attributeSetFloats_(attrName, vsize, arr) {
    const gl = this.gl_;
    gl.bindBuffer(gl.ARRAY_BUFFER, gl.createBuffer());
    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(arr), gl.STATIC_DRAW);
    const attr = gl.getAttribLocation(this.program_, attrName);
    gl.enableVertexAttribArray(attr);
    gl.vertexAttribPointer(attr, vsize, gl.FLOAT, false, 0, 0);
  }
Sets a floating point shader attribute to the values in arr.
@param {string} attrName the name of the shader attribute to set
@param {number} vsize the number of components of the shader attribute's
  type
@param {!Array<number>} arr the values to set
@private