I've read questions that have come up about duplicating 2 screens by using a trick with the slide effect.
However that solution works for 2 screens. I've tried a layer router method which seemed really complicated, ugly, and limiting and consumes view able deck space for clips. I can only see 7 layers high with my monitor so avoiding entire layers dedicated to layer routers is best.
I've tried the tile effect which just about works and great because the effect works on a layer level so you have full control on which layers you want to tile not ALL or ONE and at the price of using layer real estate.
The draw back to using the tile effect is when you tile your video 3 times it requires being scaled 300%. The tile effects texture size seems to be locked the the footage resolution. So the details of your 1080p video is now lost when it's tiled even though the footage duplicated 3x should be 5760 x 1080.
Layer routers help maintain the resolution but have draw backs like options such as only focus on ALL or ONE layer at a time. Then it required 2 slide effects on that layer router with very careful positioning with the blend modes set to add to achieve anything close to 3 tiles screens. Also the center imaged would be every so slightly brighter with isn't great.
The other downside is lets say you wanted a layer that spans across all screens (Not duplicated) then want 2 or more layers above that with 1080p content that you want to duplicate 3 times. A layer router can't select individual layers to route beyond 1.
The reason I'm looking for a solution is so existing 1080p content can be duplicated across 3 screens. But also have layers like masks that are not duplicated but instead span across all 3 screens as one large image. I've tried for day's to find the best solution in Resolume and I'm pretty disappointed with the results.
