Function detectGLCapabilities

tfjs-react-native/src/camera/camera.ts:54–97

(gl: WebGL2RenderingContext)

 * @doc {heading: 'Media', subheading: 'Camera'}
 */
export async function detectGLCapabilities(gl: WebGL2RenderingContext) {
  if (glCapabilities.glCapabilitiesTested.get(gl)) {
    return;
  }
  // Test whether we can successfully download from an RGB texture.
  // Notably this isn't supported on iOS, but we use this test rather than a
  // platform check to be more robust on android devices we may not have
  // directly tested.

  // Set this to true temporarily so that fromTexture does not
  // use its workaround.
  glCapabilities.canDownloadFromRGBTexture.set(gl, true);

  try {
    const height = 2;
    const width = 4;  // This must be a multiple of 4.
    const data = new Uint8Array(height * width * 4);
    for (let i = 0; i < data.length; i++) {
      data[i] = i;
    }
    const sourceDims = {height, width, depth: 4};
    const tex = uploadTextureData(data, gl, sourceDims);

    const targetDims = {height, width, depth: 3};
    const downloaded = fromTexture(gl, tex, sourceDims, targetDims);
    const downloadedData = await downloaded.data();
    tf.dispose(downloaded);

    const matches = tf.util.arraysEqual(downloadedData, [
      0,  1,  2,  4,  5,  6,  8,  9,  10, 12, 13, 14,
      16, 17, 18, 20, 21, 22, 24, 25, 26, 28, 29, 30
    ]);

    if (matches) {
      glCapabilities.canDownloadFromRGBTexture.set(gl, true);
    } else {
      glCapabilities.canDownloadFromRGBTexture.set(gl, false);
    }
  } catch (e) {
    glCapabilities.canDownloadFromRGBTexture.set(gl, false);
  } finally {
    glCapabilities.glCapabilitiesTested.set(gl, true);
  }
}

/**
 * Transfers tensor data to an RGB(A) texture.