Texture:isReadable
Gets whether the Texture can be drawn and sent to a Shader.

Canvases created with stencil and/or depth PixelFormats are not readable by default, unless readable=true is specified in the settings table passed into love.graphics.newCanvas.

Non-readable Canvases can still be rendered to.
readable = Texture:isReadable()
readable boolean Whether the Texture is readable.