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Commit ecf091e1 authored by ztenghui's avatar ztenghui
Browse files

Update the shadow fall off function from cosine to gaussian. 

Also tune the parameters to match a better look designed by UX team.
For ambient part, the acos transformed alpha is not needed any more.

b/19370798

Change-Id: I20d2615d1be502eb900942ed756aecd1660dee48
parent b929d658

core/res/res/values/dimens.xml

+4 −4
Original line number Diff line number Diff line
@@ -380,10 +380,10 @@ 


    <!-- Lighting and shadow properties -->

    <dimen name="light_y">-200dp</dimen>

    <dimen name="light_z">800dp</dimen>

    <dimen name="light_radius">600dp</dimen>

    <item type="dimen" format="float" name="ambient_shadow_alpha">0.075</item>

    <item type="dimen" format="float" name="spot_shadow_alpha">0.15</item>

    <dimen name="light_z">600dp</dimen>

    <dimen name="light_radius">800dp</dimen>

    <item type="dimen" format="float" name="ambient_shadow_alpha">0.039</item>

    <item type="dimen" format="float" name="spot_shadow_alpha">0.19</item>



     <!-- Floating toolbar dimensions -->

     <dimen name="floating_toolbar_height">48dp</dimen>

libs/hwui/AmbientShadow.cpp

+9 −6
Original line number Diff line number Diff line
@@ -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;

libs/hwui/ProgramCache.cpp

+3 −2
Original line number Diff line number Diff line
@@ -240,8 +240,9 @@ const char* gFS_Main_ModulateColor = 
const char* gFS_Main_ApplyVertexAlphaLinearInterp =

        "    fragColor *= alpha;\n";

const char* gFS_Main_ApplyVertexAlphaShadowInterp =

        "    fragColor *= (1.0 - cos(alpha)) / 2.0;\n";



        // Use a gaussian function for the shadow fall off. Note that alpha here

        // is actually (1.0 - alpha) for saving computation.

        "    fragColor *= exp(- alpha * alpha * 4.0) - 0.018;\n";

const char* gFS_Main_FetchTexture[2] = {

        // Don't modulate

        "    fragColor = texture2D(baseSampler, outTexCoords);\n",

libs/hwui/SpotShadow.cpp

+7 −4
Original line number Diff line number Diff line
@@ -44,6 +44,9 @@ 
// For each RADIANS_DIVISOR, we would allocate one more vertex b/t the normals.

#define SPOT_CORNER_RADIANS_DIVISOR (M_PI / SPOT_EXTRA_CORNER_VERTEX_PER_PI)



// For performance, we use (1 - alpha) value for the shader input.

#define TRANSFORMED_PENUMBRA_ALPHA 1.0f

#define TRANSFORMED_UMBRA_ALPHA 0.0f



#include <math.h>

#include <stdlib.h>
@@ -964,11 +967,11 @@ void SpotShadow::generateTriangleStrip(bool isCasterOpaque, float shadowStrength 
    // Fill the IB and VB for the penumbra area.

    for (int i = 0; i < newPenumbraLength; i++) {

        AlphaVertex::set(&shadowVertices[vertexBufferIndex++], newPenumbra[i].x,

                newPenumbra[i].y, 0.0f);

                newPenumbra[i].y, TRANSFORMED_PENUMBRA_ALPHA);

    }

    for (int i = 0; i < umbraLength; i++) {

        AlphaVertex::set(&shadowVertices[vertexBufferIndex++], umbra[i].x, umbra[i].y,

                M_PI);

                TRANSFORMED_UMBRA_ALPHA);

    }



    for (int i = 0; i < verticesPairIndex; i++) {
@@ -1008,14 +1011,14 @@ void SpotShadow::generateTriangleStrip(bool isCasterOpaque, float shadowStrength 
            indexBuffer[indexBufferIndex++] = newPenumbraLength + i;

            indexBuffer[indexBufferIndex++] = vertexBufferIndex;

            AlphaVertex::set(&shadowVertices[vertexBufferIndex++],

                    closerVertex.x, closerVertex.y, M_PI);

                    closerVertex.x, closerVertex.y, TRANSFORMED_UMBRA_ALPHA);

        }

    } else {

        // If there is no occluded umbra at all, then draw the triangle fan

        // starting from the centroid to all umbra vertices.

        int lastCentroidIndex = vertexBufferIndex;

        AlphaVertex::set(&shadowVertices[vertexBufferIndex++], centroid.x,

                centroid.y, M_PI);

                centroid.y, TRANSFORMED_UMBRA_ALPHA);

        for (int i = 0; i < umbraLength; i++) {

            indexBuffer[indexBufferIndex++] = newPenumbraLength + i;

            indexBuffer[indexBufferIndex++] = lastCentroidIndex;