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 "SkColor.h"
12 #include "SkPoint.h"
13 #include "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 };
27
28 namespace SkDrawShadowMetrics {
29
30 static constexpr auto kAmbientHeightFactor = 1.0f / 128.0f;
31 static constexpr auto kAmbientGeomFactor = 64.0f;
32
AmbientBlurRadius(SkScalar height)33 inline SkScalar AmbientBlurRadius(SkScalar height) {
34 return height*kAmbientHeightFactor*kAmbientGeomFactor;
35 }
36
AmbientRecipAlpha(SkScalar height)37 inline SkScalar AmbientRecipAlpha(SkScalar height) {
38 return 1.0f + SkTMax(height*kAmbientHeightFactor, 0.0f);
39 }
40
SpotBlurRadius(SkScalar occluderZ,SkScalar lightZ,SkScalar lightRadius)41 inline SkScalar SpotBlurRadius(SkScalar occluderZ, SkScalar lightZ, SkScalar lightRadius) {
42 return lightRadius*SkTPin(occluderZ / (lightZ - occluderZ), 0.0f, 0.95f);
43 }
44
GetSpotParams(SkScalar occluderZ,SkScalar lightX,SkScalar lightY,SkScalar lightZ,SkScalar lightRadius,SkScalar * blurRadius,SkScalar * scale,SkVector * translate)45 inline void GetSpotParams(SkScalar occluderZ, SkScalar lightX, SkScalar lightY, SkScalar lightZ,
46 SkScalar lightRadius,
47 SkScalar* blurRadius, SkScalar* scale, SkVector* translate) {
48 SkScalar zRatio = SkTPin(occluderZ / (lightZ - occluderZ), 0.0f, 0.95f);
49 *blurRadius = lightRadius*zRatio;
50 *scale = SkTMax(lightZ / (lightZ - occluderZ), 1.0f);
51 *translate = SkVector::Make(-zRatio * lightX, -zRatio * lightY);
52 }
53
54 // get bounds prior to the ctm being applied
55 void GetLocalBounds(const SkPath&, const SkDrawShadowRec&, const SkMatrix& ctm, SkRect* bounds);
56
57 }
58
59 #endif
60