function BatchShaderGenerator(vertexSrc, fragTemplate) {
        this.vertexSrc = vertexSrc;
        this.fragTemplate = fragTemplate;
        this.programCache = {};
        this.defaultGroupCache = {};
        if (fragTemplate.indexOf('%count%') < 0) {
            throw new Error('Fragment template must contain "%count%".');
        }
        if (fragTemplate.indexOf('%forloop%') < 0) {
            throw new Error('Fragment template must contain "%forloop%".');
        }
    }
@param vertexSrc - Vertex shader
@param fragTemplate - Fragment shader template