Can I load 2D IES profile?

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1

I tried to load IES profile to light source. As I looked into a source file and find following comment in IESLightProfilesCommon.usf.

// Apply 1D IES light profile texture
float ComputeLightProfileMultiplier(float3 WorldPosition, float3 LightPosition, float3 LightDirection)

and further dig into source code, it looks to me actually maps to 1D texture of 0 to 255 for x axis.

What can I do to apply 2D IES profile? Can I customize light source to apply my own IES profile routine?

2

I tried to modify source code. I looked into IESLoader.cpp to accommodate 256x256 profile. I put polar conversion in IESLightProfilesCommon.usf of ComputeLightProfileMultiplier and changed toTexture2DSampleLevel from Texture1DSampleLevel. Then successfully render image with 2D IES. It looks OK.
So my question is, is there a reason to limit IES only 1D ? while 2D profile looks doable without much of trouble. I look forward to 2D support in future, since car head lump most likely using LM-63-1995 2D IES profiles.

3

Hi, otsl-0110. Can you further explain this please? Does it in other words address the issue that Unreal takes a vertical slice through the lighting profile and then copies that for 360 degrees around the vertical axis?

4

Could you possibly share you code if you don’t mind?