Brian Osman | 7c979f5 | 2019-02-12 13:27:51 -0500 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2019 Google LLC |
| 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 "SkParticleAffector.h" |
| 9 | |
| 10 | #include "SkParticleData.h" |
| 11 | #include "SkRandom.h" |
| 12 | |
| 13 | class SkDirectionalForceAffector : public SkParticleAffector { |
| 14 | public: |
| 15 | SkDirectionalForceAffector(SkVector force = { 0.0f, 0.0f }) : fForce(force) {} |
| 16 | |
| 17 | REFLECTED(SkDirectionalForceAffector, SkParticleAffector) |
| 18 | |
| 19 | void apply(SkParticleUpdateParams& params, SkParticlePoseAndVelocity& pv) override { |
| 20 | pv.fVelocity.fLinear += fForce * params.fDeltaTime; |
| 21 | } |
| 22 | |
| 23 | void visitFields(SkFieldVisitor* v) override { |
| 24 | v->visit("Force", fForce); |
| 25 | } |
| 26 | |
| 27 | private: |
| 28 | SkVector fForce; |
| 29 | }; |
| 30 | |
| 31 | class SkRangedForceAffector : public SkParticleAffector { |
| 32 | public: |
| 33 | SkRangedForceAffector(const SkCurve& angle = 0.0f, |
| 34 | const SkCurve& strength = 0.0f, |
| 35 | bool bidirectional = false) |
| 36 | : fAngle(angle) |
| 37 | , fStrength(strength) |
| 38 | , fBidirectional(bidirectional) {} |
| 39 | |
| 40 | REFLECTED(SkRangedForceAffector, SkParticleAffector) |
| 41 | |
| 42 | void apply(SkParticleUpdateParams& params, SkParticlePoseAndVelocity& pv) override { |
| 43 | float angle = fAngle.eval(params.fParticleT, *params.fStableRandom); |
| 44 | SkScalar c, s = SkScalarSinCos(angle, &c); |
| 45 | float strength = fStrength.eval(params.fParticleT, *params.fStableRandom); |
| 46 | if (fBidirectional && params.fStableRandom->nextBool()) { |
| 47 | strength = -strength; |
| 48 | } |
| 49 | SkVector force = { c * strength, s * strength }; |
| 50 | pv.fVelocity.fLinear += force * params.fDeltaTime; |
| 51 | } |
| 52 | |
| 53 | void visitFields(SkFieldVisitor* v) override { |
| 54 | v->visit("Angle", fAngle); |
| 55 | v->visit("Strength", fStrength); |
| 56 | v->visit("Bidirectional", fBidirectional); |
| 57 | } |
| 58 | |
| 59 | private: |
| 60 | SkCurve fAngle; |
| 61 | SkCurve fStrength; |
| 62 | bool fBidirectional; |
| 63 | }; |
| 64 | |
| 65 | class SkPointForceAffector : public SkParticleAffector { |
| 66 | public: |
| 67 | SkPointForceAffector(SkPoint point = { 0.0f, 0.0f }, SkScalar constant = 0.0f, |
| 68 | SkScalar invSquare = 0.0f) |
| 69 | : fPoint(point), fConstant(constant), fInvSquare(invSquare) {} |
| 70 | |
| 71 | REFLECTED(SkPointForceAffector, SkParticleAffector) |
| 72 | |
| 73 | void apply(SkParticleUpdateParams& params, SkParticlePoseAndVelocity& pv) override { |
| 74 | SkVector toPoint = fPoint - pv.fPose.fPosition; |
| 75 | SkScalar lenSquare = toPoint.dot(toPoint); |
| 76 | toPoint.normalize(); |
| 77 | pv.fVelocity.fLinear += toPoint * (fConstant + (fInvSquare/lenSquare)) * params.fDeltaTime; |
| 78 | } |
| 79 | |
| 80 | void visitFields(SkFieldVisitor* v) override { |
| 81 | v->visit("Point", fPoint); |
| 82 | v->visit("Constant", fConstant); |
| 83 | v->visit("InvSquare", fInvSquare); |
| 84 | } |
| 85 | |
| 86 | private: |
| 87 | SkPoint fPoint; |
| 88 | SkScalar fConstant; |
| 89 | SkScalar fInvSquare; |
| 90 | }; |
| 91 | |
| 92 | class SkOrientAlongVelocityAffector : public SkParticleAffector { |
| 93 | public: |
| 94 | SkOrientAlongVelocityAffector() {} |
| 95 | |
| 96 | REFLECTED(SkOrientAlongVelocityAffector, SkParticleAffector) |
| 97 | |
| 98 | void apply(SkParticleUpdateParams& params, SkParticlePoseAndVelocity& pv) override { |
| 99 | SkVector heading = pv.fVelocity.fLinear; |
| 100 | if (!heading.normalize()) { |
| 101 | heading.set(0, -1); |
| 102 | } |
| 103 | pv.fPose.fHeading = heading; |
| 104 | } |
| 105 | |
| 106 | void visitFields(SkFieldVisitor*) override {} |
| 107 | }; |
| 108 | |
| 109 | class SkJitterAffector : public SkParticleAffector { |
| 110 | public: |
| 111 | SkJitterAffector() {} |
| 112 | |
| 113 | REFLECTED(SkJitterAffector, SkParticleAffector) |
| 114 | |
| 115 | void apply(SkParticleUpdateParams& params, SkParticlePoseAndVelocity& pv) override { |
| 116 | pv.fVelocity.fLinear.fX += fX.eval(*params.fRandom); |
| 117 | } |
| 118 | |
| 119 | void visitFields(SkFieldVisitor* v) override { |
| 120 | v->visit("X", fX); |
| 121 | } |
| 122 | |
| 123 | private: |
| 124 | SkRangedFloat fX; |
| 125 | }; |
| 126 | |
| 127 | void SkParticleAffector::RegisterAffectorTypes() { |
| 128 | REGISTER_REFLECTED(SkParticleAffector); |
| 129 | REGISTER_REFLECTED(SkDirectionalForceAffector); |
| 130 | REGISTER_REFLECTED(SkRangedForceAffector); |
| 131 | REGISTER_REFLECTED(SkPointForceAffector); |
| 132 | REGISTER_REFLECTED(SkOrientAlongVelocityAffector); |
| 133 | REGISTER_REFLECTED(SkJitterAffector); |
| 134 | } |
| 135 | |
| 136 | sk_sp<SkParticleAffector> SkParticleAffector::MakeDirectionalForce(SkVector force) { |
| 137 | return sk_sp<SkParticleAffector>(new SkDirectionalForceAffector(force)); |
| 138 | } |
| 139 | |
| 140 | sk_sp<SkParticleAffector> SkParticleAffector::MakeRangedForce(const SkCurve& angle, |
| 141 | const SkCurve& strength, |
| 142 | bool bidirectional) { |
| 143 | return sk_sp<SkParticleAffector>(new SkRangedForceAffector(angle, strength, bidirectional)); |
| 144 | } |
| 145 | |
| 146 | sk_sp<SkParticleAffector> MakePointForce(SkPoint point, SkScalar constant, SkScalar invSquare) { |
| 147 | return sk_sp<SkParticleAffector>(new SkPointForceAffector(point, constant, invSquare)); |
| 148 | } |
| 149 | |
| 150 | sk_sp<SkParticleAffector> MakeOrientAlongVelocity() { |
| 151 | return sk_sp<SkParticleAffector>(new SkOrientAlongVelocityAffector()); |
| 152 | } |