Erasing from a RenderTexture with BlendMode Factors

[HughPH]

Hi, I'm having a little difficulty understanding the factors and parameters of BlendMode.

The effect I want to achieve is simply to have the destination pixels replaced with rgba(0,0,0,0) - actually it doesn't matter what the R, G, B components are, but let's just say 0 for now.

Am I meant to be putting the SrcColor factor into the SourceFactor, DstColor into the DestinationFactor? Or should I be putting DstColor into both and using Equation.Subtract?

Evidently I'm confused...

(Use case is painting - not drawing sprites or shapes - directly onto parallax layers that slide over one another. So drawing in the background colour that's behind the RenderTexture just isn't an option.)

Many thanks!

[Laurent]

If you want to replace pixels, then just disable alpha-blending (sf::BlendNone).

[HughPH]

Thankyou Laurent - and thankyou for creating this awesome library

DstAlpha - DstAlpha also works, but I guess that could be slower so I'll try BlendMode.None