I can reproduce this and have several times by accident.
If you setup a simple a terrain 3 materials no normal maps needed. Follow all the basic setups to get a terrain to work properly, paint each color over the entire thing while the shaders compile, etc etc.
Use the re-sample, expand, clip options under the Terrain / Manage / Change Component Size increase the complexity of the terrain, then do it again step by step using the default options this should break it, if not then start to decrease it.
At some point the terrain being changed using this method will break your ability to paint the terrain or see the painting happening live as you are painting it.
You can sit there trying all sort things and you will be painting the terrain but you will not be able to see these changes.
Some times its lets you paint a small part of the terrain but you will hit a border and it will not change.
If you keep trying to paint it like I stated you are painting it but you have no visual representation of your changes it is if the border of the component is a hard line visually in reality again you are painting over this border.
Two ways to solve this:
Save everything, close the editor, reload the level, and you will see what ever you painted last actually show up, and you will be able to paint again and see it as it is happening.
Go to the terrain texture, and disconnect or break a connection, apply it, save it, after the shaders finish recompiling, reconnect the broken connection, and save / apply it again wait for the shaders to recompile and you should be able to see all your changes, and make new changes and see them happen as you make them.
Thanks for taking the time to submit this report. Unfortunately, I have not been able to reproduce your issue and am going to need some more simplified steps as well as some screenshots in order to more easily understand the issue you are experiencing and visualize the process.
There are multiple ways to create a landscape material, and each with their own specific nuances that can alter the outcome. Is the issue simply, resampling the terrain causes it to be unusable at a certain point? If this is the case could you also clarify this process. Have you made sure that you use the ‘Build All’ button after re-sampling and altering the landscape.
Yes I tried the build button, the only 2 methods of recovery listed are the only two I have found.
Happens to me all the time maybe 6 - 10 times in the last 2 months.
You will know you have the terrain in this broken state if you are painting on it and not see it update as you are painting. If you reload the editor it fixes it and if you go to the terrain material and disconnect it you will also see the previous paint strokes, and are able to paint on it once it.
I will try to get you a screen shot of how I break it.
Well I found the easiest way to reproduce the bug for you, have your terrain use 2x2 sections paint on it for a bit sculpt it a bit, then change it to 1x1 with resample on, this terrain was 256x256 with max res.
This image shows that the 3 layer terrain surface is corrupted by blending all 3 of the materials together at 100%.
You cant visually see that I cant paint but I could not paint.
Meaning if i was painting it would not update live if I saved and closed the editor then I would see what I had painted during this broken state.
I could stream this for you on Twitch if you want took me less then a minute to break it. Let me know.
Thanks for the clear and precise repro steps. I was able to confirm what you are reporting and have gone ahead and entered a bug report for the issue. You can track the issue following the link below on our new Public Issues Tracker.
Once the issue has been addressed by our engineers, the fix will be added to the release notes for fixed issues within an upcoming full engine or hotfix release.
Let me know if you have further questions or need additional assistance.
