textures loaded vertically flipped
OpenGl assumes (https://registry.khronos.org/OpenGL-Refpages/gl4/html/glTexImage2D.xhtml) that:
"The first element corresponds to the lower left corner of the texture image. Subsequent elements progress left-to-right through the remaining texels in the lowest row of the texture image, and then in successively higher rows of the texture image. The final element corresponds to the upper right corner of the texture image."
But we give rasterio images to OpenGl, that assume that the first element is the upper left corner. Thus textures are vertically flipped.
(Additionnaly OpenGl assumes that the image is in shape=(rows, columns, bands) whereas rasterio provides images in shape=(bands, rows, columns) but it is already correctly handled in the code)