Viewport

totebo

Is Viewport a good alternative to RenderTarget CPU wise? My use case is showing items outside of the screen area at the edge of the screen, like waypoint arrows but with the actual gfx scaled down to fit inside an arrow.

hgy29

If you would have refreshed your RenderTarget each frame, then yes Viewport will be more efficient, not CPU wise but GPU wise. You save the need for draw your render target on screen.

totebo

That's a bit of magic right there. So on a mobile phone it's likely to be a small hit in performance?

SinisterSoft

No, it's likely to be faster.

The reason is that with render target you have to first render to the texture, then render the texture onto the screen. With the viewport you point to your list of sprites then put the viewport on the screen.

A disadvantage is that viewports cannot be rotated (as far as I know, I might be wrong), but a render target can be as it's a regular sprite.

hgy29

@SinsiterSoft, Viewports can be rotated, scaled, translated, you can apply any transform matrix you like.

totebo

Guys, Viewport appears to be a hidden gem! Can't wait to start playing with it.

SinisterSoft

@hgy29, so I can have a viewport that is a square, but tilted by 45 degrees and the clipping will work ok so that it looks like a diamond shape on the screen?

hgy29

@SinisterSoft, no you can't because clipping only works with screen axis aligned rectangular regions. This is not a viewport limitation however, but rather a clipping one.

SinisterSoft

I'd have to render it to a rendertarget then show that sprite on the screen then.