1 /*
2 * Copyright 2021 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include "modules/skottie/src/effects/Effects.h"
9
10 #include "include/core/SkM44.h"
11 #include "include/core/SkPictureRecorder.h"
12 #include "include/effects/SkRuntimeEffect.h"
13 #include "modules/skottie/src/Adapter.h"
14 #include "modules/skottie/src/SkottieJson.h"
15 #include "modules/skottie/src/SkottieValue.h"
16 #include "modules/sksg/include/SkSGRenderNode.h"
17
18 #include <array>
19
20 namespace skottie::internal {
21
22 namespace {
23
24 // This shader maps its child shader onto a sphere. To simplify things, we set it up such that:
25 //
26 // - the sphere is centered at origin and has r == 1
27 // - the eye is positioned at (0,0,eye_z), where eye_z is chosen to visually match AE
28 // - the POI for a given pixel is on the z = 0 plane (x,y,0)
29 // - we're only rendering inside the projected circle, which guarantees a quadratic solution
30 //
31 // Effect stages:
32 //
33 // 1) ray-cast to find the sphere intersection (selectable front/back solution);
34 // given the sphere geometry, this is also the normal
35 // 2) rotate the normal
36 // 3) UV-map the sphere
37 // 4) scale uv to source size and sample
38 // 5) apply lighting model
39 //
40 // Note: the current implementation uses two passes for two-side ("full") rendering, on the
41 // assumption that in practice most textures are opaque and two-side mode is infrequent;
42 // if this proves to be problematic, we could expand the implementation to blend both sides
43 // in one pass.
44 //
45 static constexpr char gSphereSkSL[] = R"(
46 uniform shader child;
47
48 uniform half3x3 rot_matrix;
49 uniform half2 child_scale;
50 uniform half side_select;
51
52 // apply_light()
53 %s
54
55 half3 to_sphere(half3 EYE) {
56 half eye_z2 = EYE.z*EYE.z;
57
58 half a = dot(EYE, EYE),
59 b = -2*eye_z2,
60 c = eye_z2 - 1,
61 t = (-b + side_select*sqrt(b*b - 4*a*c))/(2*a);
62
63 return half3(0, 0, -EYE.z) + EYE*t;
64 }
65
66 half4 main(float2 xy) {
67 half3 EYE = half3(xy, -5.5),
68 N = to_sphere(EYE),
69 RN = rot_matrix*N;
70
71 half kRPI = 1/3.1415927;
72
73 half2 UV = half2(
74 0.5 + kRPI * 0.5 * atan(RN.x, RN.z),
75 0.5 + kRPI * asin(RN.y)
76 );
77
78 return apply_light(EYE, N, sample(child, UV*child_scale));
79 }
80 )";
81
82 // CC Sphere uses a Phong-like lighting model:
83 //
84 // - "ambient" controls the intensity of the texture color
85 // - "diffuse" controls a multiplicative mix of texture and light color
86 // - "specular" controls a light color specular component
87 // - "roughness" is the specular exponent reciprocal
88 // - "light intensity" modulates the diffuse and specular components (but not ambient)
89 // - "light height" and "light direction" specify the light source position in spherical coords
90 //
91 // Implementation-wise, light intensity/height/direction are all combined into l_vec.
92 // For efficiency, we fall back to a stripped-down shader (ambient-only) when the diffuse & specular
93 // components are not used.
94 //
95 // TODO: "metal" and "reflective" parameters are ignored.
96 static constexpr char gBasicLightSkSL[] = R"(
97 uniform half l_coeff_ambient;
98
99 half4 apply_light(half3 EYE, half3 N, half4 c) {
100 c.rgb *= l_coeff_ambient;
101 return c;
102 }
103 )";
104
105 static constexpr char gFancyLightSkSL[] = R"(
106 uniform half3 l_vec;
107 uniform half3 l_color;
108 uniform half l_coeff_ambient;
109 uniform half l_coeff_diffuse;
110 uniform half l_coeff_specular;
111 uniform half l_specular_exp;
112
113 half4 apply_light(half3 EYE, half3 N, half4 c) {
114 half3 LR = reflect(-l_vec*side_select, N);
115 half s_base = max(dot(normalize(EYE), LR), 0),
116
117 a = l_coeff_ambient,
118 d = l_coeff_diffuse * max(dot(l_vec, N), 0),
119 s = l_coeff_specular * saturate(pow(s_base, l_specular_exp));
120
121 c.rgb = (a + d*l_color)*c.rgb + s*l_color;
122
123 return c;
124 }
125 )";
126
sphere_fancylight_effect()127 static sk_sp<SkRuntimeEffect> sphere_fancylight_effect() {
128 static const SkRuntimeEffect* effect =
129 SkRuntimeEffect::MakeForShader(SkStringPrintf(gSphereSkSL, gFancyLightSkSL), {})
130 .effect.release();
131 if (0 && !effect) {
132 printf("!!! %s\n",
133 SkRuntimeEffect::MakeForShader(SkStringPrintf(gSphereSkSL, gFancyLightSkSL), {})
134 .errorText.c_str());
135 }
136 SkASSERT(effect);
137
138 return sk_ref_sp(effect);
139 }
140
sphere_basiclight_effect()141 static sk_sp<SkRuntimeEffect> sphere_basiclight_effect() {
142 static const SkRuntimeEffect* effect =
143 SkRuntimeEffect::MakeForShader(SkStringPrintf(gSphereSkSL, gBasicLightSkSL), {})
144 .effect.release();
145 SkASSERT(effect);
146
147 return sk_ref_sp(effect);
148 }
149
150 class SphereNode final : public sksg::CustomRenderNode {
151 public:
SphereNode(sk_sp<RenderNode> child,const SkSize & child_size)152 SphereNode(sk_sp<RenderNode> child, const SkSize& child_size)
153 : INHERITED({std::move(child)})
154 , fChildSize(child_size) {}
155
156 enum class RenderSide {
157 kFull,
158 kOutside,
159 kInside,
160 };
161
162 SG_ATTRIBUTE(Center , SkPoint , fCenter)
163 SG_ATTRIBUTE(Radius , float , fRadius)
164 SG_ATTRIBUTE(Rotation, SkM44 , fRot )
165 SG_ATTRIBUTE(Side , RenderSide, fSide )
166
167 SG_ATTRIBUTE(LightVec , SkV3 , fLightVec )
168 SG_ATTRIBUTE(LightColor , SkV3 , fLightColor )
169 SG_ATTRIBUTE(AmbientLight , float, fAmbientLight )
170 SG_ATTRIBUTE(DiffuseLight , float, fDiffuseLight )
171 SG_ATTRIBUTE(SpecularLight, float, fSpecularLight)
172 SG_ATTRIBUTE(SpecularExp , float, fSpecularExp )
173
174 private:
contentShader()175 sk_sp<SkShader> contentShader() {
176 if (!fContentShader || this->hasChildrenInval()) {
177 const auto& child = this->children()[0];
178 child->revalidate(nullptr, SkMatrix::I());
179
180 SkPictureRecorder recorder;
181 child->render(recorder.beginRecording(SkRect::MakeSize(fChildSize)));
182
183 fContentShader = recorder.finishRecordingAsPicture()
184 ->makeShader(SkTileMode::kRepeat, SkTileMode::kRepeat, SkFilterMode::kLinear,
185 nullptr, nullptr);
186 }
187
188 return fContentShader;
189 }
190
buildEffectShader(float selector)191 sk_sp<SkShader> buildEffectShader(float selector) {
192 const auto has_fancy_light =
193 fLightVec.length() > 0 && (fDiffuseLight > 0 || fSpecularLight > 0);
194
195 SkRuntimeShaderBuilder builder(has_fancy_light
196 ? sphere_fancylight_effect()
197 : sphere_basiclight_effect());
198
199 builder.child ("child") = this->contentShader();
200 builder.uniform("child_scale") = fChildSize;
201 builder.uniform("side_select") = selector;
202 builder.uniform("rot_matrix") = std::array<float,9>{
203 fRot.rc(0,0), fRot.rc(0,1), fRot.rc(0,2),
204 fRot.rc(1,0), fRot.rc(1,1), fRot.rc(1,2),
205 fRot.rc(2,0), fRot.rc(2,1), fRot.rc(2,2),
206 };
207
208 builder.uniform("l_coeff_ambient") = fAmbientLight;
209
210 if (has_fancy_light) {
211 builder.uniform("l_vec") = fLightVec * -selector;
212 builder.uniform("l_color") = fLightColor;
213 builder.uniform("l_coeff_diffuse") = fDiffuseLight;
214 builder.uniform("l_coeff_specular") = fSpecularLight;
215 builder.uniform("l_specular_exp") = fSpecularExp;
216 }
217
218 const auto lm = SkMatrix::Translate(fCenter.fX, fCenter.fY) *
219 SkMatrix::Scale(fRadius, fRadius);
220
221 return builder.makeShader(&lm, false);
222 }
223
onRevalidate(sksg::InvalidationController * ic,const SkMatrix & ctm)224 SkRect onRevalidate(sksg::InvalidationController* ic, const SkMatrix& ctm) override {
225 fSphereShader.reset();
226 if (fSide != RenderSide::kOutside) {
227 fSphereShader = this->buildEffectShader(1);
228 }
229 if (fSide != RenderSide::kInside) {
230 auto outside = this->buildEffectShader(-1);
231 fSphereShader = fSphereShader
232 ? SkShaders::Blend(SkBlendMode::kSrcOver,
233 std::move(fSphereShader),
234 std::move(outside))
235 : std::move(outside);
236 }
237 SkASSERT(fSphereShader);
238
239 return SkRect::MakeLTRB(fCenter.fX - fRadius,
240 fCenter.fY - fRadius,
241 fCenter.fX + fRadius,
242 fCenter.fY + fRadius);
243 }
244
onRender(SkCanvas * canvas,const RenderContext * ctx) const245 void onRender(SkCanvas* canvas, const RenderContext* ctx) const override {
246 if (fRadius <= 0) {
247 return;
248 }
249
250 SkPaint sphere_paint;
251 sphere_paint.setAntiAlias(true);
252 sphere_paint.setShader(fSphereShader);
253
254 canvas->drawCircle(fCenter, fRadius, sphere_paint);
255 }
256
onNodeAt(const SkPoint &) const257 const RenderNode* onNodeAt(const SkPoint&) const override { return nullptr; } // no hit-testing
258
259 const SkSize fChildSize;
260
261 // Cached shaders
262 sk_sp<SkShader> fSphereShader;
263 sk_sp<SkShader> fContentShader;
264
265 // Effect controls.
266 SkM44 fRot;
267 SkPoint fCenter = {0,0};
268 float fRadius = 0;
269 RenderSide fSide = RenderSide::kFull;
270
271 SkV3 fLightVec = {0,0,1},
272 fLightColor = {1,1,1};
273 float fAmbientLight = 1,
274 fDiffuseLight = 0,
275 fSpecularLight = 0,
276 fSpecularExp = 0;
277
278 using INHERITED = sksg::CustomRenderNode;
279 };
280
281 class SphereAdapter final : public DiscardableAdapterBase<SphereAdapter, SphereNode> {
282 public:
SphereAdapter(const skjson::ArrayValue & jprops,const AnimationBuilder * abuilder,sk_sp<SphereNode> node)283 SphereAdapter(const skjson::ArrayValue& jprops,
284 const AnimationBuilder* abuilder,
285 sk_sp<SphereNode> node)
286 : INHERITED(std::move(node))
287 {
288 enum : size_t {
289 // kRotGrp_Index = 0,
290 kRotX_Index = 1,
291 kRotY_Index = 2,
292 kRotZ_Index = 3,
293 kRotOrder_Index = 4,
294 // ??? = 5,
295 kRadius_Index = 6,
296 kOffset_Index = 7,
297 kRender_Index = 8,
298
299 // kLight_Index = 9,
300 kLightIntensity_Index = 10,
301 kLightColor_Index = 11,
302 kLightHeight_Index = 12,
303 kLightDirection_Index = 13,
304 // ??? = 14,
305 // kShading_Index = 15,
306 kAmbient_Index = 16,
307 kDiffuse_Index = 17,
308 kSpecular_Index = 18,
309 kRoughness_Index = 19,
310 };
311
312 EffectBinder(jprops, *abuilder, this)
313 .bind( kOffset_Index, fOffset )
314 .bind( kRadius_Index, fRadius )
315 .bind( kRotX_Index, fRotX )
316 .bind( kRotY_Index, fRotY )
317 .bind( kRotZ_Index, fRotZ )
318 .bind(kRotOrder_Index, fRotOrder)
319 .bind( kRender_Index, fRender )
320
321 .bind(kLightIntensity_Index, fLightIntensity)
322 .bind( kLightColor_Index, fLightColor )
323 .bind( kLightHeight_Index, fLightHeight )
324 .bind(kLightDirection_Index, fLightDirection)
325 .bind( kAmbient_Index, fAmbient )
326 .bind( kDiffuse_Index, fDiffuse )
327 .bind( kSpecular_Index, fSpecular )
328 .bind( kRoughness_Index, fRoughness );
329 }
330
331 private:
onSync()332 void onSync() override {
333 const auto side = [](ScalarValue s) {
334 switch (SkScalarRoundToInt(s)) {
335 case 1: return SphereNode::RenderSide::kFull;
336 case 2: return SphereNode::RenderSide::kOutside;
337 case 3:
338 default: return SphereNode::RenderSide::kInside;
339 }
340 SkUNREACHABLE;
341 };
342
343 const auto rotation = [](ScalarValue order,
344 ScalarValue x, ScalarValue y, ScalarValue z) {
345 const SkM44 rx = SkM44::Rotate({1,0,0}, SkDegreesToRadians( x)),
346 ry = SkM44::Rotate({0,1,0}, SkDegreesToRadians( y)),
347 rz = SkM44::Rotate({0,0,1}, SkDegreesToRadians(-z));
348
349 switch (SkScalarRoundToInt(order)) {
350 case 1: return rx * ry * rz;
351 case 2: return rx * rz * ry;
352 case 3: return ry * rx * rz;
353 case 4: return ry * rz * rx;
354 case 5: return rz * rx * ry;
355 case 6:
356 default: return rz * ry * rx;
357 }
358 SkUNREACHABLE;
359 };
360
361 const auto light_vec = [](float height, float direction) {
362 float z = std::sin(height * SK_ScalarPI / 2),
363 r = std::sqrt(1 - z*z),
364 x = std::cos(direction) * r,
365 y = std::sin(direction) * r;
366
367 return SkV3{x,y,z};
368 };
369
370 const auto& sph = this->node();
371
372 sph->setCenter({fOffset.x, fOffset.y});
373 sph->setRadius(fRadius);
374 sph->setSide(side(fRender));
375 sph->setRotation(rotation(fRotOrder, fRotX, fRotY, fRotZ));
376
377 sph->setAmbientLight (SkTPin(fAmbient * 0.01f, 0.0f, 2.0f));
378
379 const auto intensity = SkTPin(fLightIntensity * 0.01f, 0.0f, 10.0f);
380 sph->setDiffuseLight (SkTPin(fDiffuse * 0.01f, 0.0f, 1.0f) * intensity);
381 sph->setSpecularLight(SkTPin(fSpecular* 0.01f, 0.0f, 1.0f) * intensity);
382
383 sph->setLightVec(light_vec(
384 SkTPin(fLightHeight * 0.01f, -1.0f, 1.0f),
385 SkDegreesToRadians(fLightDirection - 90)
386 ));
387
388 const auto lc = static_cast<SkColor4f>(fLightColor);
389 sph->setLightColor({lc.fR, lc.fG, lc.fB});
390
391 sph->setSpecularExp(1/SkTPin(fRoughness, 0.001f, 0.5f));
392 }
393
394 Vec2Value fOffset = {0,0};
395 ScalarValue fRadius = 0,
396 fRotX = 0,
397 fRotY = 0,
398 fRotZ = 0,
399 fRotOrder = 1,
400 fRender = 1;
401
402 VectorValue fLightColor;
403 ScalarValue fLightIntensity = 0,
404 fLightHeight = 0,
405 fLightDirection = 0,
406 fAmbient = 100,
407 fDiffuse = 0,
408 fSpecular = 0,
409 fRoughness = 0.5f;
410
411 using INHERITED = DiscardableAdapterBase<SphereAdapter, SphereNode>;
412 };
413
414 } // namespace
415
attachSphereEffect(const skjson::ArrayValue & jprops,sk_sp<sksg::RenderNode> layer) const416 sk_sp<sksg::RenderNode> EffectBuilder::attachSphereEffect(
417 const skjson::ArrayValue& jprops, sk_sp<sksg::RenderNode> layer) const {
418 auto sphere = sk_make_sp<SphereNode>(std::move(layer), fLayerSize);
419
420 return fBuilder->attachDiscardableAdapter<SphereAdapter>(jprops, fBuilder, std::move(sphere));
421 }
422
423 } // namespace skottie::internal
424