placeholder fields in struct LightData

[alexgu754]

in the material workflow, the struct:
struct LightData {
// The color (.rgb) and pre-exposed intensity (.w) of the light.
// The color is an RGB value in the linear sRGB color space.
// The pre-exposed intensity is the intensity of the light multiplied by
// the camera's exposure value.
vec4 colorIntensity;
...
};
is predefined. there is (no?) way to add an extra variable that corresponds to different behavior for this particular light.

currently the hack solution we use is to just hijack the world position field and interpret different decimals to mean different things. ie. position of x = .0111
is interpreted as the light using the r channel of a shadowmap texture

would be great if there was something like
struct LightData {
vec4 placeholder1, placeholder2, placeholder3;
};