// This does once-per-light work, as well as once-per-material-per-light work.
// So this ends up being called multiple times with the same parameters, except
// for matObjName.
// matObjName is the name of the material being exported
// lightObjectName is the name of the light
public void ExportLight(LightPayload payload, IExportableMaterial exportableMaterial)
{
ObjectName lightNodeName = new ObjectName(payload.legacyUniqueName); // does need to be unique
// Add the light to the scene -- this does _not_ need to be done per-material.
// As a result, the node will generally have already been created.
GlTF_Node node = GlTF_Node.GetOrCreate(G, lightNodeName, payload.xform, null, out _);
node.lightNameThatDoesNothing = payload.name;
// The names of the uniforms can be anything, really. Named after the light is the most
// logical choice, but note that nobody checks that two lights don't have the same name.
// Thankfully for Tilt Brush, they don't.
// This should probably have used a guaranteed-unique name from the start but I don't want
// to change it now because it'd break my diffs and be kind of ugly.
string lightUniformPrefix = payload.name;
AddUniform(exportableMaterial, lightUniformPrefix + "_matrix",
GlTF_Technique.Type.FLOAT_MAT4, GlTF_Technique.Semantic.MODELVIEW, node);
// Add light color.
GlTF_Material mtl = G.materials[exportableMaterial];
var val = new GlTF_Material.ColorKV {
key = lightUniformPrefix + "_color",
color = payload.lightColor
};
mtl.values.Add(val);
AddUniform(exportableMaterial, val.key,
GlTF_Technique.Type.FLOAT_VEC4, GlTF_Technique.Semantic.UNKNOWN, node);
}
/// Convert the light colors to linear
/// Beware that you will lose information when quantizing down from
/// linear-float32 to linear-uint8.
public static void ConvertToLinearColorspace(LightPayload lights)
{
// XXX: these values can be > 1 because they are pre-multiplied by intensity
// Is it more appropriate to convert the base color from sRGB -> Linear,
// _then_ multiply by intensity?
lights.ambientColor = lights.ambientColor.linear;
for (int i = 0; i < lights.Count; i++)
{
lights.lightColor[i] = lights.lightColor[i].linear;
}
}