diff options
Diffstat (limited to 'libs/hwui/AmbientShadow.cpp')
| -rw-r--r-- | libs/hwui/AmbientShadow.cpp | 15 |
1 files changed, 9 insertions, 6 deletions
diff --git a/libs/hwui/AmbientShadow.cpp b/libs/hwui/AmbientShadow.cpp index 0a210d6927dc..a4100a2d44fb 100644 --- a/libs/hwui/AmbientShadow.cpp +++ b/libs/hwui/AmbientShadow.cpp @@ -45,8 +45,9 @@ /** * Other constants: */ -// For the edge of the penumbra, the opacity is 0. -#define OUTER_OPACITY (0.0f) +// For the edge of the penumbra, the opacity is 0. After transform (1 - alpha), +// it is 1. +#define TRANSFORMED_OUTER_OPACITY (1.0f) // Once the alpha difference is greater than this threshold, we will allocate extra // edge vertices. @@ -83,11 +84,13 @@ inline float getAlphaFromFactoredZ(float factoredZ) { return 1.0 / (1 + MathUtils::max(factoredZ, 0.0f)); } +// The shader is using gaussian function e^-(1-x)*(1-x)*4, therefore, we transform +// the alpha value to (1 - alpha) inline float getTransformedAlphaFromAlpha(float alpha) { - return acosf(1.0f - 2.0f * alpha); + return 1.0f - alpha; } -// The output is ranged from 0 to M_PI. +// The output is ranged from 0 to 1. inline float getTransformedAlphaFromFactoredZ(float factoredZ) { return getTransformedAlphaFromAlpha(getAlphaFromFactoredZ(factoredZ)); } @@ -249,7 +252,7 @@ void AmbientShadow::createAmbientShadow(bool isCasterOpaque, indexBuffer[indexBufferIndex++] = vertexBufferIndex; indexBuffer[indexBufferIndex++] = currentInnerVertexIndex; AlphaVertex::set(&shadowVertices[vertexBufferIndex++], outerVertex.x, - outerVertex.y, OUTER_OPACITY); + outerVertex.y, TRANSFORMED_OUTER_OPACITY); if (j == 0) { outerStart = outerVertex; @@ -285,7 +288,7 @@ void AmbientShadow::createAmbientShadow(bool isCasterOpaque, (outerLast * startWeight + outerNext * k) / extraVerticesNumber; indexBuffer[indexBufferIndex++] = vertexBufferIndex; AlphaVertex::set(&shadowVertices[vertexBufferIndex++], currentOuter.x, - currentOuter.y, OUTER_OPACITY); + currentOuter.y, TRANSFORMED_OUTER_OPACITY); if (!isCasterOpaque) { umbraVertices[umbraIndex++] = vertexBufferIndex; |