method reset

Source

@override
void reset() {
  _viewportWidth = _canvasElement.width;
  _viewportHeight = _canvasElement.height;
  _activeRenderFrameBuffer = null;
  _renderingContext.bindFramebuffer(gl.FRAMEBUFFER, null);
  _renderingContext.viewport(0, 0, _viewportWidth, _viewportHeight);
  _projectionMatrix.setIdentity();
  _projectionMatrix.scale(2.0 / _viewportWidth, - 2.0 / _viewportHeight, 1.0);
  _projectionMatrix.translate(-1.0, 1.0, 0.0);
  _activeRenderProgram.projectionMatrix = _projectionMatrix;
}