drawTexture_(texture, opacity) {
    const helper = this.helper;
    const gl = helper.getGL();

    helper.useProgram(this.textureProgram_);
    helper.bindTexture(texture, 0, U.TEXTURE);
    helper.bindAttribute(this.quadBuffer_, A.POSITION, 2);
    this.helper.setUniformFloatValue(U.OPACITY, opacity);

    gl.drawArrays(gl.TRIANGLES, 0, 6);
  }
@param {WebGLTexture} texture The texture to draw.
@param {number} opacity The opacity.