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Commit 12d9526d authored by Chris Craik's avatar Chris Craik
Browse files

Simplify umbra calculation 

Reuse pre-computed values

Change-Id: Ia7725be0ec3ac58af477fcb8de375f5faa05abf4
parent f3560a13

libs/hwui/SpotShadow.cpp

+8 −18
Original line number Diff line number Diff line
@@ -743,9 +743,10 @@ void SpotShadow::generateTriangleStrip(const Vector2* penumbra, int penumbraLeng 
    int stripSize = getStripSize(rays, layers);

    AlphaVertex* shadowVertices = shadowTriangleStrip.alloc<AlphaVertex>(stripSize);

    int currentIndex = 0;

    int firstInLayer = 0;

    // Calculate the vertex values in the penumbra area.

    for (int r = 0; r < layers; r++) {

        int firstInEachLayer = currentIndex;

        firstInLayer = currentIndex;

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

            float dx = sinf(step * i);

            float dy = cosf(step * i);
@@ -755,19 +756,17 @@ void SpotShadow::generateTriangleStrip(const Vector2* penumbra, int penumbraLeng 
                float deltaDist = layerRatio * (umbraDistPerRay[i] - penumbraDistPerRay[i]);

                float currentDist = penumbraDistPerRay[i] + deltaDist;

                float op = calculateOpacity(layerRatio, deltaDist);

                AlphaVertex::set(&shadowVertices[currentIndex],

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

                        dx * currentDist + centroid.x,

                        dy * currentDist + centroid.y,

                        layerRatio * op * strength);

                currentIndex++;

            }

        }



        // Duplicate the vertices from one layer to another one to make triangle

        // strip.

        shadowVertices[currentIndex++] = shadowVertices[firstInEachLayer];

        firstInEachLayer++;

        shadowVertices[currentIndex++] = shadowVertices[firstInEachLayer];

        shadowVertices[currentIndex++] = shadowVertices[firstInLayer + 0];

        shadowVertices[currentIndex++] = shadowVertices[firstInLayer + 1];

    }



    int lastInPenumbra = currentIndex - 1;
@@ -779,23 +778,14 @@ void SpotShadow::generateTriangleStrip(const Vector2* penumbra, int penumbraLeng 
    int firstInUmbra = currentIndex;



    // traverse the umbra area in a zig zag pattern for strips.

    const int innerRingStartIndex = firstInLayer + 1;

    for (int k = 0; k < rays; k++) {

        int i = k / 2;

        if ((k & 1) == 1) {

            i = rays - i - 1;

        }

        float dx = sinf(step * i);

        float dy = cosf(step * i);



        float ratio = 1.0;

        float deltaDist = ratio * (umbraDistPerRay[i] - penumbraDistPerRay[i]);

        float currentDist = penumbraDistPerRay[i] + deltaDist;

        float op = calculateOpacity(ratio, deltaDist);

        AlphaVertex::set(&shadowVertices[currentIndex],

                dx * currentDist + centroid.x, dy * currentDist + centroid.y,

                ratio * op * strength);

        currentIndex++;



        // copy already computed values for umbra vertices

        shadowVertices[currentIndex++] = shadowVertices[innerRingStartIndex + i * 2];

    }



    // Back fill the one vertex for jumping from penumbra to umbra.