gl-vertex-attrib-normalized-int.html

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    <title>WebGL 2 Normalized Vertex Attributes Conformance Test</title>

    <meta charset="utf-8">

    <link rel="stylesheet" href="../../resources/js-test-style.css"/>

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    <canvas width=1 height=1></canvas>

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    <script id="vertex-shader" type="x-shader/x-vertex">#version 300 es

        layout(location = 0) in vec3 vertex;

        out float normAttrib;

        void main(void) {

            gl_Position = vec4(vertex.xy, 0, 1);

            normAttrib = vertex.z;

    </script>

    <script id="fragment-shader" type="x-shader/x-fragment">#version 300 es

        in lowp float normAttrib;

        layout(location=0) out lowp vec4 fragColor;

        void main(void) {

            fragColor = vec4(vec3(normAttrib == -1.0 ? 1.0 : 0.0), 1);

    </script>

    <script src="../../js/js-test-pre.js"></script>

    <script src="../../js/webgl-test-utils.js"></script>

    <script>

        (function () {

            'use strict';

            var wtu = WebGLTestUtils;

            var gl = wtu.create3DContext(document.querySelector('canvas'), null, 2);

            var program = wtu.setupProgram(gl, ['vertex-shader', 'fragment-shader']);

            gl.useProgram(program);

            var buffer = gl.createBuffer();

            gl.bindBuffer(gl.ARRAY_BUFFER, buffer);

            gl.bufferData(gl.ARRAY_BUFFER, new Int8Array([

                // Here we set the third component (the one that's actually tested)

                // to (MIN_INT + 1). If non-zero-preserving rules are used, it'll be

                // converted to a float that's slightly greater than -1. If zero-preserving

                // rules are used, as the GLES 3 spec requires, result of conversion

                // should be exactly -1.

                -0x80,  0x7f, -0x7f,

                 0x7f,  0x7f, -0x7f,

                -0x80, -0x7f, -0x7f,

                -0x80, -0x7f, -0x7f,

                 0x7f,  0x7f, -0x7f,

                 0x7f, -0x80, -0x7f

            ]), gl.STATIC_DRAW);

            gl.enableVertexAttribArray(0);

            gl.vertexAttribPointer(0, 3, gl.BYTE, true, 0, 0);

            gl.drawArrays(gl.TRIANGLE_STRIP, 0, 6);

            wtu.checkCanvas(gl, [255, 255, 255, 255], "should be opaque white");

        }());

    </script>

    <script>

        description('Verify that conversion of normalized signed int attributes to floats uses zero-preserving rule.');

        window.successfullyParsed = true;

    </script>

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