vec2 pixelUv(ivec2 pixelCoords, ivec2 dims)
{
vec2 uv;
uv.x = (float(pixelCoords.x * 2 - dims.x) / dims.x) * dims.x/dims.y; // account for aspect ratio
uv.y = (float(pixelCoords.y * 2 - dims.y) / dims.y);
return uv;
}