random tiles loading on second screen as moving over

Hi peeps,
so im making a metrovania game and after i load in from my start screen to my first main game screen as i start moving to the second screen the first half on the second screen has random tiles loaded and a few bits of collision data. then as i move past and it goes off screen and go back to check it, its back to normal. game.jpg
 

puppydrum64

Active member
This is a bug with the scrolling that has plagued my games as well. I've done some research here but have yet to figure out the reason behind it completely. This is a quick summary of what I have found out so far:

When warping from a screen that doesn't scroll to one that does, the following values get written to these variables:tileError.png

Notice the last four values. If you were to open the PPU viewer in Mesen (with Ctrl+P), and hover your mouse over the glitch tiles, you'll see that their ID numbers equal these values. Why this happens, I have no idea. I tried making a breakpoint for whenever the game writes a value to the RAM while the accumulator equals #$80 (in hopes that I would locate the point where the value of #$80 is stored into updateTile_00) but I couldn't find it.

A less-than-ideal fix would be to simply rearrange the order of the tiles in the pixel editor in a way that hides the bug, but I can understand if you can't or don't want to do that.
 

9Panzer

Well-known member
I get this when I go from an 8x8 screen to a 16x16 screen. My work around was to create a "buffer screen" in-between thats completely black - seems to work for me :)
 

9Panzer

Well-known member
@puppydrum64 yes - so have the buffer screen be whatever you want the next screen to be. I place a warp tile and the warp to point on the same spot so literally all it does is warp you in and then warp you right out.
 

puppydrum64

Active member
@puppydrum64 yes - so have the buffer screen be whatever you want the next screen to be. I place a warp tile and the warp to point on the same spot so literally all it does is warp you in and then warp you right out.
Doesn't seem to work for me, I created a black screen and filled it with warp tiles and I still get glitchiness. The only difference is that the glitch tiles look different.

Edit: And somehow the bugginess also carries over to the title screen now. But only after dying once. When the game first starts up it looks normal.

tileBugYetAgain.png
 
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im loading from a 16x16 start screen to an 8x8 so ill try the blank screen buffer. i dont think i had this issue until i made my 16x16 start screen!
 
confirmed, a black transition screen fixed my issue. i used it to flash an image as the game started as my character fell through as a hidden sprite to the starting point of the game. thanks
 

puppydrum64

Active member
confirmed, a black transition screen fixed my issue. i used it to flash an image as the game started as my character fell through as a hidden sprite to the starting point of the game. thanks
Strangely enough it doesn't fix it for me, but that could be a result of the shooter module
 
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