ent shader
            v_texCoord = vec2(a_texCoord.x, 1.0 - a_texCoord.y);
        }`;

    const FRAG_SOURCE_DEFAULT = `#version 300 es
        precision highp float;

        uniform sampler2D u_image;
        uniform vec2 u_dimensions;

        in vec2 v_texCoord;
        out vec4 out_color;

        void main()
        {
            out_color = texture(u_image, v_texCoord);
        }`;

    const FRAG_SOURCE_GREY = `#version 300 es
        precision highp float;

        uniform sampler2D u_image;
    