How to correctly sample light index from the light index texture?

[Danielmelody]

Hi, great works!
I 'm a student and was doing my own implementation according to this repository and the paper below.

Which keeps confusing me is that when I sample from the light index texture, I get twinkle tiles

The width and height of light index texture are both Math.ceil(Math.sqrt(length of index)).
Here is how I sample this texture

        float listY = ((float(lightStartIndex + i) + 0.5) / uLightListLengthSqrt);
        float listX = mod((float(lightStartIndex + i) + 0.5), uLightListLengthSqrt) / uLightListLengthSqrt;
        listY = (listY / (uLightListLengthSqrt));

The uLightListLengthSqrt is the square root of light Indices length.
listX and listY will be used as the uv coordinate of the light-index texture.

Do you know what's wrong with my code?

[tiansijie]

hmm, hard to tell, but also be careful the light texture you pass to shader need to make sure that is correct as well.

[Danielmelody]

Well, it seems to be a bug of chrome(not sure). By adjusting a few code, it works. But I don't know how it works....
WebGL sucks sometimes compared to modern OpenGL

[tiansijie]

@Danielhu229 what kind of bug do you think? what did you do to fix this problem?

[Danielmelody]

@tiansijie Let me got some time to clear my code and do some test, later I will post here

[Danielmelody]

Anyway, thanks for your reply.

[Danielmelody]

Anyway, thanks for your reply.