Merge changes I8bea0b0a,Id7ebe430,I0194d91e,I782e86c6 into main

    return GlassRain(

        dropPos, cellMainDropMask, trailDropsPos, cellDroppletsMask, cellTrailMask, cellUv);

}

/**

 * Generate rain drops that stay in place on the glass surface.

 */

vec3 generateStaticGlassRain(vec2 uv, half screenAspectRatio, half time, half intensity) {

    vec2 gridSize = vec2(15., 15.);

    // Aspect ratio impacts visible cells.

    gridSize.y /= screenAspectRatio;

    // scale the UV to allocate number of rows and columns.

    vec2 gridUv = uv * gridSize;

    // Invert y (otherwise it goes from 0=top to 1=bottom).

    gridUv.y = 1. - gridUv.y;

    // Generate column id, to offset columns vertically (so rain is not aligned).

    float columnId = idGenerator(floor(gridUv.x));

    gridUv.y += columnId * 5.6;

    // Get the cell ID based on the grid position. Value from 0 to 1.

    float cellId = idGenerator(floor(gridUv));

    // Draw rain drops with a probability based on the cell id.

    if (cellId < 0.8) {

        return vec3(0.);

    }

    // For each cell, we set the internal UV from -0.5 (left, bottom) to 0.5 (right, top).

    vec2 cellUv = fract(gridUv) - 0.5;

    vec2 pixUv = cellUv;

    pixUv.x *= -1;

    vec2 pixDistance = screenSize * pixUv / gridSize;

    float delay = 3.5173;

    float duration = 8.2;

    float t = time + 100. * cellId;

    float circletime = floor(t / (duration + delay));

    float delayOffset = idGenerator(floor(gridUv) + vec2(circletime, 43.14 * cellId));

    float normalizedTime = map(/* value */     mod(t, duration + delay) - delay * delayOffset,

                               /* in range */  0, duration,

                               /* out range */ 0, 1);

    // Apply a curve to the time.

    normalizedTime *= normalizedTime;

    vec2 pos = cellUv * (1.5 - 0.5 * cellId + normalizedTime * 50.);

    float mask = smoothstep(0.3, 0.2, length(pos))

                 * smoothstep(0.2, 0.06, normalizedTime)

                 * smoothstep(0., 0.45, intensity);

    return vec3(pos * 0.19, mask);

}

/*

 * Copyright (C) 2024 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

uniform shader texture;

uniform half thickness;

/**

 * Returns whether the current fragcoord lies on the outline, return range [0, 1].

 * 0 = no outline, 1 = outline

 * This assumes that the given texture has a transparent background and evaluates whether it's an

 * outline with finite differencing.

 */

vec4 main(float2 fragCoord) {

    float aN = texture.eval(fragCoord + vec2(0., thickness)).a;

    float aS = texture.eval(fragCoord + vec2(0., -thickness)).a;

    float dY = (aN - aS) * 0.5;

    dY = max(dY, 0.0);

    half outline = smoothstep(0.1, 1.8, dY * 5.0);

    // Return the results in the R channel.

    return vec4(outline, 0., 0., 0.);

}

#include "shaders/rain_constants.agsl"

vec4 main(float2 fragCoord) {

    // 0. Add a bit of noise so that the droplets are not perfect circles.

    fragCoord += vec2(valueNoise(fragCoord) * 0.015 - 0.0025);

    float2 uv = fragCoord / screenSize;

    // 1. Generate small glass rain.

    droppletsUvMasked = mix(droppletsUvMasked,

        medDrippingRain.dropplets * medDrippingRain.droppletsMask, medDrippingRain.droppletsMask);

    // 4. Distort uv for the rain drops and dropplets.

    // 4. Add static rain droplets on the glass surface. (They stay in place and dissapate.)

    vec3 staticRain = generateStaticGlassRain(uv, screenAspectRatio, time, intensity);

    dropMask = max(dropMask, staticRain.z);

    dropUvMasked = mix(dropUvMasked, staticRain.xy * staticRain.z, staticRain.z);

    // 5. Distort uv for the rain drops and dropplets.

    float distortionDrop = -0.1;

    vec2 uvDiffractionOffsets =

        distortionDrop * dropUvMasked;

    vec3 sampledColor = texture.eval(fragCoord + uvDiffractionOffsets * s).rgb;

    color.rgb = mix(color.rgb, sampledColor, max(dropMask, droppletsMask));

    // 5. Add color tint to the rain drops.

    // 6. Add color tint to the rain drops.

    color.rgb = mix(

        color.rgb,

        dropTint,

        dropTintIntensity * smoothstep(0.7, 1., max(dropMask, droppletsMask)));

    // 6. Add highlight to the drops.

    // 7. Add highlight to the drops.

    color.rgb = mix(

        color.rgb,

        highlightColor,

        highlightIntensity

            * smoothstep(0.05, 0.08, max(dropUvMasked * 1.7, droppletsUvMasked * 2.6)).x);

    // 7. Add shadows to the drops.

    // 8. Add shadows to the drops.

    color.rgb = mix(

        color.rgb,

        contactShadowColor,

uniform shader foreground;

uniform shader background;

uniform shader outlineBuffer;

uniform float2 uvOffsetFgd;

uniform float2 uvScaleFgd;

uniform float2 uvOffsetBgd;

#include "shaders/utils.agsl"

#include "shaders/rain_shower.agsl"

#include "shaders/rain_constants.agsl"

#include "shaders/rain_splash.agsl"

// Controls how visible the rain drops are.

const float rainVisibility = 0.4;

/**

 * Draws splashes around the outline of the given image.

 */

vec3 drawSplashes(vec2 uv, vec2 fragCoord, vec3 color) {

    /** 1. Make a grid */

    vec2 gridSize = vec2(15., 15.);

    // Aspect ratio impacts visible cells.

    gridSize.y /= screenAspectRatio;

    // Scale the UV to allocate number of rows and columns.

    vec2 gridUv = uv * gridSize;

    // Invert y (otherwise it goes from 0=top to 1=bottom).

    gridUv.y = 1. - gridUv.y;

    // Generate column id, to offset columns vertically (so rain is not aligned).

    float columnOffset = idGenerator(floor(gridUv.x));

    gridUv.y += columnOffset * 2.6;

    // For each cell, we set the internal UV from -0.5 (left, bottom) to 0.5 (right, top).

    vec2 cellUv = fract(gridUv) - 0.5;

    vec2 pixUv = cellUv;

    pixUv.x *= -1;

    vec2 pixDistance = screenSize * pixUv / gridSize;

    float2 uvTextureFgd = (fragCoord + pixDistance) * uvScaleFgd + uvOffsetFgd;

    float outline = step(0.1, outlineBuffer.eval(uvTextureFgd).r);

    if (outline < 0.1) {

        // Simply return the given color when it's not considered as an outline.

        return color;

    }

    float t = time + 53.512 * columnOffset;

    float delay = 1.5173;

    float duration = 1.2;

    float circletime = floor(t / (duration + delay));

    // Get the cell ID based on the grid position. [0, 1].

    float cellId = idGenerator(floor(gridUv) + vec2(circletime, 23.14));

    // Normalized time [0, 1].

    float cellTime = max((mod(t + delay * cellId, duration + delay) - delay) / duration, 0.);

    float splash = drawSplash(cellUv, cellTime) * smoothstep(0., 0.45, intensity);

    return normalBlendWithWhiteSrc(color, splash);

}

vec4 main(float2 fragCoord) {

    float2 uv = fragCoord / screenSize;

    // 4. Blend with the foreground. Any effect from here will be in front of the subject.

    color.rgb = normalBlend(color.rgb, colorForeground.rgb, colorForeground.a);

    // 5. Generate a layer of rain in front of the subject (bigger and faster).

    // 5. Draw splashes

    color.rgb = drawSplashes(uv, fragCoord, color.rgb);

    // 6. Generate a layer of rain in front of the subject (bigger and faster).

    rain = generateRain(

          uv,

          screenAspectRatio,

/*

 * Copyright (C) 2024 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

/**

 * Draw a single splash.

 * @param cellUv Range of [-0.5, 0.5]: left bottom (-0.5, -0.5), right top (0.5, 0.5).

 * @param cellTime Normalized cellTime range of [0, 1].

 */

float drawSplash(vec2 cellUv, float cellTime) {

    /** 0. Adjust UV and time. */

    cellUv = cellUv * 0.5;

    cellUv += 0.1;

    float t = 0.408 + cellTime * 4.;

    /** 1. Start of drawing a splash */

    // Draw one side of a splash (a crescent) using two circles, by overlapping them with a slight

    // offset. Then we reflect the splash to get the full splash.

    // Reflect the splash.

    vec2 uvAbs = abs(cellUv);

    // Center of the splash (of the right splash)

    vec2 center = vec2(0.22, -0.01);

    float splashMaskCircle1 = sdfCircle(uvAbs - center, 0.164);

    float splashMaskCircle2 = sdfCircle(uvAbs - vec2(0.04, 0.) - center, 0.164);

    splashMaskCircle1 = smoothstep(0.052, 0.12, splashMaskCircle1);

    splashMaskCircle2 = smoothstep(0.1, 0.152, splashMaskCircle2);

    // Here, we have a full splash that covers the entire cell

    float splash = splashMaskCircle1 - splashMaskCircle2;

    // Mask the splash so that it doesn't cover the entire cell.

    float circleMask = sdfCircle(cellUv - vec2(0., 0.15), -0.004);

    float splashColor = splash * smoothstep(0.152, 0.1, circleMask);

    // Another mask for the splash to reveal it vertically.

    float maskThickHalf = 0.052;

    float maskFade = 0.05;

    vec2 maskMiddle = vec2(-0.1, -0.5);

    maskMiddle.y *= sin(mod(t, 4.4));

    float mask =

       smoothstep(maskMiddle.y - maskThickHalf - maskFade,

                  maskMiddle.y - maskThickHalf,

                  cellUv.y) -

       smoothstep(maskMiddle.y + maskThickHalf,

                  maskMiddle.y + maskThickHalf + maskFade,

                  cellUv.y);

    splashColor *= mask;

    /** End of drawing a splash */

    /** 2. Start of drawing a vertical line of the splash */

    // Draw the vertical line.

    float verticalLine = 0.035;

    float lineCenter = 0.192;

    float lineColor = 0.4 *

       (smoothstep(-verticalLine, 0., cellUv.x) - smoothstep(0., verticalLine, cellUv.x)) *

        smoothstep(0.008, -0.156, sdfCircle(cellUv - vec2(0., lineCenter), 0.164));

    // Mask the vertical line to reveal it vertically.

    float lineMaskThickHalf = 0.124;

    float lineMaskFade = 0.170;

    vec2 lineMaskMiddle = vec2(-0.01, 2.71);

    lineMaskMiddle.y *= sin(mod(t, 4.4) - 0.168);

    float lineMask =

       smoothstep(lineMaskMiddle.y - lineMaskThickHalf - lineMaskFade,

                  lineMaskMiddle.y - lineMaskThickHalf,

                  cellUv.y) -

       smoothstep(lineMaskMiddle.y + lineMaskThickHalf,

                  lineMaskMiddle.y + lineMaskThickHalf + lineMaskFade,

                  cellUv.y);

    float line = lineColor * lineMask;

    /** End of drawing the vertical line of the splash */

    /** 3. Composite the splash and the line. */

    return splashColor * (1. - line) + line;

}