvas* canvas, SkColor color, int index, bool drawFront) override {
         if (!drawFront || !front(canvas->getLocalToDevice())) {
             return;
         }

         SkRuntimeShaderBuilder builder(fEffect);
         builder.uniform("lightPos") = fLight.computeWorldPos(fSphere);

         SkPaint paint;
         paint.setColor(color);
         paint.setShader(builder.makeShader(nullptr, true));

         canvas->drawVertices(fVertices, paint);
     }
 };
 DEF_SAMPLE( return new SampleVerts3D; )

 #include "modules/skottie/include/Skottie.h"

 class SampleSkottieCube : public SampleCubeBase {
     sk_sp<skottie::Animation> fAnim[6];

 public:
     SampleSkottieCube() : SampleCubeBase(kCanRunOnCPU) {}

     SkString name() override { return SkString("skottie3d"); }

     void onOnceBeforeDraw() override {
         const char* files[] = {
             "skottie/skottie-chained-mattes.json",
             "skottie/skottie-gradient-ramp.json",
             "skottie/skottie_sample_2.json",
             "skottie/skottie-3d-3planes.json",
             "skottie/skottie-text-animator-4.json",
             "skottie/skottie-motiontile-effect-phase.json",

         };
         for (unsigned i = 0; i < SK_ARRAY_COUNT(files); ++i) {
             if (auto stream = GetResourceAsStream(files[i])) {
                 fAnim[i] = skottie::Animation::Make(stream.get());
             }
         }
     }

     void drawContent(SkCanvas* canvas, SkColor color, int index, bool drawFront) override {
         if (!drawFront || !front(canvas->getLocalToDevice())) {
             return;
         }

         SkPaint paint;
         paint.setColor(color);
         SkRect r = {0, 0, 400, 400};
         canvas->drawRect(r, paint);
         fAnim[index]->render(canvas, &r);
     }

     bool onAnimate(double nanos) override {
         for (auto& anim : fAnim) {
             SkScalar dur = anim->duration();
             SkScalar t = fmod(1e-9 * nanos, dur) / dur;
             anim->seek(t);
         }
         return true;
     }
 };
 DEF_SAMPLE( return new SampleSkottieCube; )
	/*
	* Copyright 2020 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "include/core/SkCanvas.h"
	#include "include/core/SkM44.h"
	#include "include/core/SkPaint.h"
	#include "include/core/SkRRect.h"
	#include "include/core/SkVertices.h"
	#include "include/utils/SkRandom.h"
	#include "samplecode/Sample.h"
	#include "tools/Resources.h"

	struct VSphere {
	SkV2 fCenter;
	SkScalar fRadius;

	VSphere(SkV2 center, SkScalar radius) : fCenter(center), fRadius(radius) {}

	bool contains(SkV2 v) const {
	return (v - fCenter).length() <= fRadius;
	}

	SkV2 pinLoc(SkV2 p) const {
	auto v = p - fCenter;
	if (v.length() > fRadius) {
	v *= (fRadius / v.length());
	}
	return fCenter + v;
	}

	SkV3 computeUnitV3(SkV2 v) const {
	v = (v - fCenter) * (1 / fRadius);
	SkScalar len2 = v.lengthSquared();
	if (len2 > 1) {
	v = v.normalize();
	len2 = 1;
	}
	SkScalar z = SkScalarSqrt(1 - len2);
	return {v.x, v.y, z};
	}

	struct RotateInfo {
	SkV3 fAxis;
	SkScalar fAngle;
	};

	RotateInfo computeRotationInfo(SkV2 a, SkV2 b) const {
	SkV3 u = this->computeUnitV3(a);
	SkV3 v = this->computeUnitV3(b);
	SkV3 axis = u.cross(v);
	SkScalar length = axis.length();

	if (!SkScalarNearlyZero(length)) {
	return {axis * (1.0f / length), acos(u.dot(v))};
	}
	return {{0, 0, 0}, 0};
	}

	SkM44 computeRotation(SkV2 a, SkV2 b) const {
	auto [axis, angle] = this->computeRotationInfo(a, b);
	return SkM44::Rotate(axis, angle);
	}
	};

	static SkM44 inv(const SkM44& m) {
	SkM44 inverse;
	SkAssertResult(m.invert(&inverse));
	return inverse;
	}

	class Sample3DView : public Sample {
	protected:
	float fNear = 0.05f;
	float fFar = 4;
	float fAngle = SK_ScalarPI / 12;

	SkV3 fEye { 0, 0, 1.0f/tan(fAngle/2) - 1 };
	SkV3 fCOA { 0, 0, 0 };
	SkV3 fUp { 0, 1, 0 };

	const char* kLocalToWorld = "local_to_world";

	public:
	void concatCamera(SkCanvas* canvas, const SkRect& area, SkScalar zscale) {
	SkM44 camera = Sk3LookAt(fEye, fCOA, fUp),
	perspective = Sk3Perspective(fNear, fFar, fAngle),
	viewport = SkM44::Translate(area.centerX(), area.centerY(), 0) *
	SkM44::Scale(area.width()0.5f, area.height()0.5f, zscale);

	canvas->concat(viewport * perspective * camera * inv(viewport));
	}
	};

	struct Face {
	SkScalar fRx, fRy;
	SkColor fColor;

	static SkM44 T(SkScalar x, SkScalar y, SkScalar z) {
	return SkM44::Translate(x, y, z);
	}

	static SkM44 R(SkV3 axis, SkScalar rad) {
	return SkM44::Rotate(axis, rad);
	}

	SkM44 asM44(SkScalar scale) const {
	return R({0,1,0}, fRy) * R({1,0,0}, fRx) * T(0, 0, scale);
	}
	};

	static bool front(const SkM44& m) {
	SkM44 m2(SkM44::kUninitialized_Constructor);
	if (!m.invert(&m2)) {
	m2.setIdentity();
	}
	/*
	* Classically we want to dot the transpose(inverse(ctm)) with our surface normal.
	* In this case, the normal is known to be {0, 0, 1}, so we only actually need to look
	* at the z-scale of the inverse (the transpose doesn't change the main diagonal, so
	* no need to actually transpose).
	*/
	return m2.rc(2,2) > 0;
	}

	const Face faces[] = {
	{ 0, 0, SK_ColorRED }, // front
	{ 0, SK_ScalarPI, SK_ColorGREEN }, // back

	{ SK_ScalarPI/2, 0, SK_ColorBLUE }, // top
	{-SK_ScalarPI/2, 0, SK_ColorCYAN }, // bottom

	{ 0, SK_ScalarPI/2, SK_ColorMAGENTA }, // left
	{ 0,-SK_ScalarPI/2, SK_ColorYELLOW }, // right
	};

	#include "include/effects/SkRuntimeEffect.h"

	struct LightOnSphere {
	SkV2 fLoc;
	SkScalar fDistance;
	SkScalar fRadius;

	SkV3 computeWorldPos(const VSphere& s) const {
	return s.computeUnitV3(fLoc) * fDistance;
	}

	void draw(SkCanvas* canvas) const {
	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setColor(SK_ColorWHITE);
	canvas->drawCircle(fLoc.x, fLoc.y, fRadius + 2, paint);
	paint.setColor(SK_ColorBLACK);
	canvas->drawCircle(fLoc.x, fLoc.y, fRadius, paint);
	}
	};

	#include "include/core/SkTime.h"

	class RotateAnimator {
	SkV3 fAxis = {0, 0, 0};
	SkScalar fAngle = 0,
	fPrevAngle = 1234567;
	double fNow = 0,
	fPrevNow = 0;

	SkScalar fAngleSpeed = 0,
	fAngleSign = 1;

	static constexpr double kSlowDown = 4;
	static constexpr SkScalar kMaxSpeed = 16;

	public:
	void update(SkV3 axis, SkScalar angle) {
	if (angle != fPrevAngle) {
	fPrevAngle = fAngle;
	fAngle = angle;

	fPrevNow = fNow;
	fNow = SkTime::GetSecs();

	fAxis = axis;
	}
	}

	SkM44 rotation() {
	if (fAngleSpeed > 0) {
	double now = SkTime::GetSecs();
	double dtime = now - fPrevNow;
	fPrevNow = now;
	double delta = fAngleSign * fAngleSpeed * dtime;
	fAngle += delta;
	fAngleSpeed -= kSlowDown * dtime;
	if (fAngleSpeed < 0) {
	fAngleSpeed = 0;
	}
	}
	return SkM44::Rotate(fAxis, fAngle);

	}

	void start() {
	if (fPrevNow != fNow) {
	fAngleSpeed = (fAngle - fPrevAngle) / (fNow - fPrevNow);
	fAngleSign = fAngleSpeed < 0 ? -1 : 1;
	fAngleSpeed = std::min(kMaxSpeed, std::abs(fAngleSpeed));
	} else {
	fAngleSpeed = 0;
	}
	fPrevNow = SkTime::GetSecs();
	fAngle = 0;
	}

	void reset() {
	fAngleSpeed = 0;
	fAngle = 0;
	fPrevAngle = 1234567;
	}

	bool isAnimating() const { return fAngleSpeed != 0; }
	};

	class SampleCubeBase : public Sample3DView {
	enum {
	DX = 400,
	DY = 300
	};

	SkM44 fRotation; // part of model

	RotateAnimator fRotateAnimator;

	protected:
	enum Flags {
	kCanRunOnCPU = 1 << 0,
	kShowLightDome = 1 << 1,
	};

	LightOnSphere fLight = {{200 + DX, 200 + DY}, 800, 12};

	VSphere fSphere;
	Flags fFlags;

	public:
	SampleCubeBase(Flags flags)
	: fSphere({200 + DX, 200 + DY}, 400)
	, fFlags(flags)
	{}

	bool onChar(SkUnichar uni) override {
	switch (uni) {
	case 'Z': fLight.fDistance += 10; return true;
	case 'z': fLight.fDistance -= 10; return true;
	}
	return this->Sample3DView::onChar(uni);
	}

	virtual void drawContent(SkCanvas* canvas, SkColor, int index, bool drawFront) = 0;

	void onDrawContent(SkCanvas* canvas) override {
	if (!canvas->recordingContext() && !(fFlags & kCanRunOnCPU)) {
	return;
	}

	canvas->save();
	canvas->translate(DX, DY);

	this->concatCamera(canvas, {0, 0, 400, 400}, 200);

	for (bool drawFront : {false, true}) {
	int index = 0;
	for (auto f : faces) {
	SkAutoCanvasRestore acr(canvas, true);

	SkM44 trans = SkM44::Translate(200, 200, 0); // center of the rotation
	SkM44 m = fRotateAnimator.rotation() * fRotation * f.asM44(200);

	canvas->concat(trans);

	// "World" space - content is centered at the origin, in device scale (+-200)
	canvas->markCTM(kLocalToWorld);

	canvas->concat(m * inv(trans));
	this->drawContent(canvas, f.fColor, index++, drawFront);
	}
	}

	canvas->restore(); // camera & center the content in the window

	if (fFlags & kShowLightDome){
	fLight.draw(canvas);

	SkPaint paint;
	paint.setAntiAlias(true);
	paint.setStyle(SkPaint::kStroke_Style);
	paint.setColor(0x40FF0000);
	canvas->drawCircle(fSphere.fCenter.x, fSphere.fCenter.y, fSphere.fRadius, paint);
	canvas->drawLine(fSphere.fCenter.x, fSphere.fCenter.y - fSphere.fRadius,
	fSphere.fCenter.x, fSphere.fCenter.y + fSphere.fRadius, paint);
	canvas->drawLine(fSphere.fCenter.x - fSphere.fRadius, fSphere.fCenter.y,
	fSphere.fCenter.x + fSphere.fRadius, fSphere.fCenter.y, paint);
	}
	}

	Click* onFindClickHandler(SkScalar x, SkScalar y, skui::ModifierKey modi) override {
	SkV2 p = fLight.fLoc - SkV2{x, y};
	if (p.length() <= fLight.fRadius) {
	Click* c = new Click();
	c->fMeta.setS32("type", 0);
	return c;
	}
	if (fSphere.contains({x, y})) {
	Click* c = new Click();
	c->fMeta.setS32("type", 1);

	fRotation = fRotateAnimator.rotation() * fRotation;
	fRotateAnimator.reset();
	return c;
	}
	return nullptr;
	}
	bool onClick(Click* click) override {
	if (click->fMeta.hasS32("type", 0)) {
	fLight.fLoc = fSphere.pinLoc({click->fCurr.fX, click->fCurr.fY});
	return true;
	}
	if (click->fMeta.hasS32("type", 1)) {
	if (click->fState == skui::InputState::kUp) {
	fRotation = fRotateAnimator.rotation() * fRotation;
	fRotateAnimator.start();
	} else {
	auto [axis, angle] = fSphere.computeRotationInfo(
	{click->fOrig.fX, click->fOrig.fY},
	{click->fCurr.fX, click->fCurr.fY});
	fRotateAnimator.update(axis, angle);
	}
	return true;
	}
	return true;
	}

	bool onAnimate(double nanos) override {
	return fRotateAnimator.isAnimating();
	}

	private:
	typedef Sample3DView INHERITED;
	};

	class SampleBump3D : public SampleCubeBase {
	sk_sp<SkShader> fBmpShader, fImgShader;
	sk_sp<SkRuntimeEffect> fEffect;
	SkRRect fRR;

	public:
	SampleBump3D() : SampleCubeBase(Flags(kCanRunOnCPU \| kShowLightDome)) {}

	SkString name() override { return SkString("bump3d"); }

	void onOnceBeforeDraw() override {
	fRR = SkRRect::MakeRectXY({20, 20, 380, 380}, 50, 50);
	auto img = GetResourceAsImage("images/brickwork-texture.jpg");
	fImgShader = img->makeShader(SkMatrix::Scale(2, 2));
	img = GetResourceAsImage("images/brickwork_normal-map.jpg");
	fBmpShader = img->makeShader(SkMatrix::Scale(2, 2));

	const char code[] = R"(
	in shader color_map;
	in shader normal_map;

	layout (marker=local_to_world) uniform float4x4 localToWorld;
	layout (marker=normals(local_to_world)) uniform float4x4 localToWorldAdjInv;
	uniform float3 lightPos;

	float3 convert_normal_sample(half4 c) {
	float3 n = 2 * c.rgb - 1;
	n.y = -n.y;
	return n;
	}

	void main(float2 p, inout half4 color) {
	float3 norm = convert_normal_sample(sample(normal_map, p));
	float3 plane_norm = normalize(localToWorldAdjInv * float4(norm, 0)).xyz;

	float3 plane_pos = (localToWorld * float4(p, 0, 1)).xyz;
	float3 light_dir = normalize(lightPos - plane_pos);

	float ambient = 0.2;
	float dp = dot(plane_norm, light_dir);
	float scale = min(ambient + max(dp, 0), 1);

	color = sample(color_map, p) * half4(float4(scale, scale, scale, 1));
	}
	)";
	auto [effect, error] = SkRuntimeEffect::Make(SkString(code));
	if (!effect) {
	SkDebugf("runtime error %s\n", error.c_str());
	}
	fEffect = effect;
	}

	void drawContent(SkCanvas* canvas, SkColor color, int index, bool drawFront) override {
	if (!drawFront \|\| !front(canvas->getLocalToDevice())) {
	return;
	}

	SkRuntimeShaderBuilder builder(fEffect);
	builder.uniform("lightPos") = fLight.computeWorldPos(fSphere);
	// localToWorld matrices are automatically populated, via layout(marker)

	builder.child("color_map") = fImgShader;
	builder.child("normal_map") = fBmpShader;

	SkPaint paint;
	paint.setColor(color);
	paint.setShader(builder.makeShader(nullptr, true));

	canvas->drawRRect(fRR, paint);
	}
	};
	DEF_SAMPLE( return new SampleBump3D; )

	class SampleVerts3D : public SampleCubeBase {
	sk_sp<SkRuntimeEffect> fEffect;
	sk_sp<SkVertices> fVertices;

	public:
	SampleVerts3D() : SampleCubeBase(kShowLightDome) {}

	SkString name() override { return SkString("verts3d"); }

	void onOnceBeforeDraw() override {
	using Attr = SkVertices::Attribute;
	Attr attrs[] = {
	Attr(Attr::Type::kFloat3, Attr::Usage::kNormalVector),
	};

	SkVertices::Builder builder(SkVertices::kTriangleFan_VertexMode, 66, 0, attrs, 1);

	SkPoint* pos = builder.positions();
	SkV3* nrm = (SkV3*)builder.customData();

	SkPoint center = { 200, 200 };
	SkScalar radius = 200;

	pos[0] = center;
	nrm[0] = { 0, 0, 1 };

	for (int i = 0; i < 65; ++i) {
	SkScalar t = (i / 64.0f) * 2 * SK_ScalarPI;
	SkScalar s = SkScalarSin(t),
	c = SkScalarCos(t);
	pos[i + 1] = center + SkPoint { c * radius, s * radius };
	nrm[i + 1] = { c, s, 0 };
	}

	fVertices = builder.detach();

	const char code[] = R"(
	varying float3 vtx_normal;

	layout (marker=local_to_world) uniform float4x4 localToWorld;
	layout (marker=normals(local_to_world)) uniform float4x4 localToWorldAdjInv;
	uniform float3 lightPos;

	void main(float2 p, inout half4 color) {
	float3 norm = normalize(vtx_normal);
	float3 plane_norm = normalize(localToWorldAdjInv * float4(norm, 0)).xyz;

	float3 plane_pos = (localToWorld * float4(p, 0, 1)).xyz;
	float3 light_dir = normalize(lightPos - plane_pos);

	float ambient = 0.2;
	float dp = dot(plane_norm, light_dir);
	float scale = min(ambient + max(dp, 0), 1);

	color = half4(0.7, 0.9, 0.3, 1) * half4(float4(scale, scale, scale, 1));
	}
	)";
	auto [effect, error] = SkRuntimeEffect::Make(SkString(code));
	if (!effect) {
	SkDebugf("runtime error %s\n", error.c_str());
	}
	fEffect = effect;
	}

	void drawContent(SkCanvas* canvas, SkColor color, int index, bool drawFront) override {
	if (!drawFront \|\| !front(canvas->getLocalToDevice())) {
	return;
	}

	SkRuntimeShaderBuilder builder(fEffect);
	builder.uniform("lightPos") = fLight.computeWorldPos(fSphere);

	SkPaint paint;
	paint.setColor(color);
	paint.setShader(builder.makeShader(nullptr, true));

	canvas->drawVertices(fVertices, paint);
	}
	};
	DEF_SAMPLE( return new SampleVerts3D; )

	#include "modules/skottie/include/Skottie.h"

	class SampleSkottieCube : public SampleCubeBase {
	sk_sp<skottie::Animation> fAnim[6];

	public:
	SampleSkottieCube() : SampleCubeBase(kCanRunOnCPU) {}

	SkString name() override { return SkString("skottie3d"); }

	void onOnceBeforeDraw() override {
	const char* files[] = {
	"skottie/skottie-chained-mattes.json",
	"skottie/skottie-gradient-ramp.json",
	"skottie/skottie_sample_2.json",
	"skottie/skottie-3d-3planes.json",
	"skottie/skottie-text-animator-4.json",
	"skottie/skottie-motiontile-effect-phase.json",

	};
	for (unsigned i = 0; i < SK_ARRAY_COUNT(files); ++i) {
	if (auto stream = GetResourceAsStream(files[i])) {
	fAnim[i] = skottie::Animation::Make(stream.get());
	}
	}
	}

	void drawContent(SkCanvas* canvas, SkColor color, int index, bool drawFront) override {
	if (!drawFront \|\| !front(canvas->getLocalToDevice())) {
	return;
	}

	SkPaint paint;
	paint.setColor(color);
	SkRect r = {0, 0, 400, 400};
	canvas->drawRect(r, paint);
	fAnim[index]->render(canvas, &r);
	}

	bool onAnimate(double nanos) override {
	for (auto& anim : fAnim) {
	SkScalar dur = anim->duration();
	SkScalar t = fmod(1e-9 * nanos, dur) / dur;
	anim->seek(t);
	}
	return true;
	}
	};
	DEF_SAMPLE( return new SampleSkottieCube; )