framebuffer-without-color-attachment.html

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This WPT test may be referenced by the following Test IDs:
- /webgl/framebuffer-without-color-attachment.html - WPT Dashboard Interop Dashboard

<!doctype html>

<meta charset="utf-8">

<title>A complete framebuffer without a color attachment can be drawn to but not read from</title>

<link rel="author" title="mxmgorin" href="mailto:102797145+mxmgorin@users.noreply.github.com">

<link rel="help" href="https://registry.khronos.org/webgl/specs/latest/1.0/#READING_FROM_MISSING_ATTACHMENT">

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script>

function depthOnlyContext(version) {

    const gl = document.createElement("canvas").getContext(version);

    const renderbuffer = gl.createRenderbuffer();

    gl.bindRenderbuffer(gl.RENDERBUFFER, renderbuffer);

    gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, 4, 4);

    gl.bindFramebuffer(gl.FRAMEBUFFER, gl.createFramebuffer());

    gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, renderbuffer);

    assert_equals(gl.checkFramebufferStatus(gl.FRAMEBUFFER), gl.FRAMEBUFFER_COMPLETE);

    return gl;

function pointProgram(gl) {

    const shader = (type, source) => {

        const shader = gl.createShader(type);

        gl.shaderSource(shader, source);

        gl.compileShader(shader);

        return shader;

};

    const program = gl.createProgram();

    gl.attachShader(program, shader(gl.VERTEX_SHADER,

        "void main() { gl_Position = vec4(0.0, 0.0, 0.0, 1.0); gl_PointSize = 1.0; }"));

    gl.attachShader(program, shader(gl.FRAGMENT_SHADER,

        "void main() { gl_FragColor = vec4(1.0); }"));

    gl.linkProgram(program);

    return program;

for (const version of ["webgl", "webgl2"]) {

    test(function() {

        const gl = depthOnlyContext(version);

        gl.clear(gl.DEPTH_BUFFER_BIT);

        assert_equals(gl.getError(), gl.NO_ERROR);

    }, `${version}: clear`);

    test(function() {

        const gl = depthOnlyContext(version);

        gl.useProgram(pointProgram(gl));

        gl.drawArrays(gl.POINTS, 0, 1);

        assert_equals(gl.getError(), gl.NO_ERROR);

    }, `${version}: drawArrays`);

    test(function() {

        const gl = depthOnlyContext(version);

        gl.readPixels(0, 0, 1, 1, gl.RGBA, gl.UNSIGNED_BYTE, new Uint8Array(4));

        assert_equals(gl.getError(), gl.INVALID_OPERATION);

    }, `${version}: readPixels`);

</script>