Interface CustomLayerInterface

Interface for custom style layers. This is a specification for implementers to model: it is not an exported method or class.

Custom layers allow a user to render directly into the map's GL context using the map's camera. These layers can be added between any regular layers using Map#addLayer.

Custom layers must have a unique id and must have the type of "custom". They must implement render and may implement prerender, onAdd and onRemove. They can trigger rendering using Map#triggerRepaint and they should appropriately handle MapContextEvent with webglcontextlost and webglcontextrestored.

The renderingMode property controls whether the layer is treated as a "2d" or "3d" map layer. Use:

• "renderingMode": "3d" to use the depth buffer and share it with other layers
• "renderingMode": "2d" to add a layer with no depth. If you need to use the depth buffer for a "2d" layer you must use an offscreen framebuffer and CustomLayerInterface#prerender

Example

Custom layer implemented as ES6 class

class NullIslandLayer {
    constructor() {
        this.id = 'null-island';
        this.type = 'custom';
        this.renderingMode = '2d';
    }

    onAdd(map, gl) {
        const vertexSource = `
        uniform mat4 u_matrix;
        void main() {
            gl_Position = u_matrix * vec4(0.5, 0.5, 0.0, 1.0);
            gl_PointSize = 20.0;
        }`;

        const fragmentSource = `
        void main() {
            fragColor = vec4(1.0, 0.0, 0.0, 1.0);
        }`;

        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);
    }

    render(gl, matrix) {
        gl.useProgram(this.program);
        gl.uniformMatrix4fv(gl.getUniformLocation(this.program, "u_matrix"), false, matrix);
        gl.drawArrays(gl.POINTS, 0, 1);
    }
}

map.on('load', () => {
    map.addLayer(new NullIslandLayer());
});
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