Function createFBO

stackgl_modules/index.js:15316–15404

(gl, width, height, options)

}

function createFBO(gl, width, height, options) {

  //Update frame buffer error code values
  if(!FRAMEBUFFER_UNSUPPORTED) {
    FRAMEBUFFER_UNSUPPORTED = gl.FRAMEBUFFER_UNSUPPORTED
    FRAMEBUFFER_INCOMPLETE_ATTACHMENT = gl.FRAMEBUFFER_INCOMPLETE_ATTACHMENT
    FRAMEBUFFER_INCOMPLETE_DIMENSIONS = gl.FRAMEBUFFER_INCOMPLETE_DIMENSIONS
    FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT = gl.FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT
  }

  //Lazily initialize color attachment arrays
  var WEBGL_draw_buffers = gl.getExtension('WEBGL_draw_buffers')
  if(!colorAttachmentArrays && WEBGL_draw_buffers) {
    lazyInitColorAttachments(gl, WEBGL_draw_buffers)
  }

  //Special case: Can accept an array as argument
  if(Array.isArray(width)) {
    options = height
    height = width[1]|0
    width = width[0]|0
  }

  if(typeof width !== 'number') {
    throw new Error('gl-fbo: Missing shape parameter')
  }

  //Validate width/height properties
  var maxFBOSize = gl.getParameter(gl.MAX_RENDERBUFFER_SIZE)
  if(width < 0 || width > maxFBOSize || height < 0 || height > maxFBOSize) {
    throw new Error('gl-fbo: Parameters are too large for FBO')
  }

  //Handle each option type
  options = options || {}

  //Figure out number of color buffers to use
  var numColors = 1
  if('color' in options) {
    numColors = Math.max(options.color|0, 0)
    if(numColors < 0) {
      throw new Error('gl-fbo: Must specify a nonnegative number of colors')
    }
    if(numColors > 1) {
      //Check if multiple render targets supported
      if(!WEBGL_draw_buffers) {
        throw new Error('gl-fbo: Multiple draw buffer extension not supported')
      } else if(numColors > gl.getParameter(WEBGL_draw_buffers.MAX_COLOR_ATTACHMENTS_WEBGL)) {
        throw new Error('gl-fbo: Context does not support ' + numColors + ' draw buffers')
      }
    }
  }

  //Determine whether to use floating point textures
  var colorType = gl.UNSIGNED_BYTE
  var OES_texture_float = gl.getExtension('OES_texture_float')
  if(options.float && numColors > 0) {
    if(!OES_texture_float) {