text: /**
   * @filter           Brightness RGB
   * @description      Provides additive brightness for each channel of RGB
   * @param r -1 to 1 (-1 is solid black, 0 is no change, and 1 is solid red)
   * @param g -1 to 1 (-1 is solid black, 0 is no change, and 1 is solid green)
   * @param b -1 to 1 (-1 is solid black, 0 is no change, and 1 is solid blue)
   */
  function brightnessRGB(r, g, b) {
      gl.brightnessRGB = gl.brightnessRGB || new Shader(null, '\
          uniform sampler2D texture;\
          uniform float r;\
          uniform float g;\
          uniform float b;\
          varying vec2 texCoord;\
          void main() {\
              vec4 color = texture2D(texture, texCoord);\
              color.r += r;\
              color.g += g;\
              color.b += b;\
              gl_FragColor = color;\
          }\
      ');
  
      simpleShader.call(this, gl.brightnessRGB, {
          r: clamp(-1, r, 1),
          g: clamp(-1, g, 1),
          b: clamp(-1, b, 1),
      });
  
      return this;
  }
  