Function webglLinkProgram

src/WebGL/webglLinkProgram.js:13–156

* Defines UI for links in webgl renderer.

()

 * Defines UI for links in webgl renderer.
 */
function webglLinkProgram() {
    var ATTRIBUTES_PER_PRIMITIVE = 6, // primitive is Line with two points. Each has x,y and color = 3 * 2 attributes.
        BYTES_PER_LINK = 2 * (2 * Float32Array.BYTES_PER_ELEMENT + Uint32Array.BYTES_PER_ELEMENT), // two nodes * (x, y + color)
        linksFS = [
            'precision mediump float;',
            'varying vec4 color;',
            'void main(void) {',
            '   gl_FragColor = color;',
            '}'
        ].join('\n'),

        linksVS = [
            'attribute vec2 a_vertexPos;',
            'attribute vec4 a_color;',

            'uniform vec2 u_screenSize;',
            'uniform mat4 u_transform;',

            'varying vec4 color;',

            'void main(void) {',
            '   gl_Position = u_transform * vec4(a_vertexPos/u_screenSize, 0.0, 1.0);',
            '   color = a_color.abgr;',
            '}'
        ].join('\n'),

        program,
        gl,
        buffer,
        utils,
        locations,
        linksCount = 0,
        frontLinkId, // used to track z-index of links.
        storage = new ArrayBuffer(16 * BYTES_PER_LINK),
        positions = new Float32Array(storage),
        colors = new Uint32Array(storage),
        width,
        height,
        transform,
        sizeDirty,

        ensureEnoughStorage = function () {
            // TODO: this is a duplicate of webglNodeProgram code. Extract it to webgl.js
            if ((linksCount+1)*BYTES_PER_LINK > storage.byteLength) {
                // Every time we run out of space create new array twice bigger.
                // TODO: it seems buffer size is limited. Consider using multiple arrays for huge graphs
                var extendedStorage = new ArrayBuffer(storage.byteLength * 2),
                    extendedPositions = new Float32Array(extendedStorage),
                    extendedColors = new Uint32Array(extendedStorage);

                extendedColors.set(colors); // should be enough to copy just one view.
                positions = extendedPositions;
                colors = extendedColors;
                storage = extendedStorage;
            }
        };

    return {