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Commit f9f5822d authored by Andrew Zeng's avatar Andrew Zeng
Browse files

Fix boot animation alpha multiplication computations 

Previously, this was resulting in the output color roughtly as

  output_n = color_n * mask_n^2 * (mask_0 + mask_1 + mask_2 + mask_3)

where n is a color channel between 0 and 3.

This caused extra aliasing around edges, since the alpha fades too
quickly along an edge.

Bug: 239632466
Bug: 258246539
Test: verify pixel values for boot animation match mask on watch + phone
Test: modify uFade value, verify pixel colors match
Change-Id: I86742a181576e684aa698a190a8766f4223de799
parent c3322a82

cmds/bootanimation/BootAnimation.cpp

+15 −15
Original line number Diff line number Diff line
@@ -132,14 +132,14 @@ static const char IMAGE_FRAG_DYNAMIC_COLORING_SHADER_SOURCE[] = R"( 
    uniform sampler2D uTexture;

    uniform float uFade;

    uniform float uColorProgress;

    uniform vec4 uStartColor0;

    uniform vec4 uStartColor1;

    uniform vec4 uStartColor2;

    uniform vec4 uStartColor3;

    uniform vec4 uEndColor0;

    uniform vec4 uEndColor1;

    uniform vec4 uEndColor2;

    uniform vec4 uEndColor3;

    uniform vec3 uStartColor0;

    uniform vec3 uStartColor1;

    uniform vec3 uStartColor2;

    uniform vec3 uStartColor3;

    uniform vec3 uEndColor0;

    uniform vec3 uEndColor1;

    uniform vec3 uEndColor2;

    uniform vec3 uEndColor3;

    varying highp vec2 vUv;

    void main() {

        vec4 mask = texture2D(uTexture, vUv);
@@ -152,12 +152,12 @@ static const char IMAGE_FRAG_DYNAMIC_COLORING_SHADER_SOURCE[] = R"( 
            * step(cWhiteMaskThreshold, g)

            * step(cWhiteMaskThreshold, b)

            * step(cWhiteMaskThreshold, a);

        vec4 color = r * mix(uStartColor0, uEndColor0, uColorProgress)

        vec3 color = r * mix(uStartColor0, uEndColor0, uColorProgress)

                + g * mix(uStartColor1, uEndColor1, uColorProgress)

                + b * mix(uStartColor2, uEndColor2, uColorProgress)

                + a * mix(uStartColor3, uEndColor3, uColorProgress);

        color = mix(color, vec4(vec3((r + g + b + a) * 0.25), 1.0), useWhiteMask);

        gl_FragColor = vec4(color.x, color.y, color.z, (1.0 - uFade)) * color.a;

        color = mix(color, vec3((r + g + b + a) * 0.25), useWhiteMask);

        gl_FragColor = vec4(color.x, color.y, color.z, (1.0 - uFade));

    })";

static const char IMAGE_FRAG_SHADER_SOURCE[] = R"(

    precision mediump float;
@@ -1440,12 +1440,12 @@ void BootAnimation::initDynamicColors() { 
    for (int i = 0; i < DYNAMIC_COLOR_COUNT; i++) {

        float *startColor = mAnimation->startColors[i];

        float *endColor = mAnimation->endColors[i];

        glUniform4f(glGetUniformLocation(mImageShader,

        glUniform3f(glGetUniformLocation(mImageShader,

            (U_START_COLOR_PREFIX + std::to_string(i)).c_str()),

            startColor[0], startColor[1], startColor[2], 1 /* alpha */);

        glUniform4f(glGetUniformLocation(mImageShader,

            startColor[0], startColor[1], startColor[2]);

        glUniform3f(glGetUniformLocation(mImageShader,

            (U_END_COLOR_PREFIX + std::to_string(i)).c_str()),

            endColor[0], endColor[1], endColor[2], 1 /* alpha */);

            endColor[0], endColor[1], endColor[2]);

    }

    mImageColorProgressLocation = glGetUniformLocation(mImageShader, U_COLOR_PROGRESS);

}