I'm sorry for digging out that old thread but this is the only thread I could find which mentioned an overlay blending mode in SFML. I use:
BlendMode(sf::BlendMode::DstColor, sf::BlendMode::SrcColor).
This works great, but the problem I'm having is that I have no way of controling the opacity of the effect, I've tried also:
BlendMode(sf::BlendMode::DstColor, sf::BlendMode::SrcColor, sf::BlendMode::Add, sf::BlendMode::SrcAlpha, sf::BlendMode::Zero, sf::BlendMode::Add);
But this seem not to work either. Is there any other way I could try to control the opacity in that mode?