# How do I setUniform for an array of a custom struct?
**URL:** https://discourse.processing.org/t/how-do-i-setuniform-for-an-array-of-a-custom-struct/33267
**Category:** Coding Questions
**Created:** [November 2, 2021, 4:57pm UTC](https://discourse.processing.org/t/how-do-i-setuniform-for-an-array-of-a-custom-struct/33267 "2021-11-02T16:57:28Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@modusponens](https://discourse.processing.org/u/modusponens)
#### Post date: [November 2, 2021, 4:57pm UTC](https://discourse.processing.org/t/how-do-i-setuniform-for-an-array-of-a-custom-struct/33267/1 "2021-11-02T16:57:28Z")
I have a shader with this struct defined in it:
```auto
struct LightInputData
{
vec3 worldPos;
vec3 color;
vec3 falloff;
};
```
and it has this uniform variable:
```auto
uniform LightInputData uPointLights[8];
```
How can I set this uniform in my sketch.js? I know that `setUniform` is the way to go when setting floats and vec3s and stuff, but I can’t seem to get this one to work. It is possible that I’m making some other mistake that’s preventing it from looking right, but I want to ask here before I bang my head on the wall much longer.
---
### Author:  [@micuat](https://discourse.processing.org/u/micuat)
#### Post date: [November 2, 2021, 5:35pm UTC](https://discourse.processing.org/t/how-do-i-setuniform-for-an-array-of-a-custom-struct/33267/2 "2021-11-02T17:35:04Z")
it seems like not straightforward to access uniform structs
>
so I doubt it’s supported in p5.js. In any case it might be helpful if you share an example code 🙂
---
### Author:  [@modusponens](https://discourse.processing.org/u/modusponens)
#### Post date: [November 2, 2021, 7:51pm UTC](https://discourse.processing.org/t/how-do-i-setuniform-for-an-array-of-a-custom-struct/33267/3 "2021-11-02T19:51:54Z")
EDIT: Uh oh, I may have spoken too soon. It works fine… in the trivial case with just one light in the array. I can’t get it to work with two lights yet. I’ll keep poking at it and I’ll update this again when I have a solution.
EDIT AGAIN: **Okay I fixed it** , it was a goof on my part elsewhere in my sketch, and I can confirm that my solution does indeed work with a dynamic number of point lights (up to my shader’s arbitrary maximum).
Thank you so much! That link contained just the answer I was looking for. For posterity, I have a uniform array of LightInputData in my fragment shader, like this:
```auto
struct LightInputData
{
vec3 worldPos;
vec3 color;
vec3 falloff;
};
uniform LightInputData uPointLights[MAX_POINT_LIGHT_COUNT];
```
and I want to use `setUniform` to send data from my sketch to this array. The correct way to do it is to access each named field in the struct individually, by name, within the array, like this:
```auto
phong.setUniform("uPointLights[0].worldPos", pointLight.WorldPosArray);
phong.setUniform("uPointLights[0].color", pointLight.ColorArray);
phong.setUniform("uPointLights[0].falloff", pointLight.FalloffArray);
```
…and so on for each element in the array. My solution for doing it with the array of lights I have in my sketch is to loop like this (and this does seem to work):
```auto
for (let i = 0; i < pointLightCount; ++i)
{
let pointLight = pointLights[i];
phong.setUniform(`uPointLights[${i}].worldPos`, pointLight.WorldPosArray);
phong.setUniform(`uPointLights[${i}].color`, pointLight.ColorArray);
phong.setUniform(`uPointLights[${i}].falloff`, pointLight.FalloffArray);
}
```