TextureSampleScreenSpace.osl

/*
Screen space texture sampling for Redshift.
Handles colorspace correctly in Redshift.
This file is licensed under Apache 2.0 license
*/

shader ScreenSpaceTex
[[  string help = "Screen Space Texture Projection Mapping",
    string label = "Screen Space Texture Map" ]]
(
    string file = "" [[string widget = "filename", int connectable = 0]],
    string fileColorSpace = "" [[string label = "ColorSpace", string widget = "colorspace"]],
    point scale = point(1.0, 1.0, 1.0),
    output color outColor = 0
)
{
    point screenCordinates = transform("world", "screen", P);
    //this is a weird way to do this so I have to rescale the coordinates.
    screenCordinates += -1;
    screenCordinates *= 0.5;

    //texture tiling
    screenCordinates *= scale;
    color textureSample = texture(file, screenCordinates.x, 1-screenCordinates.y);
    //reverse baked in colorspace
    color textureSampleRAW = transformc("ACEScg", "scene-linear Rec.709-sRGB", textureSample);
    outColor = transformc(fileColorSpace, "ACEScg", textureSampleRAW);
}