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- /*
- * Copyright 2017 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #ifndef SkDrawShadowInfo_DEFINED
- #define SkDrawShadowInfo_DEFINED
- #include "include/core/SkColor.h"
- #include "include/core/SkPoint.h"
- #include "include/core/SkPoint3.h"
- class SkMatrix;
- class SkPath;
- struct SkRect;
- struct SkDrawShadowRec {
- SkPoint3 fZPlaneParams;
- SkPoint3 fLightPos;
- SkScalar fLightRadius;
- SkColor fAmbientColor;
- SkColor fSpotColor;
- uint32_t fFlags;
- };
- namespace SkDrawShadowMetrics {
- static constexpr auto kAmbientHeightFactor = 1.0f / 128.0f;
- static constexpr auto kAmbientGeomFactor = 64.0f;
- // Assuming that we have a light height of 600 for the spot shadow,
- // the spot values will reach their maximum at a height of approximately 292.3077.
- // We'll round up to 300 to keep it simple.
- static constexpr auto kMaxAmbientRadius = 300*kAmbientHeightFactor*kAmbientGeomFactor;
- static inline float divide_and_pin(float numer, float denom, float min, float max) {
- float result = SkTPin(sk_ieee_float_divide(numer, denom), min, max);
- // ensure that SkTPin handled non-finites correctly
- SkASSERT(result >= min && result <= max);
- return result;
- }
- inline SkScalar AmbientBlurRadius(SkScalar height) {
- return SkTMin(height*kAmbientHeightFactor*kAmbientGeomFactor, kMaxAmbientRadius);
- }
- inline SkScalar AmbientRecipAlpha(SkScalar height) {
- return 1.0f + SkTMax(height*kAmbientHeightFactor, 0.0f);
- }
- inline SkScalar SpotBlurRadius(SkScalar occluderZ, SkScalar lightZ, SkScalar lightRadius) {
- return lightRadius*divide_and_pin(occluderZ, lightZ - occluderZ, 0.0f, 0.95f);
- }
- inline void GetSpotParams(SkScalar occluderZ, SkScalar lightX, SkScalar lightY, SkScalar lightZ,
- SkScalar lightRadius,
- SkScalar* blurRadius, SkScalar* scale, SkVector* translate) {
- SkScalar zRatio = divide_and_pin(occluderZ, lightZ - occluderZ, 0.0f, 0.95f);
- *blurRadius = lightRadius*zRatio;
- *scale = divide_and_pin(lightZ, lightZ - occluderZ, 1.0f, 1.95f);
- *translate = SkVector::Make(-zRatio * lightX, -zRatio * lightY);
- }
- // Create the transformation to apply to a path to get its base shadow outline, given the light
- // parameters and the path's 3D transformation (given by ctm and zPlaneParams).
- // Also computes the blur radius to apply the transformed outline.
- bool GetSpotShadowTransform(const SkPoint3& lightPos, SkScalar lightRadius,
- const SkMatrix& ctm, const SkPoint3& zPlaneParams,
- const SkRect& pathBounds, SkMatrix* shadowTransform, SkScalar* radius);
- // get bounds prior to the ctm being applied
- void GetLocalBounds(const SkPath&, const SkDrawShadowRec&, const SkMatrix& ctm, SkRect* bounds);
- }
- #endif
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