3d Pixel shader 2

shader_type canvas_item;

uniform int pixelSize: hint_range(2, 16, 2) = 4;

void fragment()
{
    vec2 iRes = 1.0 / SCREEN_PIXEL_SIZE;

    float onePixelSizeX = 1.0 / iRes.x;
    float onePixelSizeY = 1.0 / iRes.y;

    float cellSizeX =  float(pixelSize) * onePixelSizeX;
    float cellSizeY = float(pixelSize) * onePixelSizeY;

    float x = cellSizeX * floor(UV.x / cellSizeX);
    float y = cellSizeY * floor(UV.y / cellSizeY);

    COLOR = texture(SCREEN_TEXTURE, vec2(x, y));
}