1 /*
2 * Copyright 2017 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 #ifndef SkDrawShadowInfo_DEFINED
9 #define SkDrawShadowInfo_DEFINED
10
11 #include "include/core/SkColor.h"
12 #include "include/core/SkPoint.h"
13 #include "include/core/SkPoint3.h"
14
15 class SkMatrix;
16 class SkPath;
17 struct SkRect;
18
19 struct SkDrawShadowRec {
20 SkPoint3 fZPlaneParams;
21 SkPoint3 fLightPos;
22 SkScalar fLightRadius;
23 SkColor fAmbientColor;
24 SkColor fSpotColor;
25 uint32_t fFlags;
26
dumpSkDrawShadowRec27 void dump(std::string &desc, int depth) const
28 {
29 std::string split(depth, '\t');
30 desc += split + "\n SkDrawShadowRec:{ \n";
31 fZPlaneParams.dump(desc, depth + 1);
32 fLightPos.dump(desc, depth + 1);
33 desc += split + "\t fLightRadius: " + std::to_string(fLightRadius) + "\n";
34 desc += split + "\t fAmbientColor: " + std::to_string(fAmbientColor) + "\n";
35 desc += split + "\t fSpotColor: " + std::to_string(fSpotColor) + "\n";
36 desc += split + "\t fFlags: " + std::to_string(fFlags) + "\n";
37 desc += split + "}\n";
38 }
39 };
40
41 namespace SkDrawShadowMetrics {
42
43 static constexpr auto kAmbientHeightFactor = 1.0f / 128.0f;
44 static constexpr auto kAmbientGeomFactor = 64.0f;
45 // Assuming that we have a light height of 600 for the spot shadow,
46 // the spot values will reach their maximum at a height of approximately 292.3077.
47 // We'll round up to 300 to keep it simple.
48 static constexpr auto kMaxAmbientRadius = 300*kAmbientHeightFactor*kAmbientGeomFactor;
49
divide_and_pin(float numer,float denom,float min,float max)50 static inline float divide_and_pin(float numer, float denom, float min, float max) {
51 float result = SkTPin(sk_ieee_float_divide(numer, denom), min, max);
52 // ensure that SkTPin handled non-finites correctly
53 SkASSERT(result >= min && result <= max);
54 return result;
55 }
56
AmbientBlurRadius(SkScalar height)57 inline SkScalar AmbientBlurRadius(SkScalar height) {
58 return SkTMin(height*kAmbientHeightFactor*kAmbientGeomFactor, kMaxAmbientRadius);
59 }
60
AmbientRecipAlpha(SkScalar height)61 inline SkScalar AmbientRecipAlpha(SkScalar height) {
62 return 1.0f + SkTMax(height*kAmbientHeightFactor, 0.0f);
63 }
64
SpotBlurRadius(SkScalar occluderZ,SkScalar lightZ,SkScalar lightRadius)65 inline SkScalar SpotBlurRadius(SkScalar occluderZ, SkScalar lightZ, SkScalar lightRadius) {
66 return lightRadius*divide_and_pin(occluderZ, lightZ - occluderZ, 0.0f, 0.95f);
67 }
68
GetSpotParams(SkScalar occluderZ,SkScalar lightX,SkScalar lightY,SkScalar lightZ,SkScalar lightRadius,SkScalar * blurRadius,SkScalar * scale,SkVector * translate)69 inline void GetSpotParams(SkScalar occluderZ, SkScalar lightX, SkScalar lightY, SkScalar lightZ,
70 SkScalar lightRadius,
71 SkScalar* blurRadius, SkScalar* scale, SkVector* translate) {
72 SkScalar zRatio = divide_and_pin(occluderZ, lightZ - occluderZ, 0.0f, 0.95f);
73 *blurRadius = lightRadius*zRatio;
74 *scale = divide_and_pin(lightZ, lightZ - occluderZ, 1.0f, 1.95f);
75 *translate = SkVector::Make(-zRatio * lightX, -zRatio * lightY);
76 }
77
78 // Create the transformation to apply to a path to get its base shadow outline, given the light
79 // parameters and the path's 3D transformation (given by ctm and zPlaneParams).
80 // Also computes the blur radius to apply the transformed outline.
81 bool GetSpotShadowTransform(const SkPoint3& lightPos, SkScalar lightRadius,
82 const SkMatrix& ctm, const SkPoint3& zPlaneParams,
83 const SkRect& pathBounds, SkMatrix* shadowTransform, SkScalar* radius);
84
85 // get bounds prior to the ctm being applied
86 void GetLocalBounds(const SkPath&, const SkDrawShadowRec&, const SkMatrix& ctm, SkRect* bounds);
87
88 }
89
90 #endif
91