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getUniformFloat(String name) fails on Vulkan #180595
Description
Steps to reproduce
- Write code using getUniformFloat
- Build for vulkan
- Boom
Expected results
Not boom
Actual results
Uniform with the given name not found.
Code sample
Code sample
shader.getUniformFloat("uTime").set(1.0);// shaders/my_gradient.frag
#version 460 core
#include <flutter/runtime_effect.glsl>
uniform vec2 uSize; // The size of the area being drawn
uniform float uTime;
out vec4 fragColor;
uniform vec3 uColor;
void main() {
// FlutterFragCoord() gives the pixel coordinate.
// Divide by uSize to get normalized coordinates (uv) between 0.0 and 1.0.
vec2 uv = FlutterFragCoord().xy / uSize;
// Define two colors for the gradient.
vec4 color1 = vec4(1.0, 0.0, 0.0, 1.0); // Dark Blue
vec4 color2 = vec4(uColor, 1.0); // Orange/Red
fragColor = mix(color1, color2, sin(-uTime));
}Screenshots or Video
Screenshots / Video demonstration
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Logs
Logs
[Paste your logs here]Flutter Doctor output
No
Activity
walley892 commentedon Jan 6, 2026
For Vulkan, it looks like we convert all shader uniforms into a single struct with the name
_RESERVED_IDENTIFIER_FIXUP_gl_DefaultUniformBlock.We don't have the information on the dart side to make this work correctly. The Uniform information that gets passed to dart is generated here, and defined here and here
gaaclarke commentedon Jan 6, 2026
Fixing this should also move or eliminate the shortcut in
flutter/engine/src/flutter/testing/dart/fragment_shader_test.dart
Line 46 in 1e87bd8
(The tests already run against vulkan)
walley892 commentedon Feb 12, 2026
Fixed by #181286
github-actions commentedon Mar 1, 2026
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flutter doctor -vand a minimal reproduction of the issue.