Rotated TiledImagePaint causes misplaced pixels and IndexDefect.

[nico-robert]

Rotated a TiledImagePaint causes an IndexDefect in debug mode. In release mode, some pixels appear in the wrong places.

import std/math
import pixie

let tile = newImage(4, 4)
tile.fill(rgba(255, 255, 255, 255))

for x in 0 ..< tile.width:
  tile[x, 0] = rgba(35, 115, 210, 255)

let paint = newPaint(TiledImagePaint)
paint.image = tile
paint.imageMat = rotate(-7.0.float32 * PI.float32 / 180.0.float32)

let image = newImage(256, 160)
image.fill(paint)
image.writeFile("result.png")

On the Nim forum, janAkali suggested the following workaround in images.nim file, which fixes the issue in my tests:

x0y0 = image.unsafe[x0.euclMod(image.width), y0.euclMod(image.height)]
x1y0 = image.unsafe[x1.euclMod(image.width), y0.euclMod(image.height)]
x0y1 = image.unsafe[x0.euclMod(image.width), y1.euclMod(image.height)]
x1y1 = image.unsafe[x1.euclMod(image.width), y1.euclMod(image.height)]

However, I would prefer not not to have to modify Pixie’s source code locally, which is why I am reporting the issue here.