I'm new to Krita, and I've been trying to make pixel art. I'm running into a problem with trying to draw straight pixelated lines. I selected the Pixel_Art brush, and even used the shift button to ensure I'm drawing a straight line (not freehand), but no matter which 15 degree angle I draw, it's not "straight." This picture (https://imgur.com/a/xv1B7nh) will show you the exact problem I'm running into. I would think that the straight line tool would draw straight lines, even when using the pixel brush. I know it works, because I saw it done in a YT video (https://www.youtube.com/watch?v=s26tNYqDPlY&t=29s).

Thanks for your time and help.

Woody

The line tool does draw straight lines, but when you're using a pixel brush the pixel gets placed in the nearest image pixel, as calculated by the line fitting routine. This gives a line that is 'mathematically straight' in that the error from 'true straight' is minimised but the result is not 'neat and tidy'.
What you want is a line tool that draws a 'neat and tidy' line with a pixel brush. You can't have one.

Try this: get some graph paper with about five squares per inch and use a fine pencil to draw a straight line on it, about three inches long. Then use a black pen to fill in squares (pixels) along the pencil line as close to the pencil line as you can. You won't get a neat and tidy line.

You should be able to get a neat and tidy line at an angle of 45 degrees and I find it surprising that the line tool doesn't do that with the pixel brush. It may be rounding errors in the fitting routine but it still seems strange.

If you look at that YouTube video and make it full screen and slow it down and pause it now and then, the pixel brush is used for the vertical lines. For the sloping lines, a specially made stamp is used that stamps out a 'two along and one down' pixel line that has been designed to be an almost perfect match for an isometric grid at 26 degrees with 16px cell spacing. That is what is used for the sloping lines.
The video has been cropped so that you can't read the status bar to see what brush preset is being used but you can see use of the brush editor now and then.

I've just tried making a stamp that does that and it works nicely. Using an 18x9 image with a 'two along and one down' pixel line you can stamp a single cell width line for that particular isometric grid spacing.