1432102 - WebGL shader compilation error on FF / Linux / NVidia Optimus in Intel mode

Status: RESOLVED DUPLICATE of bug 1399501

(Core :: Graphics: CanvasWebGL, defect)

Description

[charles.fleche]

Attachment: glxinfo.txt

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20180104101725

Steps to reproduce:

Try the example https://codepen.io/charlesfleche/pen/opJQRZ



Actual results:

On Firefox  / Linux / NVidia Optimus in Intel GPU mode, this examples fails during shader compilation:

```
0:2(12): warning: extension `GL_ARB_gpu_shader5' unsupported in fragment shader
0:10(29): error: sampler arrays indexed with non-constant expressions are forbidden in GLSL 1.30 and later
```

Firefox 57.0.4 (64 bits)
OS: Kubuntu 17.10
NVidia drivers: 384.111
GPU: GeForce GTX 960M



Expected results:

Blue colored shapes should appear. Accessing an array of `sampler2D` with a dynamic index breaks shader compilation.

```
uniform sampler2D textures[2];

void main(void) {
  // ...
  for (int i = 0 ; i < 2 ; ++i ) {
    gl_FragColor += texture2D(textures[i], vUv);
 }
  // ...
}
```

This is allowed in WebGL 1 (not in WebGL 2 anymore), and works on every OS / browser configuration I've tested (Linux / macOS / Windows / FF / Safari / Chrome) and it does work on FF / Linux / NVidia Optimus in discrete GPU (GTX 960M) mode: neither the warning nor the error appear and the example works fine.

Comment 1

[Sotaro Ikeda [:sotaro]]

:jgilbert, can you comment to the bug?