See QRhiGraphicsPipeline::TargetBlend::TargetBlend{QRhiGraphicsPipeline::ColorMask,bool,QRhiGraphicsPipeline::BlendFactor,QRhiGraphicsPipeline::BlendFactor,QRhiGraphicsPipeline::BlendOp,QRhiGraphicsPipeline::BlendFactor,QRhiGraphicsPipeline::BlendFactor,QRhiGraphicsPipeline::BlendOp}