How big can a Godot shader uniform array be?

Hard cap depends on platform/driver but commonly ~1024 vec4 elements for SPIR-V. Beyond that, use a sampler2D or sampler1D filled with data and sample by computed UV.

How do I pack data into a texture?

Create an Image with FORMAT_RGBAH or RGBAF, write floats per pixel, ImageTexture from it, pass as uniform sampler2D. Sample with texelFetch(tex, ivec2(i, 0), 0).

Performance vs uniform array?

Texture lookups are cached well; cost is negligible for occasional reads. For per-pixel reads of every element, a Storage Buffer (compute) is faster but adds complexity.

Fix: Godot Shader Uniform Array Exceeds Cap

Quick answer: Pack data into ImageTexture and sample with texelFetch. Bypasses uniform array cap.

You declare uniform vec4 data[2048]. Compile fails. Driver caps uniform arrays well below 2048 elements.

The Fix

# GDScript: pack values into a 1D texture
var n = 2048
var img = Image.create(n, 1, false, Image.FORMAT_RGBAH)
for i in n:
    img.set_pixel(i, 0, Color(values[i].x, values[i].y, values[i].z, 1.0))
var tex = ImageTexture.create_from_image(img)
material.set_shader_parameter("data_tex", tex)

// Shader
uniform sampler2D data_tex;

vec3 get_data(int i) {
    return texelFetch(data_tex, ivec2(i, 0), 0).rgb;
}

texelFetch reads the raw pixel without filtering. Index translates directly to texel position. Memory cost is the texture; sampling cost is one tap per read.

Verifying

Shader compiles. Visual matches uniform-array reference. No driver warnings. 2D arrays use 2D texture; index = (i % w, i / w).

“Texture for big arrays. Index is UV. Cap dodged.”

Related Issues

For shader instance uniform, see instance uniform. For shader TIME, see TIME.

Pack to texture. Sample. No cap.