如何使用最新的Mapbox-gl-js版本避免透明度重叠？

Question

[我一直在（https://bl.ocks.org/andrewharvey/9490afae78301c047adddfb06523f6f1）处处理建筑几何体示例中的阴影，并能够与透明版本的mapbox-gl-js混合使用透明层，使其成为一个统一的alpha值。

但是，当我将mapbox-gl-js版本更改为v0.54.0或更高版本时，它不再将阴影混合为统一值。我已经对gl.blendFunc（）和gl.blendFuncSeparate（）进行了实验，但似乎仍然混合了奇怪的抗锯齿问题或重叠的混浊。

如何避免出现此透明性问题并获得与提供的第一个示例相似的结果。

0.53.1：1.6.1：

使用版本0.53.1的代码：

<!DOCTYPE html>
<html>
<head>
    <title>Mapbox GL JS debug page</title>
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <link href='https://api.tiles.mapbox.com/mapbox-gl-js/v0.53.1/mapbox-gl.css' rel='stylesheet' />
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 100%; }
        #time { position: absolute; width: 90%; top: 10px; left: 10px; }
    </style>
</head>

<body>
<div id='map'></div>
<input id='time' type='range' min="0" max="86400" />

<script src='https://api.tiles.mapbox.com/mapbox-gl-js/v0.53.1/mapbox-gl.js'></script>
<script src='https://unpkg.com/[email protected]/suncalc.js'></script>
<!-- <script src='/debug/access_token_generated.js'></script> -->
<script>
mapboxgl.accessToken = 'pk.eyJ1IjoiYWxhbnRnZW8tcHJlc2FsZXMiLCJhIjoiY2pzcTA4NjRiMTMxczQzcDFqa29maXk3bSJ9.pVYNTFKfcOXA_U_5TUwDWw';
var map = window.map = new mapboxgl.Map({
    container: 'map',
    zoom: 15,
    center: [-74.0059, 40.7064],
    style: 'mapbox://styles/mapbox/streets-v11',
    hash: true
});
var date = new Date();
var time = date.getHours() * 60 * 60 + date.getMinutes() * 60 + date.getSeconds();
var timeInput = document.getElementById('time');
timeInput.value = time;
timeInput.oninput = () => {
    time = +timeInput.value;
    date.setHours(Math.floor(time / 60 / 60));
    date.setMinutes(Math.floor(time / 60) % 60);
    date.setSeconds(time % 60);
    map.triggerRepaint();
};
map.addControl(new mapboxgl.NavigationControl());
class BuildingShadows {
    constructor() {
        this.id = 'building-shadows';
        this.type = 'custom';
        this.renderingMode = '3d';
        this.opacity = 0.5;
    }
    onAdd(map, gl) {
        this.map = map;
        const vertexSource = `
        uniform mat4 u_matrix;
        uniform float u_height_factor;
        uniform float u_altitude;
        uniform float u_azimuth;
        attribute vec2 a_pos;
        attribute vec4 a_normal_ed;
        attribute lowp vec2 a_base;
        attribute lowp vec2 a_height;
        void main() {
            float base = max(0.0, a_base.x);
            float height = max(0.0, a_height.x);
            float t = mod(a_normal_ed.x, 2.0);
            vec4 pos = vec4(a_pos, t > 0.0 ? height : base, 1);
            float len = pos.z * u_height_factor / tan(u_altitude);
            pos.x += cos(u_azimuth) * len;
            pos.y += sin(u_azimuth) * len;
            pos.z = 0.0;
            gl_Position = u_matrix * pos;
        }
        `;
        const fragmentSource = `
        void main() {
            gl_FragColor = vec4(0.0, 0.0, 0.0, 0.5);
        }
        `;


        const vertexShader = gl.createShader(gl.VERTEX_SHADER);
        gl.shaderSource(vertexShader, vertexSource);
        gl.compileShader(vertexShader);
        const fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
        console.log(gl.FRAGMENT_SHADER)
        console.log(fragmentShader)
        console.log(fragmentSource)
        gl.shaderSource(fragmentShader, fragmentSource);
        gl.compileShader(fragmentShader);
        this.program = gl.createProgram();
        gl.attachShader(this.program, vertexShader);
        gl.attachShader(this.program, fragmentShader);
        gl.linkProgram(this.program);
        gl.validateProgram(this.program);
        this.uMatrix = gl.getUniformLocation(this.program, "u_matrix");
        this.uHeightFactor = gl.getUniformLocation(this.program, "u_height_factor");
        this.uAltitude = gl.getUniformLocation(this.program, "u_altitude");
        this.uAzimuth = gl.getUniformLocation(this.program, "u_azimuth");
        this.aPos = gl.getAttribLocation(this.program, "a_pos");
        this.aNormal = gl.getAttribLocation(this.program, "a_normal_ed");
        this.aBase = gl.getAttribLocation(this.program, "a_base");
        this.aHeight = gl.getAttribLocation(this.program, "a_height");
    }
    render(gl, matrix) {
        gl.useProgram(this.program);
        const source = this.map.style.sourceCaches['composite'];
        const coords = source.getVisibleCoordinates().reverse();
        const buildingsLayer = map.getLayer('3d-buildings');
        const context = this.map.painter.context;
        const {lng, lat} = this.map.getCenter();
        const pos = SunCalc.getPosition(date, lat, lng);
        gl.uniform1f(this.uAltitude, pos.altitude);
        gl.uniform1f(this.uAzimuth, pos.azimuth + 3 * Math.PI / 2);
        map.setLight({
            anchor: 'map',
            position: [1.5, 180 + pos.azimuth * 180 / Math.PI, 90 - pos.altitude * 180 / Math.PI],
            'position-transition': {duration: 0},
            color: '#fdb'
            // color: `hsl(20, ${50 * Math.cos(pos.altitude)}%, ${ 200 * Math.sin(pos.altitude) }%)`
        }, {duration: 0});
        this.opacity = Math.sin(Math.max(pos.altitude, 0)) * 0.9;

        // ADDED: normalises the colour of the shadows
        gl.blendFunc(gl.SRC_COLOR, gl.CONSTANT_COLOR)
        gl.enable(gl.BLEND)

        for (const coord of coords) {
            const tile = source.getTile(coord);
            const bucket = tile.getBucket(buildingsLayer);
            if (!bucket) continue;
            const [heightBuffer, baseBuffer] = bucket.programConfigurations.programConfigurations['3d-buildings']._buffers;
            gl.uniformMatrix4fv(this.uMatrix, false, coord.posMatrix);
            gl.uniform1f(this.uHeightFactor, Math.pow(2, coord.overscaledZ) / tile.tileSize / 8);
            for (const segment of bucket.segments.get()) {
                const numPrevAttrib = context.currentNumAttributes || 0;
                const numNextAttrib = 2;
                for (let i = numNextAttrib; i < numPrevAttrib; i++) gl.disableVertexAttribArray(i);
                const vertexOffset = segment.vertexOffset || 0;
                gl.enableVertexAttribArray(this.aPos);
                gl.enableVertexAttribArray(this.aNormal);
                gl.enableVertexAttribArray(this.aHeight);
                gl.enableVertexAttribArray(this.aBase);
                bucket.layoutVertexBuffer.bind();
                gl.vertexAttribPointer(this.aPos, 2, gl.SHORT, false, 12, 12 * vertexOffset);
                gl.vertexAttribPointer(this.aNormal, 4, gl.SHORT, false, 12, 4 + 12 * vertexOffset);
                heightBuffer.bind();
                gl.vertexAttribPointer(this.aHeight, 1, gl.FLOAT, false, 4, 4 * vertexOffset);
                baseBuffer.bind();
                gl.vertexAttribPointer(this.aBase, 1, gl.FLOAT, false, 4, 4 * vertexOffset);
                bucket.indexBuffer.bind();
                context.currentNumAttributes = numNextAttrib;
                gl.drawElements(gl.TRIANGLES, segment.primitiveLength * 3, gl.UNSIGNED_SHORT, segment.primitiveOffset * 3 * 2);
            }
        }
    }
}
map.on('load', () => {
    map.removeLayer('building');
    map.addLayer({
        'id': '3d-buildings',
        'source': 'composite',
        'source-layer': 'building',
        'type': 'fill-extrusion',
        'minzoom': 14,
        'paint': {
            'fill-extrusion-color': '#ddd',
            'fill-extrusion-height': ["number", ["get", "height"], 5],
            'fill-extrusion-base': ["number", ["get", "min_height"], 0],
            'fill-extrusion-opacity': 1
        }
    }, 'road-label');
    map.addLayer(new BuildingShadows(), '3d-buildings');
});
</script>
</body>
</html>

使用1.6.1版的代码：

<!DOCTYPE html>
<html>
<head>
    <title>Mapbox GL JS debug page</title>
    <meta charset='utf-8'>
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=no">
    <link href='https://api.tiles.mapbox.com/mapbox-gl-js/v1.6.1/mapbox-gl.css' rel='stylesheet' />
    <style>
        body { margin: 0; padding: 0; }
        html, body, #map { height: 100%; }
        #time { position: absolute; width: 90%; top: 10px; left: 10px; }
    </style>
</head>

<body>
<div id='map'></div>
<input id='time' type='range' min="0" max="86400" />

<script src='https://api.tiles.mapbox.com/mapbox-gl-js/v1.6.1/mapbox-gl.js'></script>
<script src='https://unpkg.com/[email protected]/suncalc.js'></script>
<!-- <script src='/debug/access_token_generated.js'></script> -->
<script>
mapboxgl.accessToken = 'pk.eyJ1IjoiYWxhbnRnZW8tcHJlc2FsZXMiLCJhIjoiY2pzcTA4NjRiMTMxczQzcDFqa29maXk3bSJ9.pVYNTFKfcOXA_U_5TUwDWw';
var map = window.map = new mapboxgl.Map({
    container: 'map',
    zoom: 15,
    center: [-74.0059, 40.7064],
    style: 'mapbox://styles/mapbox/streets-v11',
    hash: true
});
var date = new Date();
var time = date.getHours() * 60 * 60 + date.getMinutes() * 60 + date.getSeconds();
var timeInput = document.getElementById('time');
timeInput.value = time;
timeInput.oninput = () => {
    time = +timeInput.value;
    date.setHours(Math.floor(time / 60 / 60));
    date.setMinutes(Math.floor(time / 60) % 60);
    date.setSeconds(time % 60);
    map.triggerRepaint();
};
map.addControl(new mapboxgl.NavigationControl());
class BuildingShadows {
    constructor() {
        this.id = 'building-shadows';
        this.type = 'custom';
        this.renderingMode = '3d';
        this.opacity = 0.5;
    }
    onAdd(map, gl) {

        this.map = map;
        const vertexSource = `
        uniform mat4 u_matrix;
        uniform float u_height_factor;
        uniform float u_altitude;
        uniform float u_azimuth;
        attribute vec2 a_pos;
        attribute vec4 a_normal_ed;
        attribute lowp vec2 a_base;
        attribute lowp vec2 a_height;
        void main() {
            float base = max(0.0, a_base.x);
            float height = max(0.0, a_height.x);
            float t = mod(a_normal_ed.x, 2.0);
            vec4 pos = vec4(a_pos, t > 0.0 ? height : base, 1);
            float len = pos.z * u_height_factor / tan(u_altitude);
            pos.x += cos(u_azimuth) * len;
            pos.y += sin(u_azimuth) * len;
            pos.z = 0.0;
            gl_Position = u_matrix * pos;
        }
        `;
        const fragmentSource = `
        void main() {
            gl_FragColor = vec4(5.0, 0.0, 0.0, 0.1);

        }
        `;


        const vertexShader = gl.createShader(gl.VERTEX_SHADER);
        gl.shaderSource(vertexShader, vertexSource);
        gl.compileShader(vertexShader);
        const fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
        gl.shaderSource(fragmentShader, fragmentSource);
        gl.compileShader(fragmentShader);
        this.program = gl.createProgram();
        gl.attachShader(this.program, vertexShader);
        gl.attachShader(this.program, fragmentShader);
        gl.linkProgram(this.program);
        gl.validateProgram(this.program);
        this.uMatrix = gl.getUniformLocation(this.program, "u_matrix");
        this.uHeightFactor = gl.getUniformLocation(this.program, "u_height_factor");
        this.uAltitude = gl.getUniformLocation(this.program, "u_altitude");
        this.uAzimuth = gl.getUniformLocation(this.program, "u_azimuth");
        this.aPos = gl.getAttribLocation(this.program, "a_pos");
        this.aNormal = gl.getAttribLocation(this.program, "a_normal_ed");
        this.aBase = gl.getAttribLocation(this.program, "a_base");
        this.aHeight = gl.getAttribLocation(this.program, "a_height");
    }
    render(gl, matrix) {
        gl.useProgram(this.program);     
        const source = this.map.style.sourceCaches['composite'];
        const coords = source.getVisibleCoordinates().reverse();
        const buildingsLayer = map.getLayer('3d-buildings');
        const context = this.map.painter.context;
        const {lng, lat} = this.map.getCenter();
        const pos = SunCalc.getPosition(date, lat, lng);
        gl.uniform1f(this.uAltitude, pos.altitude);
        gl.uniform1f(this.uAzimuth, pos.azimuth + 3 * Math.PI / 2);
        map.setLight({
            anchor: 'map',
            position: [1.5, 180 + pos.azimuth * 180 / Math.PI, 90 - pos.altitude * 180 / Math.PI],
            'position-transition': {duration: 0},
            color: '#fdb'
            // color: `hsl(20, ${50 * Math.cos(pos.altitude)}%, ${ 200 * Math.sin(pos.altitude) }%)`
        }, {duration: 0});
        this.opacity = Math.sin(Math.max(pos.altitude, 0)) * 0.9;

        // ADDED: New Attempt to normalise the colour of the shadows
        gl.depthMask(false);
        gl.enable(gl.BLEND)
        gl.blendFuncSeparate(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA, gl.ONE, gl.ONE_MINUS_SRC_ALPHA);


        for (const coord of coords) {
            const tile = source.getTile(coord);
            const bucket = tile.getBucket(buildingsLayer);
            if (!bucket) continue;
            const [heightBuffer, baseBuffer] = bucket.programConfigurations.programConfigurations['3d-buildings']._buffers;
            gl.uniformMatrix4fv(this.uMatrix, false, coord.posMatrix);
            gl.uniform1f(this.uHeightFactor, Math.pow(2, coord.overscaledZ) / tile.tileSize / 8);

            for (const segment of bucket.segments.get()) {
                const numPrevAttrib = context.currentNumAttributes || 0;
                const numNextAttrib = 2;
                for (let i = numNextAttrib; i < numPrevAttrib; i++) gl.disableVertexAttribArray(i);
                const vertexOffset = segment.vertexOffset || 0;
                gl.enableVertexAttribArray(this.aPos);
                gl.enableVertexAttribArray(this.aNormal);
                gl.enableVertexAttribArray(this.aHeight);
                gl.enableVertexAttribArray(this.aBase);
                bucket.layoutVertexBuffer.bind();
                gl.vertexAttribPointer(this.aPos, 2, gl.SHORT, false, 12, 12 * vertexOffset);
                gl.vertexAttribPointer(this.aNormal, 4, gl.SHORT, false, 12, 4 + 12 * vertexOffset);
                heightBuffer.bind();
                gl.vertexAttribPointer(this.aHeight, 1, gl.FLOAT, false, 4, 4 * vertexOffset);
                baseBuffer.bind();
                gl.vertexAttribPointer(this.aBase, 1, gl.FLOAT, false, 4, 4 * vertexOffset);
                bucket.indexBuffer.bind();
                context.currentNumAttributes = numNextAttrib;     
                gl.drawElements(gl.TRIANGLES, segment.primitiveLength * 3, gl.UNSIGNED_SHORT, segment.primitiveOffset * 3 * 2);    
            }

        }
    }
}
map.on('load', () => {
    map.removeLayer('building');
    map.addLayer({
        'id': '3d-buildings',
        'source': 'composite',
        'source-layer': 'building',
        'type': 'fill-extrusion',
        'minzoom': 14,
        'paint': {
            'fill-extrusion-color': '#ddd',
            'fill-extrusion-height': ["number", ["get", "height"], 5],
            'fill-extrusion-base': ["number", ["get", "min_height"], 0],
            'fill-extrusion-opacity': 1
        }
    }, 'road-label');
    map.addLayer(new BuildingShadows(), '3d-buildings');
});
</script>
</body>
</html>

Answer 1

有各种变化，但

将所有阴影绘制到模具缓冲区中，然后在模具测试启用的情况下绘制一个四边形，使其仅在设置模具的位置绘制？
将所有阴影不透明地绘制到纹理中。在地图上绘制纹理为四边形。
将所有阴影绘制到深度缓冲区中。用深度测试集绘制一个四边形，以便仅在有阴影的地方绘制。

如何使用最新的Mapbox-gl-js版本避免透明度重叠？

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如何使用最新的Mapbox-gl-js版本避免透明度重叠？

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