Function getWebGLContext

script.js:118–168

(canvas)

startGUI();

function getWebGLContext (canvas) {
    const params = { alpha: true, depth: false, stencil: false, antialias: false, preserveDrawingBuffer: false };

    let gl = canvas.getContext('webgl2', params);
    const isWebGL2 = !!gl;
    if (!isWebGL2)
        gl = canvas.getContext('webgl', params) || canvas.getContext('experimental-webgl', params);

    let halfFloat;
    let supportLinearFiltering;
    if (isWebGL2) {
        gl.getExtension('EXT_color_buffer_float');
        supportLinearFiltering = gl.getExtension('OES_texture_float_linear');
    } else {
        halfFloat = gl.getExtension('OES_texture_half_float');
        supportLinearFiltering = gl.getExtension('OES_texture_half_float_linear');
    }

    gl.clearColor(0.0, 0.0, 0.0, 1.0);

    const halfFloatTexType = isWebGL2 ? gl.HALF_FLOAT : halfFloat.HALF_FLOAT_OES;
    let formatRGBA;
    let formatRG;
    let formatR;

    if (isWebGL2)
    {
        formatRGBA = getSupportedFormat(gl, gl.RGBA16F, gl.RGBA, halfFloatTexType);
        formatRG = getSupportedFormat(gl, gl.RG16F, gl.RG, halfFloatTexType);
        formatR = getSupportedFormat(gl, gl.R16F, gl.RED, halfFloatTexType);
    }
    else
    {
        formatRGBA = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
        formatRG = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
        formatR = getSupportedFormat(gl, gl.RGBA, gl.RGBA, halfFloatTexType);
    }

    ga('send', 'event', isWebGL2 ? 'webgl2' : 'webgl', formatRGBA == null ? 'not supported' : 'supported');

    return {
        gl,
        ext: {
            formatRGBA,
            formatRG,
            formatR,
            halfFloatTexType,
            supportLinearFiltering
        }
    };
}

function getSupportedFormat (gl, internalFormat, format, type)
{